330 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS The matrix was added without any changes in conditions by a post-column that has already been employed for routine analysis. We chose 30 compounds that are frequently formulated into cosmetics as so-called additives, such as antioxidants, preservatives, UV absorbers, and humectants, and as active ingredients, at 0.01-1.0% levels. First we established their detection limits by CF-FAB MS, using glycerin as a matrix. Based upon extensive screening studies, we then conducted optimization studies on both instrumental and analytical conditions for CF-FAB HPLC/MS, using a mixture of methanol and water as the mobile phase. We found that post-column addition of a matrix solution containing methanol and glycerin allowed us to adjust the methanol concentration at the ion source so as to obtain better sensitivity and S/N ratio. Although CF-FAB MS has been applied successfully to many compounds (4-9), the results of our comprehensive and systematic studies provide basic information to extend the applicability of the method, especially for analysis of components of complex mix- tures and unknown compounds. In addition, we applied the method to a quantitative analysis of hair lotion containing pantothenylethylether, which gave the highest sensitivity (5 pg) among the compounds studied here. EXPERIMENTAL FLOW INJECTION CF-FAB MS A micrometric pump (Milton Roy, FL) supplied the solvent to the injector. The injector was a Rheodyne 7410 (Rheodyne, CA) with a loop volume of 0.5 •I. This system was connected to a Finnigan MAT (Bremen, Germany) CF-FAB probe by means of a 1.5-m x 75-•m I.D. fused-silica capillary (SGE, Melbourne, Australia). The solvent was 50% (v/v) aqueous methanol containing 1% (v/v) of glycerin, and the flow rate was 7 pA/min. CF-FAB LC/MS This system, a schematic diagram of which is shown in Figure 1, consisted of an HPLC (glycerin / water) (glycerin / methanol) PUMP (mobile phase) ]COLUMN CFFAB MS I mixer splitter [ Figure 1. Schematic diagram of CF-FAB LC/MS system.

ANALYSIS OF COSMETIC INGREDIENTS 331 unit, a mixer, and a splitter connected to the Finnigan MAT CF-FAB probe by means of a 2.0-m ) 75-•m I.D. fused-silica capillary. The HPLC unit consisted of an LC-9A pump (Shimadzu, Kyoto, Japan), a Rheodyne 7125 injector (Rheodyne, CA) (20 •I), a CAPCELL PAK C18 SG120 reversed-phase column (250-mm) 1.5-mm I.D) (Shiseido, Tokyo, Japan), an SPD-6A UV detector (Shimadzu), and two LC-9A pumps for methanol and water, both containing 15% (v/v) glycerin to be added as a matrix solution post-column. The flow rates of the mobile phase and post-column matrix solution were 100 •l/min and 50 •I/min, respectively. The split ratio was l: 19, and so the flow rate to the ion source was ca. 7.5 •l/min and the concentration of glycerin was ca. 5% (v/v). MASS SPECTROMETRY The CF-FAB probe was fitted to a Finnigan MAT 90 double-focusing mass spectrom- eter, operating at 5 kV. The Finnigan MAT ICIS data system was used. The instrument was equipped with an FAB gun (Ion Tech, Teddington, U.K.) using xenon and pro- ducing a beam of neutral atoms with 7 kV energy. The FAB spectra were recorded in the positive-ion or negative-ion mode by scanning from m/z 70 to 2000 or from 100 to 800 with a scan speed of 5.0 per decade. The resolution was 1000 (10% valley defini- tion) during the measurement. A stainless-steel target with a gold-plated drain channel was used (10). An exchangeable ion volume with a wick was applied to reduce con- tamination problems. The wick, made from compressed paper, was placed at the bottom of the ion volume. Additional vacuum pumping at the ion source housing was obtained by using a liquid nitrogen trap. The temperature of the ion source was kept at 50øC to improve the evaporation of the mobile phase (11). REAGENTS Cosmetic ingredients to be formulated at the 0.01-1% level were purchased from Tokyo Kasei Kogyo (Tokyo, Japan) ingredients 22, 28, and 29 were purchased from Sigma (St. Louis, MO). Chemical names and molecular weights of these ingredients are sum- marized in Table I along with additive classification. Methanol was obtained from Merk (Darmstadt, Germany). Glycerin (99.5% pure) was purchased from Aldrich (Wiscon- sin). SAMPLE PREPARATION Applicability study of CF-FAB to cosmetic analysis. Solutions (1, 10, 100, 1000 ppm)were prepared in water (compounds 1-6, 20, 21, 23-25), 50% methanol (7-13, 22, 26, 28-30), and methanol (14-19, 27). An aliquot of 0.5 •1 was injected three times. The amounts injected were therefore 0.5, 5, 50, and 500 ng, respectively. Optimization study on methanol concentration at the ion source using the CF-FAB LC/MS. Solutions of 500 ppm of eight selected ingredients were prepared in 20% methanol (compounds 1, 3, 5), 50% methanol (8, 30), and 80% methanol (12, 13, 15), as used for the mobile phase of the HPLC system. The injection volume was 2 •1, and the amount actually introduced into the CF-FAB LC/MS was 50 ng, since the split ratio was set at 1:19.