IR SPECTROSCOPY TO TOILET ARTICLES AND HOUSEHOLD PRODUCTS 15 samples were shredded and their moisture contents determined by Dean and Starke distillation with 95/120 ø petroleum ether. Simultaneously, the ATR spectrum of each sample was recorded in triplicate, at an angle of 33 ø, and the ratio of "absorbances" calculated using a tangent base-line drawn between 2500 and 4000 cm -x. In Table IV are recorded the results obtained for several samples of soap. These moisture contents are com- pared with those obtained by loss in weight, at reduced pressure, under an IR heater. By the latter method the results are in fact the percentage volatiles but for these samples they closely approximate to the moisture content. Table IV Moisture content of soap samples, (a) by ATR method (b) by loss in weight at reduced )ressure under an IR heater. % w/w moisture Sample no. (a) (b) 12.4 12.9 13.0 12.5 14.3 13.9 12.8 12.9 12.9 13.2 14.0 14.0 14.0 14.2 13.6 13.7 13.4 13.5 13.5 9.6 9.5 9.7 9.6 14.3 13.8 13.4 13.7 13.7 13.5 9.3 9.7 9.7 9.5 It was found that for the ATR method the standard deviation was 4-0.25% at the 13.0% w/w moisture level. The examples quoted above show the type of components in various products that can be determined directly by the ATR method. It should be pointed out that the component, or components, determined were relatively major ones, being at least 5% w/w concentration. A further point is that these analyses, which required less than 8 min per deter- mination, could be used for the routine control of such products with

16 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS the added advantage that a permanent record of the analysis is also obtained. (Received: 16th September 1965) REFERENCES (1) Puttham, N. A., Lee, S. and Baxter, B. H.J. Soc. Cosmetic Chemists 1õ 607 (1065). (2) Fahrenfort, J. Xth Colloquium Spectroscopicum Internationale, Maryland, 1062. ($) Fahrenfort, J. Spectrochim. Acta 17 608 (1061). (4) Wilhite, 1•. N. and Ellis, R. F. Appl. Spectry. 17 168 (1065). (5) Katlafsky, B. and Keller, R. E. Anal. Chem. 8õ 1665 (1065).