- 27 - 
Various methods of extraction wera used, but in all except tv/o of the 
laboratories the rotenone v/as separated as the carbon tetrachloride solvate. 
Laboratory A used both Soxtilet extiaction and maceration with refluxin^; 
the latter method, using benzene, was preferred; the crude solvate was 
p-orified by an alcohol-recovery test. In laboratory B the sample was mixed 
with ssjid and extracted with carbon tetrachloride for tv/o 6-hour periods; 
an alcohol-recovery test was included. The method used by laboratory C 
involved maceration v/ith chloroform for two extended periods; no test of 
the purity of the solvate was made. Laboratory I> made comparative Soxhl,-«t 
extractions with trichloroethylene , chloroform, ana ether; ether extrac- 
tion gave markedly lov;er values, and the first metnod. v/as preferred; alcohol 
recovery v/as used for purification. Sther extraction of the sampl? mixed 
with sand in a Soxhlet for 24 hours v/as used by laboratory 3; the usual 
alcohol-recovery test was employed. Laboratory F extracted the sample for 
6 hours in a Soxhlet with carbon tetrachloride and used no final purifica- 
tion. In laboratory G an extraction method usin.ff chloroform in a Soxhlet 
was compared with the optic^^l rotation of a benzene extract of the sample; 
both methods gave results much higher thajn these obtained by other labora- 
tories. Ether extraction in a Soxhlet for 6 hours, followed by crystal- 
lization directly from tne ether, with no purity tests, was the method 
used by laboratory H. The Isiboratory of the authors of the report (labora- 
tory I) used Soxhlet extraction witn ether for 48 hours, followed by 
crystallization from the ether and measurement of the purity 'bj determi- 
nation of the melting point. 
Koolhaas and !!eijer criticized the results on the basis that many 
of the laboratories did not obtain complete extraction of the root. Ben- 
zene, chloroform, and ether, the last-named as used in their laboratory (I), 
were stated to be suitable extraction solvents, but longer extraction than 
was used by i/;ost of the laboratories was said to be necessary. Use of melt- 
ing-point deteridnation in .judging the purity of the separated rotenone 
gave higher values thaja alcohol recovery, and these p.uthors preferred this 
method. They also pointed out that the optical rotation of the whole 
extract is of no value in d.etermining the rotenone content. They recom- 
mended that for analysis derris root should be ground so that at least 75 
percent passes an 60-mesh sieve, and that the moisture content sho\ild not 
be over 12 percent. 
Georgi and Teik (?6) in 1937 stated that rotenone may be lost at 
two stages of its determination. Tiras , some may not crystallize from the 
carbon tetrachloride but may remain in the mother liquor, while some may 
pass into solution when the co/nplex is trittirated with alcohol. i3eterjnina- 
tions of the optical rotations of alcoholic filtrates after recovery of 
rotenone indicated that the loss in triturating the complex witn alcohol 
amounted to approximately 6 percent, calculated on the weight of rotenone 
recovered. It vras not found possible to devise a method for estimating 
the a-Tiount in the carbon tetrachloride mother liquor, but the low optical 
rotation of the residual bodies in this liquor pointed to a smaller degree 
of retention than with the alcohol liquor. Tae total loss was estimated 
as possibly 10 percent. 
