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In 1940.1''e.i.jer arid I^oolhaas (69_) r'sscri'bed the method in use at 
the Laboratory for Chemical Research, Buitenzorg, Java, for determining 
rotenone in derris root. This is a modification of the original method of 
Koolhaas (78), and. since it is one of the more important methods now in use 
it is presented in some detail here: 
"Extraction. ?ifty gr.ams of powder (at least 75 percent 
must pass an 80 mesh sieve) are percolated with ether in a 
Soxhlet , without a thimble but with cotton wool at the bottom, 
for 65 hours. The heat used for boiling the ether comes from 
a SO-watt electric bulb. 
'Tistillinj- off the Solvent. The ether is distilled off 
in a 100 cc. centrifuge tube on a water bath; the tuba is 
filled with the ether solution by means of a dropping funnel. 
Th9 rotenone which may have seps.rated during the extraction is 
transferred quantitatively to the tube, and the flask is rinsed, 
out with ether a few times. The final solution in the tube 
must be 25 cc. The tube is then tightly closed with a cork. 
"Crystallization of Rotenone. The tube with the ether 
extract is kept at room temperature for 1 day axxA then in a 
refrigerator for 2 days. The mother liquor is poured into a 
50 cc. Hlrlenmeyer flask and the remaining crude rotenone is broken 
up with a spatula, with the addition of 10 to 15 cc . of ether. 
The tube and the ^rlenmeyer flask are closed with a cork and 
placed in the refrigerator for another day. 
"Determination of Rotenone. The rotenone is centrifuged 
for 3 to 5 minutes at 3500 revolutions per luinute and the 
supernatant liquor is added to the mother liquor in the 
3rlenmeyer flask. Tine centrifuge tube with the crude rotenone 
is dried for 10 minutes in a water bath at 70° C., and after 
a slow current of air has been passed into the tube, it is 
dried in vacuo on a boiling water bath for 15 minutes. After 
cooling in a desiccator the tube is weighed. ♦ * * The purity of the 
crude rotenone is determined by the melting point, using an 
empirical table in which the correlation between the purity 
and melting point is given. If the melting point is lower 
than 140*^ C , the mass in, 'the centrifuge tube is treated with 
another 10 cc . of .ether, centrifuged, and dried, and the 
melting point is again determined * * *.■ The autnors determine tho 
optical rotation, from which the purity of rotenone can, also 
be determined. A correction is made for the amount of rotenone 
dissolved in the ether of " .the mother liq\i.or and the ether used 
for washing. For each cubic centimeter of ether used 4.2 mg. 
of rotenone are added to the amount of pure rotenone. If loten- 
ona has separated from thei^other liquor to which the wash ether 
has been added, after standing in the refrigerator for another 
night, it is centrifuged off and added to the crude rotenone * * ». 
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