229 



CITRAL AND ITS ANALYSIS IN TERPENELESS EXTRACT OF 



LEMON. 



By SAMUEL H. BAER. 



The analyses were made by three chemists, including the writer, and as all three 

 judged the colon, it would seem that the analyses are as accurate as the colorimetric 

 method permits. Acknowledgment is due S. E. Shaffner for assistance rendered. 



I>> termination of citral in lemon c.rtnu-1 hi/ the rnlnri metric method. 



m these analyses it is seen that \\li.-u the colorimetric method is applied t<> the 

 < ts of commerce, the correct result i- nt trained. On sample N . I :;. a . -nr.il 

 solution, the analysis was reasonably close; samples No. 10 and 1 1 ate ter[>en<>lc*4 oils 

 of lemon and the low results on citral may be due to the fact that the sample pun 1 

 was not pure terpeneless oil of lemon, hut a product containing only 50 per cent <>i 

 the citral that should be tl 



Most iif the extraet manufacturers use 188 proof alcohol, that is, 94 per cent alcohol, 

 which always contains a certain amount of aldehydes, and the sample used in this 

 test, treating the alcohol the same a* the lemon extract, showed 0.1! per rent of < itral, 

 when there was no citral there at all. If only cologne spirits are used, the results 

 obtained are not so far wrong as if 94 per cent alcohol is used. 



Since, then-tore, the presence of the impurities in alcohol throw the results off to 

 such an extent. _ri\ ing too high a per cent of citral, would it not be possible that the 

 impurities in tin- alcohol at certain times and also in the water, and the very change 

 of one or two ingredients in the lemon oil, might make the result inaccurate, rev* 

 the analysis and showing a smaller per cent of (itral than is really present? 



The colorimetric method is applicable if the manufacturer used chemically pure 

 citral, distilled water, and aldehyde-free alcohol in the manufacture of his extracts, 

 l>ut such ideal conditions never exist. Further, any manufacturer could discreetly 

 add another aldehyde, even acetaldehyde, to the extent of 0.2 per cent, which would 

 give all the reactions of citral in the extract of lemon by the colorimetric method. 



The method is not without use, but if the presence of citral could be determined 

 and estimated quantitatively by a sodium sulphite or carbazone method, then the 

 colorimetric method might be used as a check. Before adopting the colorimetric 

 method as official a committee should be appointed from the association members to 

 test it carefully, under the conditions that the manufacturer must meet since he can 

 not use aldehyde-free alcohol, nor is he always in a position to use distilled water. 



