512 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS buying more cosmetics. This points to the cosmetics market becoming a mass market in the same way as the toiletries market. As the mass market is much more ruthless in dealing with over-priced, inferior products than the luxury market, now is the time to eradicate such products. Their existence can only serve to hold back the development of the mass market because an unsatisfied user can easily become a non-user. Those of us who are on the technical side of the industry should be the severest critics of its products. (Received: 7th May 1968)

THE ANALYSIS OF SYNTHETIC DETERGENTS 513 THE ANALYSIS OF SYNTHETIC DETERGENTS W. B. SMITH* A lecture delivered before the Society on 15th May 1963. The subject is introduced with a classification o• surface active agents that are used in all types o• detergents. This is •ollowed by a review o• the older qualitative tests and then an outline o• a new l•aper chromatographic l•rocedure. Quantitative analysis, confined to the determination o• the active constituents, is described under headings o• solvent extraction, colorimetric determination, anionic-cationic titration, and miscellaneous methods. THE WORD detergent nowadays suggests the packet of spray-dried powder used for domestic wash'rag purposes, but liquid products used in the same field may also come to mind. For the purposes of this paper other cleansing materials, namely shampoos and toothpastes, will be regarded as detergents soap is excluded as not failing within the definition of synthetic. However, only the organic surface active ingredients of the detergents will be considered. Most surface active agents which are used as detergents have molecules which are essentially linear and contain at one end groups having an affinity for water (hydrophilic groups), and at the other end groups which are anti- pathic to water (hydrophobic groups). Surface active agents are classed according to whether the active species is an anton, a cation, a non-ionizing group or an ampholytic group. An ampholytic group is one which may act as either anionic or cationic depending on the circumstances, principally oa the pH value of the solution. Hydrophobic groups may be classed under the headings of carboxylic acids (mainly naturally occurring acids), alcohols, hydrocarbons (mainly synthetic hydrocarbons derived from petroleum), and others (polyoxy propylene chains). Between the hydrophilic and the hydro- phobic group, the molecule may conta'm a linking group which may be an ether, ester, or amide. The listing and classification of possible structural groups is an essential prerequisite to the construction of a scheme of quali- tative analysis, and we still find the classification • drawn up five years ago to be a useful starting po'mt. The best systematic procedure is to identify first the hydrophilic group, then the linking group, if any, and lastly the hydrophobic group. QUALITATIVE ANALYSIS Hydrophilic groups One of the best tests for anionic and cationic active compounds is tc• *Marchon Products, Ltd., Whitehaven, Cumberland.