34 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS human body. This has given rise to a sophisticated, yet practical, toilet•y and cosmetic market with world wide appeal. As more and more scientific knowledge is acquired and applied, so the need to determine the nature and level of product ingredients becomes of paramount importance. Fortunately, the advances in analytical techniques have been as dramatic and timely as the advances in scientific knowledge. PRELIMINARY CONSIDERATIONS First we must ask 'Why do we need to analyse these products ?' and this question must be answered before any analysis is considered, because the analytical route depends on the kind of information required. Specialized techniques are expensive to acquire and run, but results not easily available by other means can be obtained and providing these results are applied judiciously, the economics can be acceptable. The problems presented to the analyst vary from the extreme of a so- called 'complete' analysis (or perhaps a general idea of the product formula), through estimations of amounts of particular ingredients that are present or available, down to determinations of trace amounts of possibly harmful impurities. Examples drawn from the author's experience and the literature illus- trate some of the ways in which specialized techniques can be applied to the analysis of toilet preparations and cosmetics together with the kind of information that can be obtained. The cosmetic and toiletries market consists of a range of products of different physical forms (powders, lotions, creams, pastes, dispersions, suspensions, moulded solids etc.) in a variety of packs (bottles, jars, tubes, tins, aerosols) further fragmented into products for special application to every area of the human frame whether male, female or child, not forgetting multi-purpose and unisex products. ANALYTICAL APPROACH Basically there are two situations--one in which we know what we are looking for, and another in which we are dealing with complete unknowns. However, these can be considered together since in each case the substance is nearly always surrounded by a complex matrix, so direct analysis is usually not feasible because a prerequisite for most of the instrumental techniques is that the substance to be identified or estimated must be in a reasonably pure state.

ANALYSIS OF COSMETICS AND TOILETRIES 35 This means that good separation techniques are also needed, and fortunately the development of these has kept pace with the instrumental techniques. So today's analyst follows a two-stage procedure. (1) Separation and isolation of the various components of interest. (2) Characterization, identification and estimation. The separation techniques are a mixture of classical and new. Chromato- graphy is the most versatile of the new techniques and once identification has been established has the added advantage that it can also be used for estimation. The list of instrumental techniques has been limited to those which are particularly useful for the analysis of cosmetics and toilet prepara- tions. An even wider range has been used for background studies. Attention is given to the application of techniques and a description of the underlying principles is not included but a bibliography for further reading is appended. It is worth noting that most of the raw materials used in this industry are not single chemical entities but are mixtures, homologous series, by- products etc. and our modern separation techniques can separate virtually everything given the right conditions. It is important to know, therefore, what components are likely to be present in raw materials before drawing conclusions about the analysis of an unknown product. SEPARATION TECHNIQUES New Column chromatography Ion-exchange chromatography Liquid chromatography (lc) Gas chromatography (gc) Gel permeation chromatography (gpc) Thin layer chromatography (tlc) Classical Dialysis Diffusion Distillation Solvent extraction etc. CHARACTERIZATION AND IDENTIFICATION TECHNIQUES Spectroscopy Ultra-violet spectrophotometry (uv) Visible spectrophotometry Infra-red spectrophotometry (ir) Flame emission spectrophotometry Atomic absorption spectrophotometry (aas) Fluorescence spectrophotometry