ANALYSIS OF SHAMPOOS 891 From the foregoing, one might conclude that there is no single univer- sal method which can be used to analyze all kinds of shampoos. A more rewarding approach, in our opinion, would be to use a combination of extraction and column chromatographic techniques to separate the in- gredients, without changing their chemical properties, and identifying the separated ingredients with some physical or chemical methods. Infrared spectroscopy appears to be the quickest tool for identification in most of the cases. PROPOSED METHOD OF SHAMPOO ANALYSIS The suggested procedure given below is one approach which might be taken to determine the composition of a shampoo: General Information by Examination of the Infrared Spectra of Solids A thin film of a partially dried sample (previously heated in a vacuum oven at 70 øC for 4 hours) is deposited on a (disposable) silver chloride optical window and the ir spectrum is recorded. Then, the ir spectrum of a water-free sample deposited as a thin film on a salt plate is recorded. Figure 2 is a representative spectrum of the water-free nonvolatiles from a commercial shampoo. The presence of polyols and many types of sur- factants can be recognized from the ir spectra of the sample. •.•oo •0o0 2500 2000 1800 1600 1400 1:200 1000 800 600 FREQUENCY (CM -I) Figure 2. Infrared spectrum of water-free nonvolatiles of a commercial shampoo (thin film on KBr plate) Quantitative Estimation of Total Soap and Anionic Sulfated (or Sulf onated) Surf actants The soap and artionic surfactants present are determined at an early stage of analysis to decide what further procedures to use. Absence of either soap or artionic surfactants may simplify the analysis by permitting

892 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS omission of some steps. The well-known cationic-anionic two-phase titra- tion, also known as the Epton-Barr titration (23, 24) method, is one way to do this. Separation of Cellulosic Materials Many shampoos contain cellulosic materials as thickening agents. Newburger (19) suggested using ethanol to precipitate water-soluble gums and then preparing a dried film on which the ir spectrum is run with the aid of water-repellent glass plates. The present authors found that in many cases some water must be re- moved from the sample in order to precipitate the cellulosic materials with ethanol. The coagulated cellulosic material can be removed by filtering through glass wool and purified by washing with fresh ethanol. To pre- pare the cellulosic material for recording its ir spectrum, it is preferable to make a viscous solution of it with water, deposit a thin film on a silver chloride optical window, and dry in a 105 øC oven. Separation of Alkanolamide from a Shampoo Containing lPropylene Glycol, Soap, and a Sulfated Detergent It was found that an alkanolamide can be isolated from a shampoo containing propylene glycol, soap, and a sulfated detergent by passing a solution of it through a cationic-anionic mixed bed ion exchange column such as Amberlite* MB-I. Propylene glycol is retained along with the ionic materials. Alkanolamide is recovered by passing ethanol through the column. In practice, a 2.4-cm i.d. glass column is packed with 50 ml of Amber- lite MB-I resin, 20-50 mesh, and is back-flushed with distilled water to obtain a good packing. A 2-g sample (preferably containing less than 2 meq of total anionic surfactant and soap) is dissolved in about 20 ml of water and passed through the column at 2 ml/min. After the column is rinsed with water (it was noted that very little alkanolamide was eluted with water alone), 200 ml of ethanol is passed through the column at about 4 ml/min, collecting all the effluent. After back-flushing of the resin in the column with just enough ethanol to get rid of the bubbles (without overflowing the ethanol), another 200 ml of ethanol is passed through the column, collected, and combined with the first effluent. To recover the alkanolamide, solvent is evaporated off. Figure 3 is the ir spectrum of an alkanolamide recovered by this procedure. * Rohm and Haas Go., Philadelphia, Pa.