- 46 - 
HesTilts by this method were said to "be in agreement with those "by the various 
published proced-ores, including the official' A." 0. A; C, method. 
L'isouBsioo ' 
It is generally agreed that derris and cube root should be finely 
grovmd and air-dried before extraction. Several investigators (71, 87^) 
have shown that drying at elevated temperature is detrimental to the 
determination of rotenone. ' ~ - 
One of the best solvents for extracting rotenone for analytical 
.purposes is chloroform. Extraction at room temperature seems to be pre- 
ferred by most workers. This method is rapid, yet it extracts less extra- 
neous material and involves less decomposition than the use of other sol- 
vents or higher temperatures. For most roots the aliquot procedure appears 
to be entirely suitable, but for roots with a high proportion of rotenone, 
as pointed out by Jones and Graham (71) and I^IeiJer and Koolhaas (89_), a 
more exhaustive extraction must be resorted to. For this reason the alter- 
native multiple-extraction proced.ure is included in the official A, 0. A. C. 
method (2).^' 
Crystallization from c.arbon tetrachloride as carried out by most of 
the present methoc-s may be consi-iiered to be reasonably complete. It is 
possible, as indicated by the work of Cahn, Phipers, and Boam (17.), and 
of l.'ei.jer and Koolhaas (89) , that in some few samples, particularly those 
with a very low ratio of rotenone to total extract, a small proportion of 
the rotenone r^^.T.ains unaccounted for in the mother liquor. 'rt"hile the 
reviewer (66) believes this to be primarily a result of greatly retarded 
rate of crystallization in certain types of extracts, other investigators 
(17) state that it is due to an actual solvent effect of other constituents. 
Whichever may be the case, anything that can be done to increase the 
relative proportion of rotenone v/ill aid in producing more nearly complete 
crystallization in the time allowed. The addition of pure rotenone (13, 
65), the treatment with decolorizing carbon ( 130 , 46) , and the removal 
of alkali-soluble material (64) all tend to accomplish this result. 
In the reviewer' s opinion, when these schemes or combinations of them 
are employed, samples in whicn rotenone remains unaccounted for in the 
resin will be encountered, only rarely, and even then results will not be 
greatly in error. If derris samples with a very low proportion of rotenone 
to total extract are to be encountered regula'rly on the market, alkali 
extraction may become a necessary step. Such roots as these usually 
contain a large proportion of toxicarol and other phenols, and their 
removal undoubtedly improves the crystallization of the rotenone. 
8 Recently a sample of derris root encountered in the laboratories of this 
Bureau was not completely extracted even by this method and it was neces- 
sary to resort to hot extraction. This sample contained about 10 percent 
of rotenone and 24 percent of total extract. 
