Group Title: theory and application of a continuous source in atomic absorption flame spectrometry
Title: The Theory and application of a continuous source in atomic absorption flame spectrometry
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 Material Information
Title: The Theory and application of a continuous source in atomic absorption flame spectrometry
Alternate Title: Atomic absorption flame spectrometry
Physical Description: vi, 82 leaves. : illus. ; 28 cm.
Language: English
Creator: McGee, William Walter, 1939-
Publication Date: 1966
Copyright Date: 1966
 Subjects
Subject: Spectrometer   ( lcsh )
Absorption spectra   ( lcsh )
Chemistry thesis Ph. D
Dissertations, Academic -- Chemistry -- UF
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Thesis: Thesis--University of Florida, 1966.
Bibliography: Bibliography: leaves 79-81.
Additional Physical Form: Also available on World Wide Web
General Note: Manuscript copy.
General Note: Vita.
 Record Information
Bibliographic ID: UF00097867
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000558943
oclc - 13428197
notis - ACY4385

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THE THEORY AND APPLICATION OF

A CONTINUOUS SOURCE IN ATOMIC

ABSORPTION FLAME SPECTROMETRY








By

WILLIAM WALTER McGEE III


A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FU L FILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY











UNIVERSITY OF FLORIDA
December, 1966












ACKNOWLEDGMENTS


I wish to thank the members of my committee;

Dr. L. A. Arnold, Dr. A. P. Black, Dr. W. S. Brey, and

Dr. R. C. Stoufer, for their help and advice.

I want to especially thank my research director and

committee chairman, Dr. J. D. Winefordner for the help and

encouragement he has given me not only in the writing of

this dissertation, but throughout my entire stay at the

University of Florida.

Also, a very grateful thank you goes to Dr. L.

de Galan. Dr. de Galan was the sounding board for many of

my ideas. His many suggestions were of invaluable assist-

ance to me.

And finally, my deepest thanks go to my wife, Mary

Ann, to whom I dedicate this dissertation. Without her

help this study would not have been possible.












TABLE OF CONTENTS

Page
ACINOWLEDGMENTS ... . . . . . . . . ii

LIST OF TABLES. . . . . . . . . . v

LIST OF FIGURES . . . . . . . . . vi

INTRODUCTION. . . . . . . . .. 1

EXPERIMENTAL MEASUREMENTS DESIGNED TO ESTABLISH THE
RELATIONSHIP BETWEEN THE MEASURED SIGNAL AND THE
ATOMIC CONCENTRATION WHEN USING A CONTINUOUS
SOURCE OF RADIATION. . . . .. . . .. 5

Introduction . . . . . . . . .. 5

Theory . . . . . . . . . 6

Atomic absorption measurement with a line
source . . . . . . . 7
Atomic absorption measurement with a
continuous source. . . . . . . 10
A discussion of the curves of growth, total
absorption (AT), and the damping constant
and present means of calculation . . . 14

Experimental Conditions. . . . . . 22

Description of the experimental conditions. . 24

Experimental Results . . . . . . .. 36

Discussion . . . . . . . . . 47

Discussion of errors. . . . . . . 47
Comparison of results with literature data. . 49

EXPERIMENTAL MEASUREMENTS DESIGNED TO EXTEND
ANALYTICAL APPLICATIONS OF THE CONTINUOUS SOURCE 54

Introduction . . ... . . . . 54


iii












Experimental .

Appara;us .
Solutions .
Procedure .

Results. .

Discussion . .

FUTURE WORK. . .

CONCLUSIONS. . .

APPENDIX I . . .

LITERATURE CITED .

BIOGRAPHICAL SKETCH.


a. . e * e e e * e e e


* .

* -
. .


* * 0 ;


* *


* C C C C



C C C *
. . .

. . .

. . .

. . .

. . .


S .* C C C C


* *
. .
. .


Page


55

55
63
5

64

66


74

76


73

79

82


S a .



* d 0 C
* C C * .

. . . .

. . ...


. . . .













LIST OF TABLES


Table Page

1. Specific Components Used in Experimental
System for Measurement of the a Parameter. . 27

2. Values of Parameters Dependent Upon Flame Type 29

3. Values of Parameters Dependent Upon Element. .. 34

4. Values of Calculated Spectral and Flame
Compositional Parameters ... . ... 44

5. Values of Spectral and Flame Compositional
Parameters Taken from Literature . . . . 50

6. Specific Components Used in Experimental System.
for Measuring Limits of Detection. . . . 58

7. Experimental Conditions and Limits of
Detection Obtained for 21 Elements Using the
Continuous Source. . . . . . . . 61











LIST OF FIGURES


Figure Page

1. Theoretical curves of growth . . . ... 13

2. Instrumental set-up for the measurement of the
a parameter. . . . . . . . . 26

3. Experimental curves of growth for Zn, Cd, and
Mg . . . . . . . 38

4. Experimental curves of growth for Ag, Cu, and
Na . . . . . . . . . 40

5. Illustration of test for location of high
density asymptote and a parameter. . . . 43

6. Experimental set-up for determining limits of
detection with a continuous source . . . 57

7. Analytical absorbance curves for Ag, Cu, and
Na obtained using a continuous source. . .. 68











INTRODUCTION


Atomic absorption flame spectrometry occupies a

unique position among analytical absorption (optical)

techniques in that it is the only one which does not use

a continuous source of radiation (e.g., tungsten or xenon

lamp) for making measurements. Instead, a line source (e.g.,

hollow-cathode discharge tube or electrodeless discharge

tube) emitting very intense radiation over a very narrow

range of frequencies is used.

The method of atomic absorption spectrometry was

used in astrophysics for investigation of the composition

of stellar bodies. Walsh (41), in 1955, indicated that

atomic absorption spectrometry should be a useful technique

if a flame cell were used to atomize the sample and a line

source was used to excite the atomic vapor. However, in

his classical paper, Walsh not only surveyed the technique

and equipment needed to perform analyses using a line

source, but also indicated that a continuous source might

have analytical use. He decided that because a mono-

chromator of very high resolution would be needed to resolve

the atomic lines under investigation when using a continuous

source, a line source of radiation would be easier and much









less expensive to use. In addition, in this paper he pre-

sented equations relating the decrease in the peak intensity

of the radiation emitted from the line source to the

concentration of solution aspirated into the flame. He

proved that the measured absorbance when using line sources

in atomic absorption analysis was linear with atomic

concentration of the sample vapor in the flame gases, and

that the technique should be extremely sensitivic, chat is,

limits of detectabilities in the ppm range. Because of

these interesting and useful results little work on sources

other than line sources was carried out during the next few

years. If Walsh had not obtained such excellent results

and had not deemphasized the use of a continuous source,

atomic absorption analysis might have easily developed

along such lines. Astrophysicists such as Ladenburg and

Reiche, and van der Held and Ornstein (28,37) in classical

experiments measured the amount of energy removed from a

continuous source of radiation to determine many classical

atom.parameters. Expressions for this energy parameter

(called total absorption) are well established (28), and in

addition to being directly proportional to the absolute

atom concentration for dilute atomic gases present in the

flame, are independent of the resolving power of the spectro-

graph.










Developments in atomic absorption analysis using a

line source have been numerous and varied. Advances con-

cerning the optical set-up, burner design, flame gases used,

and,most important, in analytical applications have tended

to make atomic absorption flame spectrometry a more useful

analytical technique. Relatively few advances in the line

sources have been made, and those that have been made, are

aimed at incorporating more than one metal into a line

source to enable multi-element analyses to be performed and

to increase the intensity of these sources. A few but

significant number of developments have occurred in atomic

absorption analysis using a continuous source. Gibson,

Grossman, and Cooke (16), in 1962, investigated the possi-

bility of using a continuous source for analytical measure-

ments. They concluded that a medium resolution monochromator,

when combined with a scale expansion technique, would provide

sensitivity comparable with the use of a line source.

Recently Ivanov and Kozireva (22), and especially Fassel and

co-workers (11,12) have demonstrated that excellent sensi-

tivities are possible when using a continuous source.

With this progress in mind, the aims of this dis-

sertation are then:

(1) To establish the mathematical relationship be-

tween atom concentration and measured signal when using

a continuous source; verification in the form of working









curves for twelve elements will be given. This working

curve is unique, not only in its shape which allows the

analyst to detect any deviations from linearity quickly,

but in the information concerning fundamental atom para-

meters which can be obtained from it; such parameters as

the a parameter or damping constant (ratio of Doppler and

collision half-intensity widths), absolute atom concentra-

tion, atom formation efficiency factor, and the total half-

intensity width of the line for the atom of concern can be

obtained; a discussion of the equipment and procedures used

to measure data for preparing the working curves as well as

for associated parameters will be given.

(2) To continue the development of the quantitative

aspects of atomic absorption using a continuous source;

limits of detection for twenty-one elements using an experi-

mental set-up which provides maximum versatility for per-

forming analyses will be given.











EXPERIMENTAL MEASUREMENTS DESIGNED TO ESTABLISH THE
RELATIONSHIP BETWEEN THE MEASURED SIGNAL AND THE
ATOMIC CONCENTRATION WHEN USING A CONTINUOUS
SOURCE OF RADIATION


Introduction

When performing quantitative atomic absorption

measurements using a line source of radiation, the working

curve prepared is usually a plot of absorbance versus solu-

tion concentration. If a line source with a half-intensity

width less than the absorption line half-width is used, the

signal measured corresponds to variation in the maximum

absorption coefficient at the central wavelength of interest.

Because absorbance is proportional to the atomic absorption

coefficient, the working curve is linear only as long as the

absorption coefficient is proportional to solution concen-

tration.

When a continuous source of radiation is used, the

wavelength interval of continuous radiation isolated by the

monochromator depends upon the resolving power of the mono-

chromator. For the case of the medium resolution mono-

chromator used in this study, the spectral band width will

be much larger than the line width of the absorbing atoms

in the flame. Therefore, the measured absorption signal










will correspond to a function of the absorption coefficient

integrated over the spectral band width of the monochromator

and will always be proportional to concentration.

As seen from this brief comparison, certain basic

differences exist between the absorption signal measured

using a line source and a continuous source. Because of

these differences, this investigation was carried out to

determine if a more accurate and useful relationship (than

absorbance) existed between solution concentration and

measured signal when using a continuous source of radiation.

Theory


In order to indicate the similarities and the dif-

ferences in the use of a continuous source and a line source

in atomic absorption spectrometry, it is assumed that the

basic equipment consisting of a flame cell, a monochromator,

and an electrometer-read-out system are used in both cases.

Consequently, the instrumental proportionality factor Z,

relating read-out voltage to intensity of radiation reach-

ing the entrance slit of the monochromator, will be the

same in both cases.

All comparisons are made with respect to the type

of monochromator used in this study: a medium resolution

monochromator capable of isolating a single line, but not

capable of resolving the spectral line profile. This means









that the spectral band width of the monochromator s, is

considerably larger than the absorption line half-width

A T. In turn, the absorption line half-width is assumed to
be larger than the half-width of the line emitted by the

line source, AN.

Atomic absorption measurement with a line source

The photodetector signal due to radiation emitted by
the line source passing through the flame gases with only

blank solution being aspirated is given by


0I = / 7 (1)

where J, is the intensity per unit of wavelength. The

signal from the radiation passing through the flame with

sample solution being aspirated is given by



S Z-L (2)
N
where L is the path length in the flame.

In general, the atomic absorption coefficient k ,
is a complex function of wavelength and is described by the

following set of formulas (30):










\ = 4 Sc1,v ) (3)

ko ^7 2,.e1 )" 0 N/ (Li.)
o ~2- Al Ao NYC


Ak- = c T.,2- (5)
D c M

co


a = ay1 J
S(c~,v) r 2 V-. (6)


where e and m are the charge and mass of the electron,
c is the velocity of light,

Xo is the wavelength at the line center,
f is the oscillator strength,
N is the concentration of absorbing atoms in the flame,
T is the flame temperature,
R is the gas constant,
M is the atomic mass,

AAo is the Doppler half-intensity width of the absorption
line,

a is the damping constant, given approximately by L
AkL is the collision (Lorentz) half-width of the
absorption line,

and v is equal to 2. (-
A A










-'-jio o (*a v) describes the variation of i. over th
A
..:.. line., oweve, the integration i

u -...;i. ,::-o;ncOs over the emission line width,- k., nly c

;:ich is generally ,much smaller than the absorption line

.ith. If woe replace 1 with





.huo 1;: 'r<:ksents the average absorption coefficient over

-" -o;rce line iddth A, and v is an average over the

j from zero to AXNT, then the absorbance is given b;"


;,, n. = (8)


a for .al. concentrations, when AL ( / ,

V, ...L-


.. - < (>v)L -A0


S llo fo uaions 8 and 9 that if a line sour-c

o .-. i'n ato.-ic absorption spectrometry, such a plot

.ho.i pro-duce a straight line as long as the atom concen-

ui ir th ..e .fla.de is proportional to its concentration

in so..utic W WLon a very narrow line. source is usco. (i.c

.\ K K v t' 0), this straight line should extonl

c.vr an e ;-trely large concentration range; naeiiely, up to

tle poi;t whore rsonanct- broadening causes the damping

c;.stant to change (0) (for molar solution concentration).










Normally, linearity over an extended range of concentration

is not found. Deviations can be attributed to:

(1) Ionization and compound formation of the atom

of concern.

(2) A nonlinear relationship between atom concentra-

tion in the flame (N), and solution concentration (C).

(3) Variations in aspiration efficiency (43).
(4) The source line width is no longer negligible

when compared to the absorption line width.

Rubeska and Svoboda (34), and Vickers, Remington and

Winefordner (40) have discussed other sources of deviations

found in atomic absorption flame spectrometry.

Atomic absorption measurement with a continuous source

With a line source, the wavelength region of interest

is determined by the width of the source line; whereas, for

the case of a continuous source, this region is determined

by the spectral band width of the monochromator, s. Over

this small range of frequencies the intensity of the source

is essentially constant; therefore, the blank photo-

detector signal is given by

I = Z / J; = J s (10)

The photodetector signal due to radiation passing through

the flame with sample solution being aspirated is then









Ic = 2 /Bc-7A L E J^ALi (I)


therefore, the fraction of intensity absorbed in the flame

is given by


Odc -C C r= d (12)
I, 3S
I; s s

where the integration limits are 0 to o because -6c spectral
band width is assumed to be much larger than the width of the
absorption line and where AT is known as the total absorption

(28,50,36). Curves representing AT as a function of the
concentration N, depend on the value of the damping constant
a, and are referred to as curves of growth (21,28930,38).
AT, a, and curves of growth will be discussed in the next
section. An important characteristic of A which can be
seen from the curve of growth is, AT, is proportional to N
at low concentrations and proportional to N at very high
concentrations. Where k << I for the low concentration
region, when Loppler broadening is assumed predominant,
equation 12 becomes


ac. 4ALzd- o4 _ _) L (13)
c S 21~122 T / *

which is independent of the absorption line profile. This
can be seen from the similarity of all the curves of growth
(see Figure 1) for the low concentration region. The


























odl


O


I

O H



o *H
O o






r-1








*) 0

4, :




E-i
P 4H



0
'0






F4


4












ii
I!


















H














.-I
0




-P











0 CD
o do
0-0 \ \"


dr"
Ct
C


I









general expression for the absorbance A, is then


A, () -) (14)


As can be seen from this relationship, absorbance is a

complicated function of the concentration of the element in

the flame. According to equation 14, the absorbance is

proportional to the total absorption AT, only for small
A
values of the ratio On the other hand, the fraction

of intensity absorbed in the flame ac is always pro-

portional to the total absorption, but will be linear only

over the linear portion of the curve of growth. De Galan

(7) has shown that both types of working curves absorbancee

or relative absorption versus concentration),when prepared

from measurements made with a continuous source, begin to

slope off when more than 10 per cent of the radiation is

absorbed in the flame. At lower values of relative absorp-

tion, linear expansion of AT in equation 14 is valid.

Therefore, both types of working curves will show a similar

linear range over the low concentration range.


A discussion of the curves of growth, total absorption (AT),
and the damping constant and present means of calculation

To establish the validity and to provide a better

understanding of these parameters, a discussion of the










general nature and present means of calculation is presented

in this section. The discussion of the value and use of

these parameters in this study will be presented in a later

section.

Total absorption (A ), as defined by Ladenburg and

Reiche (28), is the fraction of energy removed over the wave-

length interval of the spectral line from a continuous

spectrum by atoms in an absorbing column of gas. It is

given mathematically by the expression


AT f=I-(-A )--, (15)

Minkowski (29), in a series of experiments, showed this para-

meter to be independent of the slit width of the monochromator

within the limits of experimental error.

The curve of AT plotted against the absolute number

of absorbing atoms is called a theoretical curve of growth.

Classically, this plot was used in experiments to determine

many fundamental parameters concerning the atom; some ex-

amples are the number of dispersion electrons associated

with the emission and absorption of a particular line, and

the natural lifetime of an atom. As seen from the theoreti-

cal curves of growth in Figure 1, each curve is characterized

by a linear range where AT is proportional to N in the low

concentration region; the curve gradually slopes off in the

high concentration range to become proportional to N .









While each curve is characterized by slopes of 1 and 1/2,

exact position of each curve is dependent upon the damping

constant or a parameter. This constant was previously de-

fined in equation 6 as


a = (6a)


Until recently, theoretical corves of growth were available

for only a few scattered a parameters (33). Recently

van Trigt, Hollander, and Alkemade (38) provided useful

calculations for preparing theoretical curves of growth for

a parameter values ranging from 0 to 10, with the values

from 0 to 1 given in 0.1 units. The latter range will be

of great use to flame spectroscopists because of conditions

found in the flame.

Interest in the a parameter stemmed from the funda-

mental data which can be calculated from it. Information

concerning the interaction of perturbing and emitting

particles (i.e., the optical cross-section), the resultant

wavelength distribution of emitted intensity (i.e., the

line profile), and in combination with a curve of growth,

the absolute atom concentrations, and efficiency of atom

formation in (e.g.) flames, are just a few of the more


From now on, all formulas will be given in terms of
frequency units. Those formulas previously calculated in
terms of wavelength units can be converted by the following
expressions: d = C/% and A) = Cc/X)AA.









important parameters which can be calculated. Experimental-

ly, a is a difficult parameter to determine; therefore, most

measurements are made on the emission intensity from flames

of low burning velocity (e.g., acetylene-air). In general,

few a parameters have been measured (even in these flames)

because of the restrictions placed on the types of flames

and flame conditions which can be used to prepare curves of

growth in emission from which they are determined. The re-

quirements for the preparation of the curves of growth in

emission are (21):

(1) A homogeneous distribution of flame gas and metal

species.

(2) A homogeneous distribution of temperature over

the region of observation.

(3) Complete elimination of self-reversal.

(4) Complete elimination of ionization.

(5) Linearity of aspiration and photodetector-ampli-

fier read-out.

For these reasons, no measurements have been made in flames

of high burning velocity (e.g., acetylene-oxygen and

hydrogen-oxygen) which are of use in analytical flame

spectrometry.

Two methods based on measurement of the variation of

intensity of radiation emitted by atoms in the flame for

preparing curves of growth are available for accurate de-

termination of the a parameter. The newest method developed










by van Trigt, Hollander, and Alkemade (38) utilizes experi-

mental and theoretical curves of growth in combination with

an experimental duplication curve to determine the a para-

meter and absolute atom concentration directly. The

readers attention is called to this article for a more de-

tailed discussion of the method used.

The older and more widely known method is the one

developed by Hinnov and Kohn (18,19). In their classical

papers, the authors presented equations for the high and

low density asymptotes of the curve of growth which take

into account their dependence on the a parameter. They

showed that the absolute ordinate of the point of inter-

section of the asymptotes (see Figures 3 and 4) is



log AT 2 = (16)

Thus from a knowledge of the temperature of the flame and a

series of experimentally measured AT values, the a parameter

could immediately be determined. The AT values necessary

to prepare the experimental curve of growth were determined

from the measured variation of intensity from atoms in a

series of metal solutions aspirated into a flame of low


In more recent papers by Behmenburg and Kohn (1,2),
the effects of hyperfine structure due to nuclear spin and
isotopic shift on the value of the ordinate were studied.
They found the ordinate value equal to log na, where n is a
constant, the.value of which is dependent upon the atom under
consideration.










burning velocity. The measured emission intensity was con-

verted to total intensity (absorption) by comparison with

the radiation from a standard lamp.

The curve of growth prepared in this manner is an

experimental curve of growth because the abscissa of this

plot is solution concentration. The intersection point of

the high and low density asymptotes is also necessary for

converting experimental solution concentration to absolute

atom concentration in the flame gases.

The relationship*


K = 4- (17)


allowed calculation of the proportionality constant K which

related the theoretical and experimental curves of growth to

CI, which is the solution concentration at the intersection

point. Therefore, at any solution concentration C, the

concentration of atoms in the flame capable of absorbing the

line under consideration was given by



N = eC AdJ KC (18)
j ZxL >fL -22T-

This value of Nj represents the population in energy level j,

and can be converted to the total number of free atoms of

The proportionality constant K is labeled Q in
Hinnov and Kohn's (18,19) work.










the element by using the Boltzmann distribution relation-

ship.

Once the a parameter and absolute atom concentration

have been determined, many other parameters of interest can

be calculated.

The efficiency of atom formation PI, at the inter-

section point is calculated from the following relation-

ship:


N! N
S -N I (19)
I Total x lO2 (c

where NI, is the absolute atom concentration at the inter-

section point;

Total, is the total number of atoms present regard-
less of form;

S is the solution flow rate in cc./min.;

n298 and nT, are the total number of moles of flame
gas products present at 2980 K and at the flame temperature

T;

Q is the flow rate of unburned gases in cc./min.;

and

S, is the aspiration efficiency as defined by

Winefordner, Mansfield, and Vickers (43).

As defined, PI, is a factor used to account for

atomic losses due to ionization and dissociation of the salt








introduced and compounds formed between the atomic species
of interest and various gas products.

The collision (Lorentz) half-intensity width AL

(30,36) is given by

)L (20)

and the total half-intensity width of the line Av) (30,56)
is given by


A = (+ C& ) ) (21)

Normally, natural broadening and resonance broadening will
not be significant when compared to Doppler and collisional

broadening. Natural broadening is on the order of 10 A,
resonance broadening does not become appreciable until
molar solutions are used, Doppler and collisional broadening
are on the order of 101 102 A. For this reason natural
and resonance broadening will not be considered in this
paper.
The effective cross-section for collision (Lorentz)
broadening (30,36) -L' is given by


2 A JL
o- L ,`- ,5 10 P+ > (22)

where P,, is the pressure on the system during measurement
(normally taken to be 760 mm);







22

M, is the atomic weight of the absorbing species; and

Ma, is an effective molecular weight of the flame gas
species including water which causes collision

broadening.

This parameter (p-L) is of interest because it can be used

to indicate the nature and type of interaction between per-

turbing and emitting species.


Experimental Conditions


As can be seen from the theory developed for the

signal measured using a continuous source, the absorption

method can be used to determine total absorption (Am) di-

rectly.* A valid test of the relationship would be to

prepare working curves (experimental curves of growth), to

check for correct shape (i.e., the correct slopes), and to

calculate reasonable a parameters. The method could then

be used to calculate other parameters such as atom formation

efficiency, total line width, and effective collisional

cross section; however, these values could not be used as

conclusive proof of the method because they represent the

first to be calculated in this type of flame.

The preparation of the curves of growth from absorp-

tion measurements also offered other advantages which

A,/s is obtained from the experimental curve and is
converted to AT by multiplying by the spectral band width s.









overcome some of the restrictions inherent in the emission

method.' Some of these advantages are:

(1) Self-reversal will not influence the value of a

measured absorption signal.

(2) For those atoms which do not form compounds or

ionize readily, small variations in temperature will have

little effect on absolute atom concentration (8).

(3) Atoms which emit radiation too weak to be detec-

ted reliably can still be measured using an absorption

technique.

(4) The absolute number of atoms producing the ab-

sorption is obtained directly. Generally the total number

of atoms producing absorption is approximately the same as

the total number of atoms in all states. However, if this

situation is not valid, then the atomic concentration calcu-

lated from equation 18 can be converted to the total number

of atoms in all states by use of the Boltzmann equation. An
O
example of this case is Ni (3414 A) where the absorption

transition originates from a low lying energy level.

In this study, curves of growth will be prepared for

twelve elements from measurements of the variation of the

fraction of intensity absorbed with concentration of

aspirated solution using a total-consumption aspirator burner

for five flames of interest in analytical flame spectrometry.

The choice of hydrogen and acetylene as a fuel and

oxygen as the oxidant, and their respective flow rates to










produce stoichiometric or fuel-rich flames was determined

by their relative usefulness for analytical flame spectrom-

etry. The argon-hydrogen-entrained air (Ar/H2-E.A.) flame

was added to this list because of recent successes with

this flame in this laboratory (39,46).

With respect to the requirements for preparing curves

of growth in emission (referred to earlier), those not

covered by the inherent advantages of the absorption method

will be met by:

(1) Reducing ionization by addition of an ionization

buffer to solutions of those metals with ionization poten-

tials below 5 e.v.

(2) Reducing the variation of temperature and compo-

sition in the flame region viewed by judicious choice of

the location and size of the flame region viewed.

The a parameters and absolute atom concentrations

will be calculated from the curve of growth by the method

developed by Hinnov and Kohn (18,19).


Description of the experimental conditions

(a) Conditions for measurement of the a parameter.

The instrumental set-up used for making the flame

absorption measurements is shown in schematic form in Figure

2. The specific components used in the experimental set-up

are given in Table 1, and the operating conditions for the

measurements are given in Table 2.


























c(l


4,
-P



0



4-'
p





















0
P42


-P
H





4.




(H
rd

















,4
ab








-P










g-p

























o

4-l a

C;)

O C






L~i





S0
r-y























iC-
O
cJ 0
0
r-'





I--!
;-
0 C


Go









TABLE 1

SPECIFIC COMPONENTS USED IN EXPERIMENTAL SYSTEM FOR
MEASUREMENT OF THE a PARAMETER


1. Spectral Continuum




2. Optics


3. Monochromator+


4. Detector-Power Supply




5. Amplifier-Readout
Electronics


Xenon arc, 150-watt (Englehard,
Hanovia, Newark, N. J.) powered
by a regulated a.c. supply
(Sola Electric Co., Chicago,
Ill.).

Single pass, chopped at 320
cps. Chopper consists of a
disc with eleven equally
spaced holes rotated by an
1800 rpm synchronous motor
(Bodine Electric Co., Chicago,
Ill.). L1 and L2 are quartz
lenses.

Jarrell-Ash, Model 82000, 0.5
meter Ebert Mount, grating
spectrometer (Jarrell-Ash Co.,
Waltham, Mass.). Grating is
ruled for 1250 lines/mm. and
is blazed at 5000 A (for Zn,
0
Cd, and Mg a 3000 A blazed
grating was used).

EMI 9558 QBophotomultiplier
(1650-9000 A). Regulated d.c.
power supply (No. 418A, Fluke
Mfg. Co., Seattle, Wash.).

A.C. Photomultiplier output
signal was fed into an O.R.N.L.
No. 7 a.c. amplifier turned to
320 cps. The plate and fila-
ment voltages were taken from
a dual power supply (No. R
100 B, Philbrick Researches,
Boston, Mass.). The a.c.
signal was rectified and the
d.c. signal was recorded on a
potentiometric recorder (Model
TR, E. H. Sargent and Co.,
Chicago, Ill.). A scale ex-
pansion technique was used
where necessary.










6.' Gas Pressure and Flow
Regulation






7. Aspirator-Burner


The gas flow is regulated by
a Beckman High Precision
regulation unit (No. 9220,
Beckman Industries, Fullerton,
Calif.). The resultant flow
is monitored by rotammeters
(No. 4-15-2 Ace Glass Co.,
Inc., Vineland, N. J.).

Total-Consumption Type (Carl
Zeiss Inc., New York, N. Y.).
















" 0 00 CT.
O





En
S CM4 CM 1 r-4 -4







* CC


r-4


oI
CM
00



el
N






rL

4


CM CM


o- -M


Ln 0
* *
CM u-


Z
PL4
>4














0
E.-











H
Fn4



0








E
('
CM z







pq M

0


*









0 0





C CN











I !



o o
, *
9 c




-n Ln


C'4 -
S O4

o o



i N
C U'


('4 C'-


,O * H


0 0
0 C- N4
CM4 CM4 CA ..
O0 0 4 M
NM C4 p- C4 CM(
a M < (u *


CM4 CM4
0 0


0 0
'l- u'




CN CM

a a

0 0
SONC
r-4 r


41-
4)







41

(31
an







-C
4-)

x

0






Sa)
co










4)




< m
4 -












4J
S co




*d
U 1

nl M
.4-
e ^


C 4.


4
4.4




0
41 X
4) X
rd -


x 0


M I
0 co






u XC
0I 0






0 I


E -
*H CD
*^ 3



e u
0 *r





I =I



v h
(0 ,C









Stock solutions of 20,000 ppm for each of the twelve

elements were prepared by dissolving the appropriate salt

(chloride or nitrate) in aqueous or the metal in acidified-

aqueous solution. More dilute solutions were made by suc-

cessive dilution of the stock solution. The ionization

buffer salt (CsNO3 or KNO ) was added to each dilution of

the stock solution for the alkali metals in quantities as

prescribed by Hoffman and Kohn (20) (i.e., 2 x 10-)_ X CO3

for Li and Na, 2.5 x 10l i K2 CO3 for Rb, and 1 x 10-1

CsNO for K).

The flow rates for the gases used to produce the

flames used in this study are given in Table 2. The region

of the flame chosen for investigation in the total-consump-

tion aspirator burner was, in all cases, located a short

distance above the inner cone in the interconal region of

the flame (see Table 2 for respective heights). This region

was chosen to insure that equilibrium statistics controlled

the concentration of the species present in this region (17).

The entrance optics and slit height of the experi-

mental set-up were used to control the size of the region

viewed and to reduce it to a minimum according to the

restrictions discussed by Hollander (21).

The temperature of the interconal region of the flame

was measured by the line-reversal method for the Ar/H2-E.A.

and H2/02 flames. The line-reversal method of Fery (15) as










discussed by Gaydon and Wolfhard (15), is based on the

assumption that, on introducing metal atoms in the flame,

statistical equilibrium is established between the electronic

degrees of freedom of the metal atoms and flame gases. The

metal atoms thus emit and absorb their spectral lines as

thermal radiators. The line-reversal method is based on the

following principle: If a blackbody is placed behind a flame

containing sodium atoms which are emitting the yj,., sodium

D doublet, and a spectrometer is aligned to see both the

blackbody and flame simultaneously, then there will be some

temperature of the blackbody at which its brightness for the

specific wavelength region equals the brightness of the

blackbody transmitted through the flame, plus the brightness

of the D lines from the flame. At this temperature, only a

continuous spectrum of the blackbody will be recorded. At a

lower temperature of the blackbody, the sodium line will

appear in emission superimposed upon the continuous back-

ground; and at a higher temperature, the sodium line will

appear in absorption. The brightness temperature of the

standard tungsten lamp was calculated as a function of lamp

current from data for the radiance at 35 amperes supplied as

a calibration with the lamp and the emissivity of tungsten
O
at 5890 A calculated by de Vos (10).

The two-line method was used for the hotter C2H2/02

flames and also for the H2/02 flames in order to compare

the results of the two methods.










The Ornstein two-line method (3) involved the

measurement of the intensities of two iron lines; Fe 3734.87
0 0
A, and Fe 3737.14 A, from which the temperatures can be

calculated by the following formula:



log log A + (22)
Ib ASb X-


where Ia and Ib are the relative measured intensities at
O 0
ha = 5734.87 A and Xb = 3737.14 A lines, respectively; Aga
and Ag, represent the product of the transition probability

and statistical weight for the two lines (the ratio of Aga

to Agb was calculated from data given by Crosswhite (6)

and found to be equal to 11.'6); Ea and b are the energy

of the transition corresponding to the line; k is the

Boltzmann constant; and T is the flame temperature of

interest.

Crosswhite (6), and Broida and Lalos (4), have dis-

cussed some of the requirements for use of this method. A

few more of the more important requirements are:

(1) Both lines chosen must have negligible self-

absorption and self-reversal or at least have them of equal

degree.

(2) Lines must be close enough for rapid but accurate

scanning.

(3) Both lines must be close enough together to

insure that the photocathode has essentially the same









response to both lines or a suitable correction must be made,

The agreement of the temperatures obtained by the two metho&G

was excellent and within experimental error. The experi-

mental set-up used for the temperature measurements was the

same as shown in Figure 2, except that the continuous source

was replaced by a standard tungsten lamp. The temperatures

determined for these regions are given in Table 2.

The spectral band width o h,;Lu onochromavor (see

Table 3) was determined by scanning the 3650.15 3654.83 A,
O
and 5769.59 5790.65 A lines from a low pressure Hg dis-

charge lamp. The relative recorded distance between the

two lines was converted to a known distance, and this scale

was used to measure the half-intensity widths of the lines

involved. The relative standard deviation in measuring the

spectral band width was less than 10 per cent for all slit

widths used. This method is preferred to the scanning of a

single line (e.g., the iron lines used in the temperature

measurements) because of the difficulty encountered in

reproducing the exact scanning speed. The experimental set-

up used for this measurement was the same as that shown in

Figure 2, except the total-consumption aspirator-burner was

replaced by the Hg lamp.

Because metal concentrations ranged from 1 104 ppm,

the output of the detector-amplifier system was checked for

linearity of response by use of neutral density filters of













TABLE 3

VALUES OF PARAMETERS DEPENDENT UPON ELEXNT


0
(A)

6707

5890

7665

7800

3247

3281

2852

4227

4607

3414

2138

2288


f

0.75

0.67

0.67

0.67

0.30

0.51

1.11

1.55

1.80

0.11

1.30

1.25


Sl it
Width (p)

80

210

300

200

12

12

40

12

12

12

40

40


Element

Li

Na

K

Rb

Cu

Ag

Mg

Ca

Sr

Ni

Zn

Cd


Specural
Band Width (A)

0.90

3.14

3.66

2.92

0.38

0.38

0.41

0.38

0.38

0.38

0.41

0.41









known transmission and found to be satisfactory. The rela-

tive error due to deviations from linearity of aspiration

was also checked and found to be less than 3 per cent for

all solutions with metal concentration less than 1.5 : 101

ppm.
b. Conditions for measurement of the atom efficiency

factor, P.

The aspiration efficiency C is a meaasU u th.

ability of the flame to remove the solvent from the salt

solution aspirated into the flame (31,43). As such, it is

a difficult quantity to measure because of its strong de-

pendence upon height in the flame and flame gas composition.

Parsons and Winefordner (51) have suggested a method of

measuring ( based on a comparison of the measurements of

the light reflected from water droplets aspirated from the

burner, with and without the flame. Using their method,

the aspiration efficiencies for the five flames under

investigation for the specific region of interest were

measured (see Table 2).

The value of the path length of radiation through the

flame (L) for a total consumption burner (see Table 2) is

difficult to measure due to the irregular shape of the turbu-

lent flame. The value of L can be approximated by measuring

the length of the path over which continuum radiation is

scattered when solution is aspirated into the burner (flame

not burning).









The solution flow rate 1 was determined from tho

time required for aspiration of a known volume of salt

solution (see Table 2). The standard deviation in all cases

was less than 1 per cent.

The value of Q, the flow rate of unburned gases, can

be calculated from a simple conversion of the flow rates of

gases used to produce the flame (see Table 2).

The value of the paramoor n2 /n which corr/ts

for the expansion of the total number of moles of flame

gases for the temperatures indicated was calculated and

found to be equal to the value determined by Winefordner and

Vickers (44,45). The value of this ratio is 0.83.


Experimental Results


Curves of growth were prepared from absorption

measurements for each element in each of the five flames.

Each point on the curve represented the average value of

nine determinations with a relative standard deviation of

less than 1 per cent. Examples of several curves are given

in Figures 3 and 4, for Zn in C2H2/02 (stoichiometric),

cadmium in H2/02 (fuel-rich), and Mg, Na, Cu, and Ag in

Ar/H2-E.A. From the value of the total absorption A., taken

from the intersection point of the asymptotes of a specific

experimental curve of growth and the Doppler half-intensity

width calculated from flame temperatures, the a parameter

















Fig. 3.-Experimental curves of growth for Zn, Cd,
and Mg.

One Zinc, 2138 A line, in C2H2/02 ST.

Two Cadmium, 2288 A line, in H2/02 F.R.
O
Three Magnesium, 2852 A line, in Ar/H2-E.A.

(In experimental and theoretical coordinates.

Note, the right ordinate is AT'f-/A o

where AT and AiD are in units of sec-1

However, the same ordinate values would

result if ATr l/X, were plotted, where

AT and AD are in wavelength units.)





















,&o I






















Fig. t.-Experimental curves of growth for Ag, Cu,
and Na.

(In experimental and theoretical coordi-

nates.)

One Sodium, 5890 A line, in Ar/H2-E.A.

Two Copper, 3247 A line, in Ar/H2-E.A.
Three Silver, 281 A line, in / .A.
Three Silver, 5281 A line, in Ar/H2-E.A.



























I I I I
2-Cd

-1.0





-0.01








It 0102 110 104

3-Ag
-.0


-9.01







10 102


10 10 4
I I


ATY ?
A Z2'


.


L









was calculated for the specified conditions. The value of

the a parameter and the location of the high density

asymptote were then checked by a method described by

Behmenburg and Kohn (1,2). An illustration of this check-

ing procedure is given in Figure 5. The theoretical curves

of growth used in the checking procedure were prepared from

calculations given by van Trigt, Hollander, and Alkemade

(38). Values of the Doppler half-intensity width and the a
parameter are given in Table 4.

From the value of the solution concentration CI, at

the intersection point, the absolute atom concentration I,,
.A.
is calculated from equation 18. It should be noted that

the values of the oscillator strengths P used in these

calculations were taken from the present literature and

should be considered weighted values. The values for the

alkali and alkaline earth metals used in this study are well

established. The value of f for nickel, however, was

calculated from the gf value given in Corliss and Bozman

(5). Errors in an f value will produce direct variations
in absolute atom concentration NI; however, in most cases

in this study, variations in f are of the order of experi-

mental error for this study. The values of used in this

study are found in Table 3. The calculated values of NI

are found in Table 4.












Fig. 5.-Illustration of test for location of high
density asymptote and a parameter.

The following example illustrates the effect
of an erroneous choice for the location of high
density asymptote. A plot of an experimental
curve of growth representing the true location
of the high density asymptote and correct a
parameter value of 0.25 is given. From the
points U, V, and W at relatively low concen-
trations, one may be tempted to draw the upper
density asymptote. The asymptote drawn through
these points deviates only about 2 per cent
from the slope of 1/2, and gives an a parameter
at the intersection point of the low density
asymptote of 0.35. For the a parameter of
0.25, the logarithm of the total absorption at
which the theoretical curve approaches the
high-density asymptote equals about 0.9 and not
0.2 as is shown in the figure for erroneous
construction. The value at which the logarithm
of the total absorption for the theoretical
curve a = 0.35, should approach the high density
asymptote is about 1.2.


























I I I


1.0
- 0.9


I 10
log


iC
C (ppm)


10&


-= Q24,














oM 4 CM OO Co n CV rI r' cr .-i C n n


hlI.)rl0
e 4NO0


P-4



0
H
E-l

0
-I,


0









--4



C,.









0


u
td


cr) oo Mr-













mn) 0 N m'












c~c-ct.


0-4


000


4 Icno )-1 4C<

CM CM CM 1n m
04 C C





NNNON cr~


-4 O
0- 00
00 r- -I
* -4 C*


-41-Ii ClJ r


cn 0o CM4 -It Ln
Cn Cn CMi C CM





E* H


00
0 0 C\ cM


0r- -
-4-4-4


r-


r-4 C4 cn -( )


C4M CM CM









co e












if)

-4-44-4r-4







1-1 in CM k.0 (O

00000





o -o oC o


























14 CM en t-n
*****3


000
.0 C0


C4 00

00
,-i


* 4


rCM

















































00000



















uLf
C'M CM % CM C)





a0 in M r Co

























00
00= co J('i
Z =
A N 4 C C
I- 1 m O
NNN\'
OO. MI







CM C M'~ ~


00000









N e 3

















oo o oo
00000
* * a


oM O n >o ~


*4 0 *
i-< 0 i- D C


* * '^-<-\


r- CM o -*












00000























00000







00
SM CY) r







000 N -

00000


CM4 00 O
c,4 -T i


tO\os


r-c0-
C L


00-4-

s W


0 0
000

000


OOOc

000
000
000





oDo

-4
oo


-4 0
C***D


Cr- Vn
* *















CNOm O Mc 4 r 00

























e e a .oo o o

rCl 4 C4 r4 C4 r










C* -I %
* e *l e**


\0


Om-4




* * -
* ** *



NNo < r


00








00


00
se9


000


uir



















00000
in***


u00- C

C* * -


Cs n





SCE-1N NN

C(n z CM4 C4
00


CM4 C4 00 C CM4
~N~N1If


f- r i r- -t
13 -t %D" ID %.>










The effective molecular weight Ma, of the foreign

gas species producing collisional broadening represents a

weighted molecular weight calculated from all gaseous

species present in the flame, and was calculated from flame

dissociation data given by Zaer (47). The effective

molecular weight for the Ar/H2-E.A. flame was calculated

assuming complete combustion of 10 per cent of the hydrogen

introduced. Using these effective molecular weight values

(see Table 2), values of A L, ALT, and
and are found in Table 4.


Discussion

Discussion of errors

Before reaching any conclusions with respect to the

experimental data determined in this study, a discussion of

errors is necessary. However, because of the indeterminate

nature of some of the errors, a detailed analysis of the

total error in each case will not be given. Only an esti-

mate of the order of magnitude of the various sources of

error will be given where possible.

Errors associated with calculation of the a para-

meter.-The relative error in measurement of the spectral band

width was less than 10 per cent. A temperature variation of

1000 K (a deviation of about 4 per cent) is needed to produce










a noticeable variation in the Doppler half-intensity widths.

Probably the largest source of error is in drawing the

asymptotes for the curve of growth to find the intersection

point. Hinnov and Kohn (18,19) have commented upon this

error, and concluded that the error limit for an experi-

mentally determined a value due to the choice of the

location of the asymptotes should not exceed 10 per cent.

However, the high density asymptote depends heavily on the

absorption values at the highest concentrations, and so this

is the region of largest variation of these values. Depen-

ding on the location of the intersection point, deviations

as high as 20 per cent are possible, and so the maximum

relative error expected for the a parameter in this study

is about 25 per cent.

Errors associated with calculation of NI and 3i.-The

magnitude of the error introduced in the location of the

intersection point will manifest itself as a similar error

in CI. The difficulty in determining the effect of this

error on NI, lies in estimating the deviation in the effec-

tive flame path length, L. It is felt that variations as

high as 50 per cent may be encountered. Similarly, the

calculation of the atom formation efficiency factor P5,

will be expected to show relatively large deviations due

to the compounding of errors from previously calculated










parameters. The relative error in estimating the aspiration

efficiency ( is probably 25 per cont. Therefore, NI and

PI, will have relative errors of the ordcr of two-fold.

Errors associated with calculation o ootce- nara-

meters.-Random errors were reduced whenever practical by

repetitive measurement.' Variations in A)L, and AJT can be

associated with variations expected in the a paramtor.

The effective collisional cross sectionc-L, can be expected

to show a somewhat larger variation than is found in the a

parameter due to addition of an indeterminate error in the

effective molecule weight of the perturbing gas species.


Comparison of results with literature data

Because of the dependence of the measured parameters

upon specific flame characteristics, it is impossible to

compare directly literature data to the results of this

study. The experimental data determined in this study were

used primarily to prepare the curves of growth by an

absorption technique and to calculate the a parameter.

Interpretations of other calculated data should be made with

reference to the absolute magnitude of the values given.

The values given in Table 5 for these parameters represent

(nearly in total) those which are available in the litera-

ture.












TABLE 5

VALUES OF SPECTRAL AND FLAME COMPOSITIONAL PARAMETERS
TAKEN FROM LITERATURE


Van Trigt,
Hollander, Alkemade (38)

a NxlO-13cc. 2
/cc. TL (A )

.29a 5.1 18

.45a 5.2 27
.38a 11.7 26
.33a 12.6 25
.41b 10.1 30

.78a 5.3 31


Element

Li

Na




K

Rb

Cu

.Ag

Ca


Sr


0.85
1.1

0.51
0.60


Kohn and
Co-workers
(18, 19, 20)
o2
a o-L(A )

.57c 46.5

.79c 59.7
.79d 65.9


1.19c

2.06c

.46c

1.03c

.62c
.57d

1.03C
.91d

.54c


60.4

79.3

46

83

56.6
57.3

66.0
64.8

51


aCalculated in a CO/air flame. The different values given
for some elements represents different mixtures of CO and air.

bCalculated in a C2H2/air flame.

Calculated in a C2H2/air flame.

dCalculated in a C2H2/air NO flame


eCplculated in a C2H2/air flame using a chamber-type burner.


.46a
.41a

.96a
.85a


de
Galan (9)

pe

.20

.50




.25



.97

.65

.14


.13


--









When preparing curves of growth and calculating a

parameters, the test developed by Behmenburg and Kohn (1,

2) is very sensitive to small deviations from the correct

a parameter. Any errors in calculating a or in preparing

the stock solutions appeared as obvious deviations from the

correct slopes of the working curve (curve of growth).

Perhaps the largest single source of error which produced

deviations in the working curve was the spectral band width

of the monochromator. Only when the slit width was in-

creased to a relatively large width would the curve of

growth show the correct slope in the high density region.

This apparent failure of total absorption to be independent

of spectral band width cannot be explained. Hinnov and

Kohn (18,19) used large spectral band widths in their

studies but offer no explanation for their use. One

noticeable effect of the large spectral band width was the

decrease in sensitivity in the low concentration region;

this was expected, and did not affect the establishment of

low density asymptote.

When a parameter values are compared, a good cor-

relation (see Tables 4 and 5) within experimental error of

this study is found for Li and K, with the data given by

van Trigt, Hollander, and Alkemade (38); and for Li, Na, K,

Cu, Ag, Ca, Sr, and Ni with data given by Kohn and co-

workers (18,19,20) for flames of comparable composition.

This is, indeed, promising for the method.










The BI and NI factors given in Table 4 and those

found in Table 5 are not readily comparable because of the

basic difference between the aspiration mechanism of the

two types of aspirator burners used. However, the PI

values given in Table 4 are considerably smaller than the B

values obtained by de Galan and Winefordner (9) (see Table

5) for the same elements in an air-acetylene flame of low

burning velocity produced by a chamber type aspirator burner.

No attempt will be made to correlate o-L values given

in Tables 4 and 5, nor will an attempt be made to calculate

values for this parameter from any of the present collisional

theories (e.g., Weisskopf-Lindholm Impact Theory). The

readers attention is called to the excellent articles by

Behmenburg (1), and van Trigt, Hollander, and Alkemade (38)

for discussion of the effects of variations in the nature

of the perturbing species on the collisional cross section.

The variations of the parameter found in this study from

element to element and from flame type to flame type are

attributed to variations in the concentration and type of

perturbing species found in these flames. For this reason,

these parameters are not corrected for the effects of

hyperfine structure due to nuclear spin and isotopic shift

and line broadening effects due to quenching collisions.

Data from this study can be used to indicate the

range of variation of the a parameter, effective collisional










cross section, and total line width for conditions found

in this type of flame. The a parameter will have a value

less than 1.5, an effective collisional cross section less
02
than 100 A and a total half-intensity line width on the
9 -1
order of 10 sec (i.e., approximately 0.01-0.1 A for a
0
hypothetical line at 5000 A wavelength). This is in line

with the conclusions reached by Parsons, McCarthy, and

Winefordner (32).

In conclusion, the inherent advantages of preparing

working curves (curves of growth) in absorption, coupled

with the predictable shape of these curves not only

establishes the validity of the method, but should be of

real use to the analyst. In addition, preparation of

curves of growth in absorption should make this method a

useful means for the study of many fundamental flame

parameters.












EXPERIMENTAL MEASUREMENTS DESIGNED TO EXTEND ANALYTICAL
APPLICATIONS OF THE CONTINUOUS SOURCE


Introduction


Atomic absorption flame spectrometry (using a line

source) has enjoyed great popularity in recent years. This

is primarily due to the broad applications of this technique

to the trace analysis of metals. Complete commercial

instruments are now available for performing absorption

analyses; also a multitude of commercial components are

available and these can be assembled to meet the analyst's

specific needs. However, with any instrument, the analyst

soon discovers limitations in his system, and these are:

(1) Choice of fuel and oxidant because of burner

design.

(2) Restriction to performing only flame absorption

analyses and not flame emission as well as flame absorption

analyses.

(3) And most important, the time and expense involved

in using line sources of radiation for nearly every element

of interest.

In connection with limitation (3) above, more speci-

fic problems may be encountered with a line source, some

of which are:









(a) time involved in optically positioning the lamp

for each elemental analysis;

(b) difficulty encountered in finding lamps of satis-

factory intensity, stability, and lifetime for

all elements of interest to the analyst; and,

(c) the inability to carry out simultaneous qualita-

tive and quantitative analyses (in most cases)

for more than one element.

With these limitations in mind, this investigation was

carried out to develop an experimental method which would

have maximum versatility without significant loss in sensi-

tivity of measurement for performing absorption measurements.


Experimental


Apparatus

The instrumental set-up used to make the flame ab-

sorption measurements is shown in schematic form in Figure

6. The specific components used in the experimental set-up

are given in Table 6.

As shown, the solid angle of radiation is first

reduced by the housing around the xenon lamp, or by the

baffle placed in front of the tungsten lamp. The radiation

is chopped and passes through collimating lens L1, where it

enters the tube and is passed through it by a process in-

volving multiple reflection (14). The resultant radiation




























CO







oC)
O-p
*dH





co


0*


0
1d 0
O *



co


0
pco





*p H









'57














CCID
~ eLl

cLi
Z:2
Q C ,C













v
P I CDr
J'2

r0






C CD
>0 C
^.^ ^/ ; \ s ^-











C-








I i
^ S



_s
t-. i-i-

^~C cs Q 3 *-|
a~C E^) u ?

<~ 1 e J __ ^
- c




*p^ -^ j. -. L-
5 i ^ ^

\^_ ^^^ _J

Y <" ^v \ (-
i S-^K^ -'c
\L V \ /-^










TABLE 6

EXPERIMENTAL SET-UP FOR DETERMINING LIMITS OF
DETECTION WITH A CONTINUOUS SOURCE


1. Spectral Continua.


2. Optics.


5. Monochromator.


Xenon arc, 150-watt (Eglehard,
Hanovia, Newark, N. J.) powered by
a regulated a.c. supply (Sola
Electric Co., Chicago, J1l.) used
for range of 2700-6000A. The
jacket surrounding the xenon lamp
has a connector for cooling air
and a baffle hole of 5/32" diameter.
Tungsten filament lamp (No. 2505,
Beckman instruments Inc., Fullerton,
Calif.) powered by a 6 volt storage
battery and used for range of 3500-
O
8500 A. A baffle with a 5/32" hole
was placed in front of the tungsten
lamp.

Single pass, chopped at 320 cps.
Chopper consists of a disc with
eleven equally spaced holes rotated
by an 1800 rpm synchronous motor
(Bodine Electric Co., Chicago, Ill.).
L1 and L2 are quartz lenses. L1 is
a collimating lens, 8,0 cm. focal
length. Flame tube is thick walled
Vycor, 12 inches long with a 1.6 cm.
O.D. and 1,0 cm. I.D. (Englehard
Industries Inc., Hillside, N. J.).
Tube was held in place by a labora-
tory clamp. The tube holder was
fitted with connectors to direct air
at the flame tube to prevent burnout
and to extend the lifetime of the
flame tube. A small hood was posi-
tioned over the flame tube and
holder to remove flame gases and to
cool the unit.

Jarrell-Ash, Model 82000, 0.5 meter
Ebert Mount, grating spectrometer
(Jarrell-Ash Co., Waltham, Mass.).
Grating is ruled for 1250 lines/mm.
and is blazed at 5000 A.o Reciprocal
linear dispersion is 16 A/mm. in
the first order.










4. Detector-Power
Supply.



5. Amplifier-Readout
Electronics.










6. Gas Pressure and
Flow Regulation.









7. Aspirator-Burner.


EMI 9558 QB photomultiplier (1650-
0
9000 A). Regulated d.c. power
supply (No. 418 A, Fluke Mfg. Co.,
Seattle, Wash.).

A.C. photomultiplier output signal
was fed into an 0.R.N.L. Model No.
7 a.c. (23) amplifier tuned to
320 cps. The plate and filament
voltages were taken from a dual
power supply (No. R 100 B, Phil-
brick Researches, Boston, Mass.).
The a.c. signal was rectified and
the d.c. signal was recorded on a
potentiometric recorder (Model TR,
E. H. Sargent and Co., Chicago,
Ill.).

Tank pressure is reduced by appropri-
ate two stage high pressure regula-
tors (The Matheson Co., Inc., East
Rutherford, N. J.). The gas flow
is then further regulated by a
Beckman High Precision regulation
unit (No. 9220, Beckman Industries
Inc., Fullerton, Calif.). The re-
sultant flow is monitored by rotam-
meters (No. 4-15-2 Ace Glass Co.,
Inc., Vineland, N. J.).

Total-Consumption type. Medium
bore (No. 4020, Beckman Instruments
Inc., Fullerton, Calif.).










is focused by lens L2, on the slits of the monochromator

where it enters and is dispersed. The aspirator-burner and

holder are mounted on a ring stand at a 450 angle to the

optical axis of the flame tube with the tip of the burner

less than one centimeter from the tube opening. The solu-

tion pipe of the aspirator burner was extended with a small

piece of tubing to allow aspiration in a horizontal posi-

tion.

The flow rate of aspirating gas was 2.25 1./min.

for argon and 2.75 1./min.' for air. The resultant solution

flow rate was then 1.0 ml./min. The flow rate of hydrogen

was optimized for each element and is given in Table 7.

The slit width used throughout this investigation

was 10 microns. This corresponds to a theoretical spectral
0
band width of 0.16 A in the first order. The spectral band

width, however, was measured by the method described in
0
the previous section, and was found to be 0.32 A.

Near the limit of detectability, a scale expansion

technique was used to increase the accuracy of measurement.

Scale expansion was accomplished by proper adjustment of

the zero suppress and by using a lower scale setting (i.e.,

12.5 mV. to 4.0, 2.5, or 1.25 mV.) on the recorder. The

phototube voltage used during the determination of each

element is given in Table 7.















Lr) Lr) LQ CY) LO
0 0 0 N 0 L
00000000000 10 1 O-'00 o
00000000-00 Oooo000


CYn CY) l r-I CY) %D V) i~
000o00n00' I
OOOOOO00 1oo 1
0000000000 o o -zO C,4


ooooo ooo oo in o oooe

00000000000000000000










00000000000000000000
OOOOO M0 00tt000f 0


























r0LC0 fr) 0 0-1 C4 r0 1 7-
oC oC '4C'J
O ~~~o~o~~o ~





0 o0~ ~ o~~oo ~


*Cr CT CI 00 a 0


Sc r o (r 0-
Tag I o o-4


U 3*0 a u C u a



C< 4 L r in D r-c oo
r-4 -4 r-4 r-4 r-4 r-I r4


0

0


00
0

0O
0
-U


4-a1
0C




5






-4














u LrC

3*


> cn


,-4 C


0 Ln C'4

- 00





























000












000
0N-0
r-4 --4





























1r)0CC
0 C) 0
















< 00 I'D














0co C: r








c;

pio i
CHH


4C4C'


-4



CM
0


0


> -4
-4 4-4
0
CU) C
V) :z
*rH

S



U)
4 4-)


) 4
04






0 0
)Q)








a f
) 4-C






( u4
X)
C) L



C) 4-l


0
C



O
O--


Ul






4 0
4J tU)
-4 4J

CO lO
U)





C)
a0 Q0

4-) 4-J
C
ol







-40 4
tU r

) a)






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CU )




0 0










,a -4
cU 4)
E a






4) 4)
d) 0






t0 a0


a-
So


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0
0


4)
co
Q 0
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u


o

-4 4

4J -



-4


4-J

00
Pc




U









4 4






E
0
SU
Ca 'ri
*^






00

cs
&>d ~
3^










Solutions

Stock solutions of 1000 ppm for each element were

prepared by dissolving the appropriate salt in aqueous, or

the metal in acidified-aqueous solution. More dilute

solutions were made by successive dilution of this stock

solution. In the case of the solutions prepared by dis-

solving the metal in acid, a small but constant concentra-

tion of acid was maintained in each dilution. The specific

salts used to prepare the stock solutions are given in Table

7.

Procedure

The wavelength used for the atomic absorption measure-

ments of each element is selected by aspirating a 50 ppm

solution of the element of interest and then manually scan-

ning to locate the wavelength of maximum absorption. Scan-

ning the wavelength range is useful for the following

reasons:

(1) The optimum wavelength for analysis can be

determined if more than one wavelength is available (e.g.,

the transition metals).

(2) The noise on the background signal adjacent to

the wavelength of interest can be measured.

(3) The presence of contaminating elements in solu-
tion which may interfere with the element under investigation

can be determined.










The flame tube is flushed after each measurement by

continuously aspirating water. This is necessary to extend

the lifetime of the flame tube by preventing burn out and

salt fusion, and to reduce the noise on the background

signal. Periodic flushing (between use in analysis) of the

tube with dilute HNO3 minimizes the decrease in reflectivity

of the flame tube due to salt fusion.

Additional discussion of the experimental technique

and problems encountered when using the flame tube may be

found in articles by Fuwa and Vallee (14), and Koirtyohann

and Feldman (24).


Results


Limits of detectability for twenty-one elements

measured using the experimental technique described above

are given in Table 7. The limit of detectability (45) is

defined as that solution concentration resulting in a

signal-to-noise ratio of 2.0. Noise is defined as peak-to-

peak divided by 2. The limits of detectability given in

Table 7 represent an average of nine determinations having

about a 50 per cent relative standard deviation. It should

be noted that the values given in Table 7 represent the

lowest obtainable using the experimental set-up described

in the apparatus section of this chapter, and various

combinations of fuel and oxidant. In each case for each










element, various combinations of C2H2, H2, 02, and air as

well as argon were tested to see which combination gave tho

lowest limits of detectability.

Relative standard deviations wore calculator orn the

basis of nine runs for 100 ppm and at a ton-fold concentra-

tion higher than that determined for the limit of detecta-

bility as well as at the limit of detectability. For

concentrations ten-fold higher than the limit of c-.o.-'cility,

the relative standard deviation was never larger than 1.0 per

cent for all elements run; whereas at 100 ppm, the relative

standard deviation was between 2.0 and 8.5 per cent, de-

pending on the particular element.' in Figure 7, typical

working curves for three elements are given. The data for

these three elemtns are treated in the conventional manner

(i.e., plots of absorbance vs. concentration) to illustrate

the similarities between the two types of absorbance working

curves (i.e., curves plotting relative absorption and

absorbance vs. concentration). As discussed in a previous

section (see Figure 4 for fraction of intensity vs. concen-

tration working curves for the same three elements), the

shapes of the working curves are characterized by a linear _

portion in the low concentration range which extends to

about a 10 per cent absorption. From Figure 7 for the flame

tube study, it can be seen that the working curve for silver

is linear from 0.01 ppm to about 100 ppm, whereas the copper








66

and sodium curves are linear from about 0.02 to about 30 ppm.

All other elements give curves similar to those of sodium

and copper.

Due to the extreme curvature of the working curves at

high concentrations, a working curve must be prepared prior

to performing quantitative measurements. Fassel and co-

workers (12) have described the signal corrections which

must be considered when preparing absorbance versus solution

concentration working curves. From a comparison of the two

types of working curves (see Figures 4 and 7), it should be

noted that when it is necessary to work with high solution

concentrations falling on the nonlinear portion of the

absorbance curve, the experimental procedure described in

the Introduction would be preferred because of the more

favorable slope (proportional to concentration) in this

region.


Discussion


To meet the requirements imposed upon the experimental

system, all components chosen for the analysis system are

characterized by a wide range of operating conditions in

order to meet the varying needs of the analyst.

A spectral continuum as a source of radiation

certainly eliminates many of the restrictions placed on

atomic absorption by the use of line sources of radiation.



























cd
rd




U

hD *
4 0

SU



,0
0


ko


c 0
O




0
0 8r





r-1





Od

C60
o*















































V30i^eOS@V









The added versatility of the qualitative aspect of atomic

absorption analyses eliminates this present inherent limita-

tion of the line source. In this study, a qualitative

investigation and quantitative estimate of the sensitivity

of the major atomic absorption lines of each element was

used to determine the absorption lines for measurement.

The total-consumption aspirator-burner was chosen

primarily because of the simplicity of sample introduction,

and because of the wide range of fuels and oxidants which

can be used with it. However, one major disadvantage of the

total-consumption aspirator-burner for atomic absorption

studies is the very short absorption path length of the

flame even under very fuel-rich conditions. This is a

serious handicap when sensitivity is desired. Several at-

tempts were made at finding a means for lengthening the path

length of the radiation through this flame. Multiple pass

of radiation from mirrors through the flame, multiple

burners (in line), and multiple pass of radiation through

multiple burners were just a few of the designs tried. How-

ever, it was found that the flame tube, when combined with

the argon/hydrogen-entrained air flame (Ar/H2-E.A.) gave

results superior to all other designs. The flame tube not

only extends the path length of the radiation through the

flame, but in addition, because of its cage effect (it

directs the flame in the radiation path and prevents outer









diffusion of atoms), it extends the residence time of atoms

in the light path.

Fuwa and Vallee (14) were the first to suggest the

use of the flame tube for atomic absorption analyses; how-

ever, they used line sources of radiation. Later

Koirtyohann and Feldman (24), and more recently, Koirtyohann

and Pickett (25,26,27) have determined limits of detectability

and discussed possible sources of spectral interference

using the flame tube. It is interesting to note that al-

though their application involved use of a line source of

radiation, a spectral continuum source was suggested as a

means of correcting for spectral interference.

The flame tube has the additional advantage that

misalignment of the aspirator-burner or incorrect position-

ing of the flame in the light path is not as critical as

alignment of the line source and acetylene-air flame used

with most chamber type aspirator-burners. Of course, align-

ment of the flame tube in the light path is critical.

The Ar/H2-E.A. flame was used in these studies be-

cause of the success of this flame in atomic fluorescence

(39) and atomic emission (46) studies. The total-consumption

aspirator-burner combined with the Ar/H2-E.A. flame is an

efficient method of producing atoms. This is evident from

data given in Table 7.










The good sensitivity of the Ar/H2-E.A. flame is a

result of two factors, namely: the Ar/H2-E.A. flame has

a very low background which results in greater sensitivity

(39,45); and the total-consumption aspirator-burner in con-

junction with the Ar/H2-E.A. flame and the flame tube

results in greater efficiency of atomization than is ob-

tained for most other aspirator-burner-flame systems. The

longer residence time of atoms in the flame tube and the

reducing characteristics of the flame gases decrease compound

formation, and,therefore, increase efficiency of atomization.

The requirements of the monochromator when using a

spectral continuum of radiation are, of course, more criti-

cal than when using a line source of radiation. For the

case where the line source is used, Walsh (41) concluded

that because the decrease in the peak intensity of the line

was measured, only a low resolution monochromator capable

of isolating the spectral line from the source was required.

For the case where the spectral continuum is used, Winefordner

(42) has shown that as the spectral band width of the mono-

chromator approaches the absorption line width of the atoms

in the flame, the sensitivity of measurement will increase

almost linearly with decrease in the spectral band width.

This effect undoubtedly accounts in part for the increase

in sensitivity found for elements in this study. These re-

sults confirm the statement by Gibson, Grossman, and Cooke










(16) that a medium resolution, large aperture bench-sized

monochromator combined with a scale expansion technique

should give good sensitivity; the monochromator used in

their study and in this one were identical.

One additional comment about the monochromator. If

the analyst wishes to analyze for elements which have widely
O
varying resonance wavelengths (e.g., cesium at 8500 A and

zinc at 2100 A), some of the difficulties encountered with

the transmission range of the monochromator can be overcome

by choosing a grating with a long wavelength blaze (e.g.,
O
7500 A in first order). In the lower wavelength region

where intensity in the first order is low (for a 7500 A

blazed grating), higher orders of the radiation can be used

satisfactorily.

In conclusion, using the experimental system previ-

ously described, the limits of detectability are comparable

to or greater than the best values listed in the literature

for a line source, acetylene-air, chamber-type flame system

and the values listed by Fassel and co-workers (12) for the

continuous source, fuel-rich acetylene-oxygen, total-

consumption system (see Table 7). This certainly indicates

that the spectral continuum (in conjunction with the flame

tube and the Ar/H2-E.A. flame system) as a source of excita-

tion should be competitive to the use of the line source and

a typical air-acetylene flame and chamber-type aspirator-







75

burner measurements in addition to providing added versa-

tility to the system, which the analyst can always use.












FUTURE WORK


The work presented in this dissertation demonstrates

the feasibility of using a continuous source in atomic

absorption flame analyses. However, during this investi-

gation, other areas for research became apparent, primarily

as a result of the interpretation of data concerr-n, ve

measured a parameters. Research is definitely needed to:

(1) Establish the reasons for the wide divergence

in atom formation efficiency factors found for chamber and

total consumption-type burners; an approach utilizing the

measurement of absolute emission intensity and total ab-

sorption for elements atomized in both types of burners

could be used to determine the absolute atom concentration.

(2) Establish the relationship between the spectral

band width required to produce a satisfactory curve of

growth and the half-intensity width of the line under

investigation; as the first step, an instrument of high

resolving power (interferometer) could be used to establish

the profiles of the lines produced in this type of flame

(see Appendix I).

(3) Determine the nature of the perturbing species
in the flame produced from a total consumption-type burner;

the effect of the large quantity of water introduced into

this flame should be established.'







75

The absorption technique used in this study should

be used to determine fundamental atom parameters (such as

those investigated in this study) in flames of low burning

velocity from a chamber-type burner. These values will be

compared with those previously determined by one of the

emission techniques.













CONCLUSIONS


The major contributions made in this dissortation

are:

(1) Application of theoretical relationships derived

in astrophysics to atomic absorption measurements ''th a

continuous source.

(2) Derivation of a relationship between fraction of

radiation absorbed cq, and absorber concentration and useful-

ness of this relationship for preparation of experimental

working curves over wide ranges of absorber concentration

(working curves are useful over a wide concentration range

and any interference can be readily detected by a change

in the characteristic shape of such a working curve).

(3) Measurement of spectral parameters such as

damping constants and collisional cross-sections of lines

of atoms in flames of high burning velocity.

(4) Demonstration of the usefulness of the continuous

source and a Ar/H2-E.A. flame in a quartz tube for the de-

tection of low concentrations of a number of elements by

atomic absorption flame spectrometry.

The advantages of using a continuous source and a

Ar/H2-E.A. flame are;










(1) The low limits of detection obtained are

comparable with similar values obtained using line sources.

(2) The use of one experimental system for the

qualitative and quantitative determination of a large

number of elements in a variety of sample matrices.

The only serious disadvantage of such a system is

that an intense continuum and a medium resolution rather

than a low resolution monochrcmator must be usc. hv;-

ever, such a system is still considerably cheaper and more

versatile than an atomic absorption spectrometer using line

sources.












APPENDIX I


If the spectral band width, s, is of the same order

of magnitude as the absorption line half-iZ-tezsity wdlth

of atoms in the flame gases, for example, as for alkali

atoms at high atom concentrations in flames, then the

measured value of ca, will not be the same as Aj/s as de-

fined by equation 12. A correction factor relating the

measured ac to AT/s can be determined by assuming a certain

slit function distribution, for example, if a triangular

slit function g. is assumed then


c (23)


aid if the above expression is evaluated, then


A C (I + -), (24)
T S S

where the term in parenthesis is a correction factor to

convert the measured value of ac to the defined value of ac

(equation 12). As can be noted for the above case, little

error results as long as the measured values of ac are less

than 0.l.' However, for the alkali metals, ac is greater

than O.1 unless slit widths greater than 200 microns are

used,












LITERATURE CITED


1. Behmenburg, W., J.g.S.R.T. 4, i77 (1964).

2. Behmenburg, W., Kohn, H., J.~.S.R.2. 4. 1~ (19., ).

3. Bockris, J. 0'M., White, J. L., MacKenzie, J. D.,
"Physiochemical Measurements at High Temperatures,"
Butterworths, London, 1959.

4. Broida, H. P., Lalos, G. T., J. Chem. Phos. 20, 1466
(1952).
5. Corliss, C. H., Bozman, W. R,, "Experimental Trransition
Probabilities for Spectral Lines of Seventy Elements,"
N.B.S. Monograph No. 53, Washington, D.C., 1962.

6. Crosswhite, H. M., "The Spectrum of Iron I," John
Hopkins Spectroscopic Rept. No. 13, August, 1958.

7. de Galan, L., Personal Communication.
8. de Galan L. Winefordner, J. D., Anal. Chem., in
press, 1966.

9. de Galan, L., Winefordner, J. D., Submitted 1966.
10. de Vos, J. C., Physica 20, 690 (1954).
11. Fassel, V. A., Mossotti, V. G., Anal. Chem. 35, 252
(1963).
12. Fassel, V. A., Mossotti, V. G., Grossman, W. E. L.,
Kniseley, R. A., Soectrochim. Acta. 22, 347 (1966).
13. Fery, Ch., Comptes Renders 137, 909 (1903).

14. Fuwa, K., Vallee, B. L., Anal. Chem. 35, 942 (1963).

15. Gaydon, A. G., Wolfhard, H. G., "Flames, Their Struc-
ture, Radiation and Temperature," Chapman and Hall
Ltd., London, 1960.









16. Gibson, J. H., Grossman, W. E. L., Cooke, W. D.
"Analytical Chemistry" (proc. Feigl Anniv Sym.) pg. 296,
Elsevier, 1962.

17. Hermann, R., Alkemade, C. Th. J. "Chemical Analysis
by Flame Photometry" (trar.liatdi by,, T. G-lbert),
John Wiley and Sons, New York, 1965.
18.' Hinnov, E., J. O0t, Soc. Am. 47, 151 (1957).

19. Hinnov, E., Kohn, H., J. Opt. Soc. Am. 47, 156 (1957).

20. Hoffman, F. W., Kohn, J., J. Opt. Soc. Am. 51, 512
(1961).
21. Hollander, Tj., Thesis, Utrecht (1964).

22. Ivanov, N. P., Kozireva, N. A., Zh. Analit. Ki. 19,
1178 (1964).

23. Jones, H. C., Fisher, J. D3., Kelley, K. T., "Fifth Con-
ference on Analytical Chemistry in Nuclear Reactor
Technology," Gatlinburg, Tennessee, October, 1961.
T.I.D. 7629.

24. Koirtyohann, S. R., Feldman, C. "Developments in
Applied Spectroscopy," Vol. 3, J. E. Forrette ed.
Plenum Press, New York, 1964.

25. Koirtyohann, S. R., Pickett, E. E., Anal. Chem. 37,
601 (1965).

26. Koirtyohann, S. R., Pickett, E. E., Anal. Chem. 38,
585 (1966).
27. Koirtyohann, S. R., Pickett, E. E., Anal. Chem. -38,
1087 (1966).

28. Ladenburg, R., Reiche, P., Ann. d. Phys. 42, 181 (1913).

29. Minkowski, R., Z. f. Phys. 36, 839 (1926).

30. Mitchell, A. C. G., Zemanski, M. V., "Resonance Radi-
ation and Excited Atoms," Cambridge University Press,
London, 1961.

31. Parsons, M. L., Winefordner, J. D., Appl. Spect. in
press, 1966.

32. Parsons, M. L., McCarthy, W. J., Winefordner, J. D.,
Anal. Chem. in press, 1966.







81

33. Penner, S. S., "Quantitative Molecular Spectroscopy
and Gas Emissivities," Addison-Wesley, Reading, Mass.,
1959.
34. Rubeska, I., SvobodaV., Anal. Chi-n. Acta 32, 253 (1965).

35. Slavin, W.,.Atomic Absorption Newsletter, No. 24,
Sept., 1964.

36. Unsold, A., "Physic der Sternatmosphoren," Springcr,
Berlin, 1955.

37. van der Held E F. M., Ornstein, S., Z. f. Phys.
77, 459 (193 ).

38. van Trigt, C., Hollander, Tj., Alkemade, C. Th. J.,
J..S.R.T. 5, 813 (1965).
39. Veillon, C., Mansfield, J. M., Parsons, M. L.
Winefordner, J. D., Anal. Chem. 38, 204 (1966).
40. Vickers, T. J., Remington, L. D., Winefordner, J. D.,
Anal. Chim. Acta in press, 1966.
41. Walsh, A., Spectrochim. Acta. 7, 108 (1955).
42. Winefordner, J. D., Aopl. Soect. 17, 109 (1963).
4r. Wineforiner, J. D., Mansfield, C. T., Vickers, T. J.,
Anal. Chem. 35, 67 (1963).

44. Winefordner, J. D., Vickers, T. J., Anal. Chem. 36,
1959 (1964).
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(1964).
46.' Zacha, K., Winefordner, J. D., Anal. Chem. in press,
1966.

47. Zaer, R. A., Thesis, Paris (1935).












BIOGRAPHICAL S NETCH


William Walter McGee III was born June 27, 1939,

in Toledo, Ohio. In June, 1957, he was graduated from

Jesup W. Scott High School, Toledo, Ohio. In June, 1961, he

received the degree of Bachelor of Science from the Uni-

versity of Toledo, Toledo, Ohio. In June, 1962, he received

the degree of Master of Science from the University of

Toledo, Toledo, Ohio. From September, 1963, until the

present time, he has pursued his studies toward the degree

of Doctor of Philosophy.

He is married to the former Mary Ann Nietz of

Toledo, Ohio.
















!










This dissertation was prepared under the direction

of the chairman of the candidate's supervisory committee

and has been approved by all members of that committee. It

was submitted to the Dean of the College of Arts and Sciences

and to the Graduate Council, and was approved as partial

fulfillment of the requirements for the degree of Doctor of

Philosophy.


December 17, 1966 /


Dean, Col ge,/of Arts and Sciences



Dean, Graduate School
Supervisory Committee:


C airman






_^iA_C_;d157ri




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