acids (12), and solanesol-like substances (1) in tobacco have been 
developed, and the levels in various tobacco types and grades have been 
reported. 
The values for total aliphatic paraffins in this previous analytical 
(0.23 percent) and the present compositional (0.24 percent) studies are 
similar. However, a valid comparison may be questionable here, since 
the response of the cycloparaffins, which were found subsequent to the 
development of the analytical method, is unknown. Based on available 
evidence, their response, if any, would appear negligible, and the 
analytical method measures aliphatic paraffins. 
A comparison of the sterol levels is more difficult, since only an 
approximation of the total steryl esters of fatty acids in the n-hexane 
extractives can be made (11). Based on such approximation, the total 
(free, esterified and glycosidated) sterol level in the compositional studies 
is less than 0.2 percent compared to the analytical value of 0.43 percent 
(7). Several possible reasons for this difference are apparent, including 
failure to isolate all sterols in the extracts, such as those present ina 
small fraction of the n-hexane extract (see footnote 2, table 4), or 
incomplete extraction, or both. Although the overall large-scale 
extraction was rather thorough (2), sterols are difficult to remove from 
tobacco and the extraction may have been incomplete for these components. 
A similar situation exists with solanesol. Although the analytical 
procedure (1) determines solanesol-like substances (SLS), the bulk of the 
material responding to the method is probably solanesol. The analytical 
value for this tobacco was 1.32 percent, which was about 30 times higher 
than the level in the compositional work, assuming 70 percent of SLS is 
solanesol (1). Some of this difference may be due to incomplete extraction 
or to the difficulties of isolating solanesol. Because solanesol is eluted 
very slowly from silicic acid columns, it is distributed through. many 
fractions, withprobable overall loss through dilution with other components. 
The values for free higher fatty acids in the analytical study (12) 
(0.39 percent, moisture-free basis) and in the composition study are very 
similar. 
Although many water-insoluble components of the hexane and ethanol 
extractives have been isolated and identified, most of the substances remain 
unidentified. Much additional work is required to fractionate the compo- 
nents in the ethanol extract and to determine their role, if any, in the 
many practical problems of tobacco utilization. 
10 
