- 15 - 
Subsequent early investigators (Nagai (90), Ishik^wa (60) , and 
Takei ( 117 )) f^enerally emplb7'-ed ether for the separation of rotenone. 
Tattersfield and Hcach (122) used alcohol.. The sanie authors quote iJurnam 
as statins that the "best method, of obtaining pure rotenone was extraction 
with petroleuTi ether followed by recrystallization from alconol, the 
iTiethod employed earlier by Geoffroy. 
Hoarl: ( lOO ) in 19?0 was the first to propose a quantitative method 
for determining rotenone. This m'^^thod, based on tae separation used at 
that time in the United States Department of Agriculture, consisted 
essentially in extracting 100 grains of root with ether and crystallizing 
tne rotenone from the extract concentrated to 25 cc. The filtered 
crystals were washed with ether, dried, and weighed. 
Browii and Skinner (10), as editors of Wiley's Principles and Prac- 
tice of AgricultTira.l Analysis, quoted- Ptoark' s method. I'or the determina- 
tion of rotenone in commercial derris preparations they suggested extrac- 
tion with ether and precipitation of the rotenone, along witn some resin, 
from tne concentrated extract b-> tie addition of petroleum ether. 
Spoon ( 115 ) , in the determination of rotenone in 12 samples of 
derris root, utilized cr.^ stallization from ether by Hoark' s method. 
In 1931 Jones (61) suggested the use of carbon tetrachloride to 
replace ether in the analytical extraction of rotenone from derris and 
cube roots. '3ther often gave extracts from waich it was difficult to 
separate rotenone. Carbon tetrachloride e:< tracts gave a quicker and more 
selective separation of the rotenone. In several cases in which no 
rotenone could be separated from the ether extract, carbon tetracnloride 
extracts separated rotenone readily. The rotenone separated from solu- 
tions in carbon tetrflchloride as a. solvate containing 1 mole of the sol- 
vent to 1 mole of rotenone. 
Blackie (7) in 1932 described an apparatus with groundglass .joints 
and mercurj'- sealjs, which was especially designed for the determination 
of the rotenone content of a Fijian plant b:'' extraction, wita ether. In 
the same vear Elackie (&) published results obtained for the rotenone con- 
tent of Derris uliginosa -ising tais apparatus and extracting for 36 .lours 
with ether. 
Georgi and Teik (33) in 193? described a r.iodif ication of P-oark's 
ether extraction method. They dried a 100-g^. sample in a water- jacketed 
vacuum drying oven at approximately 75° C. and then extracted with ether. 
The extract was concentrated to 40 cc. and crystallized in the cold cabinet 
overnight. 
In the sa-ne. year x-ool.haas (78) discussed the methods for the esti- 
mation of rotenone then in use. Tne ether extraction methods in particular 
were said tc be subject to error from such sources as insufficient fine- 
ness of root, too large a sample so that on evaporation of the extract the 
other substances present exerted an appreciable solvent effect, difficulty 
in wasning the rotenone free of impurities, and difficulties encountered 
in the filtration of viscous ether solutions. He proposed an ether extrac- 
tion method for derris root designed to overcome these objections. 
