- 40 - 
The method of Sell gave results conridt=!ra'bly lower than by the other 
methods. However, another sar.plo prepared "by the Butch laboratory and 
analyzed "by Sell, Putt, and Rushy £:ave slightly higher results by the Sell 
method than "by the Jones and Grah-im method. Although Braak "believed the 
method of Koolhaas to ^ive figures closer to the actual rotenone content, 
he stated that it would "be most desira"ble for the method of Jones and Graham 
to "be applied universally, since it satisfied all reasona'ble demands for 
reproducibility in various laboratories and the chance of its general accept- 
ance seemed better than for any other method. 
Begue (5) in 1939 stated that the technique of Worsley was one of the 
best gravimetric procedures for rotenone determination, and he advised its 
use for derris root. 
Kumerous methods for evalijatin;- rotenone-bearing plants were criti- 
cally reviewed by Guillaujne and Ke'rve (53) in 1939. All crystallization 
methods were said to be impractical for determining small quantities of 
rotenone, as crystallization is not effected. Increasing the size of the 
sajuple was said to diminish th? sensitivity of the method. Such methods 
were said to be inapplicable to leaves end fruits. Colorimetric methods 
or a determination of inethoxyl groups v;as recommended. 
Georgi ^& Teik (5?) in 1939 stated that the findings of Seaber ( ill ) 
on decomposition of rotenone. after prolonged boiling with carbon tetra* 
chbrid^ had been confirmed in fneir laboratory. Consequently they had dis- 
continued the use of this solvent and substituted room-temperature extrac- 
tion wifi chloroform. Sxtraction and cr^'stallization were carried on as in 
the methods of Beach (3) anc^ Jones and Graham (72), except that the extract 
was allowed to crystalline for 2 days. One gram of pure rotenone was added 
to extracts of roots containing 6 percent or less of rotenone. After sepa- 
ration of the first crop of crude carbon tetrachloride solvate, the volume 
of the mother liquor was reduced to 15 cc. and placed in the refrigerator 
fpr 1 day to obtain a second crop of crystals. They were added to the 
first crop and the purity of the whole was determined by the alcohol- 
recovery method of Cahn and Bosun (13). 
Graham (49) in his 1939 report to the Association of Official Agri- 
cultural Chemists, described the results of collaborative analyses of five 
samples of derris, timbo, and barbasco by the crystallization method (72) 
and by the titration method (§7). Decolorizing carbon was used in the 
extraction flask as a result of the findings of Graham (46) on this point. 
Results were in fairly close agreement except on one sample of derris root 
of low rotenone content, which gave poor results by both methods. It was 
recommended that the cr>-stallization method, adopted as "tentative" in 
1937, be amended to include the use of decolorizing carbon and be adopted 
as "official, first action." 
Graham (48) in 1940 reviewed the results cf the collaborative analyses 
just described. He pointed out that the addition of decolorizing carbon re- 
sulted in higher values for cube samples, and stressed the necessity of 
using the multiple-extraction procedure with chloroform for sajcples with a 
ratio of rotenone to total extract greater than 40 percent. 
