414 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS technique has enabled the analytical chemist to separate most of the components in a volatile mixture. Identification is accomplished by comparing the retention time of the unknown on several columns with that of a standard. Detection systems that have been used with capillary GC are based on thermal conductivity, hydrogen flame ionization, argon ionization, electron affinity, and coulometric principles. Several review articles and books have been published on this subject (50-52). The increase in use of mass spectrometers throughout the industry is primarily due to the development of quadrupole mass filters capable of separating ions on the basis of their mass to charge ratio (m/e) solely by means of an electric field (53). The development of this type of mass filter into commercially available instruments has lowered the cost of mass spectrometers. Coupled with computers capable of processing information rapidly, the mass spectrometer has become a universal detector for absolute identification. The coupling of capillary GC to the mass spectrometer has allowed this technique to emerge as the primary approach to fragrance analysis. Standard libraries of compounds are available for computer comparison of data, or libraries containing only fragrance compounds can be built. With these libraries residing within the computer, reverse searching capabilities are available, along with the ability to quantitate volatile mixtures. A second emerging technique for the analysis of fragrance is GC-FTIR. The separation is again accomplished by capillary GC, followed by introduction of the sample into a light pipe where an infrared spectrum is obtained. As in mass spectroscopy, libraries of IR data are becoming available, along with computer search programs. Several researchers are combining both these techniques so that the IR and MS of a separated component can be obtained from a single run. The computer can then cross-check both the IR and MS of a given separated compound and assign the most probable structure based on both of the spectroscopic techniques employed. More recently, HPLC used alone or interfaced with a mass spectrometer has shown promise in the analysis of fragrance compounds (54). AMINO ACIDS, PROTEINS, AND POLYMERS A number of cosmetic product categories over the last several years have incorporated protein, amino acids, and polymers as raw materials in their formulations. The analysis and quality control of these ingredients is of increased importance to the cosmetic analytical chemist. The traditional method for the analysis of amino acids is based on elution chromatography from buffered columns of ion-exchange resin. The separated components are reacted with ninhydrin and quantitated by visible spectrophotometric detection. The analysis of proteins by this method is accomplished by hydrolyzing the material in hydrochloric acid followed by separation and quantitation of the amino acids. The latest approach to amino acid analysis has used HPLC combined with either pre-column or post-column derivitization. Researchers have separated the phenylthio- hydantoin derivatives of all 20 common amino acids using a reverse phase C•8 column eluted with a concave ethanol gradient in aqueous ammonium acetate at pH = 5.1 (55). Researchers have separated the amino acids normally found in protein hydrolysates within 45 minutes using normal-phase chromatography on NH2-silica (56). Detection was accomplished with either ninhydrin or o-phthalaldehyde. Reproducibility of the

ANALYTICAL CHEMISTRY OF COSMETICS 415 retention times allowed peak-height or peak-area measurements to be used for quantitation in the range of 10 pmol to 25 nmols. Pre-column conversion of the amino acids to their damsyl derivative followed by HPLC also has given good separation of all 20 common amino acids (57). Gas chromatography coupled with flame photometric detection is used for the analysis of sulfur-containing amino acids (58). High pressure (performance) liquid chromatography of proteins is becoming more prevalent in the literature, with the experimentation focusing on various support phases and buffer systems. For example, peptides varying in size from di- to decapeptide have been separated on phenyl-corasil, Poragel PN, and Poragel PS using reverse phase conditions with acetonitrile-water (59) as the mobile phase. Researchers have modified this method with the addition of phosphoric acid to the mobile phase (60,61). The analysis of proteins has also been reported using gel-permeation chromatography (62) and nuclear magnetic resonance spectroscopy (63). In the case of gel permeation chromatography, the chemist is using the separation technique of HPLC to obtain molecular weight distribution (64) rather than identifica- tion of the fraction separated. Cationic polymers used in hair fixatives can be analysed using gel-permeation chromatography to obtain an average molecular weight. Polymer chain length is no doubt related to product performance therefore, improved methods of analysis using gel permeation chromatography for charged polymers should be forthcoming. TRACE CONTAMINANTS Trace analysis of cosmetic raw materials is one of emerging concern for the cosmetic analytical chemist. During the past several years, the regulatory climate has involved the cosmetic industry in three major areas: the analysis of nitrosamines, the analysis of dioxane, and the analysis of specific trace contaminants in raw material dyes used in cosmetic finished products. The analytical methodology used to determine the level of contaminants of concern will be discussed. For the past five years, the Cosmetic, Toiletry and Fragrance Association (CTFA) Nitrosamine Task Force has been studying trace level contamination of cosmetic raw materials, with their major focus the determination of N-nitrosodiethanolamine (NDEIA). Since NDEIA is a polar-nitrosamine, its determination stands apart from the general methodology for the analysis of nitrosamines. Volatile nitrosamines have been detected by gas chromatography employing either a nitrogen specific detector or a thermal energy analyzer (TEA) (65,66). Initial research which found trace levels of NDE1A in cosmetic products used a TEA (67). The instrument contains a pyrolyric oven which cleaves the weak N=N=O bond to produce NO. An inert gas is used to sweep the NO into an ozonator which then forms activated NO 2. When the NO2 decays to the ground state, the emitted energy is detected. A gas chromatograph is used at the front end of the pyrolysis oven for the initial separation. This instrument for the most part is nitrosamine specific and is currently the leading analytical technique used to meet government standards for volatile nitrosamines. The cosmetic chemists' problem is more difficult, since NDEIA is polar and appears sometimes in trace quantity in complex mixtures. The CTFA has developed methodol-