A dual-purpose extraction rack


Material Information

A dual-purpose extraction rack
Physical Description:
Mann, H. D
United States -- Bureau of Entomology and Plant Quarantine
U.S. Department of Agriculture, Bureau of Entomology and Plant Quarantine (Washington, D.C )
Publication Date:

Record Information

Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030360812
oclc - 783192876
System ID:

Full Text

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United States Department of Agriculture
Agricultural Research Administration
Bureau of Entomology and Plant Quarantine


By H. D. Mann
Division of Insecticide Investigations

In connection with the determination of DDT in milk and fats by the
colorimetric method of Schechter et al. (1, 2), it has been necessary to
make extractions of fats and of nitrated DID on large numbers of samples.
To facilitate handling the separatory funnels required in these extrac-
tions, a convenient yet compact rack has been designed and constructed,
as shown in figures 1 to 3. The materials used- boards, stormwindow
braces, and spring-type night latches with chains- can be purchased at
almost any lumber yard.

The part of the rack used in the separation of DIDT from milk and
fats holds two banks (A, C) of eight 500-ml. separatory funnels arranged
in tiers. The tips of the funnels in the upper bank (A) are kept direct-
ly over the necks of the funnels below by a boari (B) fastened to the
uprights and notched to fit the upper funnels just above the stopcocks.
On the lower bank (C) removable blocks (E) 1 1/2 inches thick are placed
under the funnels to keep them close to the upper funnels during the sul-
furic acid extractions, as shown in the first three sets of funnels from
left to right in figure 2. After these extractions are completed the
chloroform solutions are combined in the upper funnels. The lower funnels
are cleaned with warm water, the blocks (Z) are removed, and the chloro-
form solutions are filtered into the lower funnels through plugs of
cotton held in glass Gooch crucible holders, which rest in the necks of
the lower funnels, as shown in the fourth and fifth sets of funnels in
figure 2. Here the chloroform solutions are washed with sodium bicar-
bonate solution and again filtered through plugs of cotton into 500-m1.
Erlenmeyer flasks with standard taper 2i4 40 joints, as shown in the last
three sets of funnels in figure 2. The details of the above procedure
are described by Schechter et al. (1).

The part of the rack used for the extraction of nitrated DDT holds
a single bank (D, D') of eight 125-ml. separatory funnels. It is con-
structed to use the same uprights as the first part in order to save
space. At each end of the rack two storm-window braces (G, G') are
fastened to the uprights below the bank (0) and to the board-(D, D').
This board swings on the storm-window braces and can be pushed back out of

I/The author is indebted to Mrs. A. C. Hazen for the drawings and to
R. A. Fulton and E. L. Gooden for the pictures.

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the way when not in use or pulled out in front when ready for use. Re-
versed bolts in spring-type night latches (F) fastened at each end of the
board (D, DI) in the back serve to hold it in the proper position. The
springs on the bolts push them into holes drilled at the required height
in the uprights. The two latches (_) are connected by a chain so that
both bolts may be unlatched with one band.

Since the size and shape of different makes of separatory funnels
vary, it is suggested that all the separatory funnels be bought from the
same company and the rack made to fit the funnels.

Literature Cited

(1) Schechter, M. S., Pogorelskin, M. A., and Haller, H. L.
1947. Colorimetric determination of DDT in milk and fatty materials.
Analyt. Chem. 19: 51-53.

(2) Soloway, S. B., Hayes, R. A., and Haller, H. L.
1945. Colorimetric determination of DDT. Color test for related
compounds. Indus. Engin. Chem., Analyt. Ed. 17t 704-9.

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48" (inside dimension)-
Partial front view of rack End view of rack

Figure I.- Diagram of dual-purpose extraction rock



Top view of tiers


Figure 2.--Use of the racic for separation of DDT from milk and fatty materials.

Figure 3.-Use of the rack for extraction of nitrated DDT with the bank (D,D')
of eight 125-inl. separatory funnels pulled out in front ready for use.


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