RISK-BEARING SUBSTANCES IN COSMETICS 181 Sample numbers column numbers i5585 i585o i588o 42090 45170 45396 Figure 3. Analytical results: lipstick colours. Analysis of the colour com- position of 38 commercial lipstick samples. Experimental The determination starts with a quick (ca 20 min) estimation of the concen- tration levels by tic on 10 cm precoated plates and visualization by iodine vapour. This makes it possible to determine optimum amounts for the spots of the main identification procedure. Thin-layer chromatography. Two-dimensional tlc on 20 x 20 cm silica plates was chosen for this main identification. The 'crude' extracts were 'cleaned-up' in the first direction, thus permitting excellent resolution in the second. The spots are easily visualized by iodine vapour, which colours all the classes of intermediates, the aromatic diamines, the aminophenols as well as the polyphenols.

182 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table IV. The most important types of oxidative hair colour intermediates Substituents No. of Position Base isomers Abbreviation commonly used Diamino 3 ortho meta para Dihydroxy 3 ortho meta para Trihydroxy 3 1.2.3 1.2.4 1.3.5 Hydroxy 3 2. amino 3. 4. Methyl 6 2.3 diamino 2.4 2.5 2.6 3.4 3.5 Hydroxy 6 2.3 diamino 2.4 2.5 2.6 3.4 3.5 Diamino 6 2.3 methyl 2.4 ether 2.5 2.6 3.4 3.5 Nitro 6 3 nitro diamine 4 nitro 2 nitro 4 nitro 5 nitro 2 nitro Hydroxy 2 tt Diamino 6 2.3 2.4 2.5 2.6 3.4-3.5 phenylenediamine phenylenediamine phenylenediamine dihydroxybenzene = pyrocatechol dihydroxybenzene = resorcinol dihydroxybenzene = hydroquinone trihydroxybenzene = pyrogallol trihydroxybenzene = hydroxyhydroquinone trihydroxybenzene = phloroglucine aminophenol aminophenol aminophenol toluylenediamine toluylenediamine toluylenediamine toluylenediamine toluylenediamine toluylenediamine diaminophenol diaminophenol-- arnidol base diaminophenol diaminophenol diaminophenol diaminophenol diaminoanisole diaminoanisole diaminoanisole diaminoanisole diaminoanisole diaminoanisole 1.2.phenylenediamine 1.2.phenylenediamine 1.3.phenylenediamine 1.3.phenylenediamine 1.3.phenylenediamine 1.4.phenylenediamine naphthol naphthol diaminopyridine diaminopyridine diaminopyridine diaminopyridine diaminopyridine OFD MFD PFD PCT RES HCH PGL PHL 2AF 3AF 4AF 24TDA 25TDA 24DAF 24DAA 4NOFD 2NPFD AN BN 26DAP