SIMULTANEOUS DETERMINATION OF HEAVY METALS 445 Table II Relative Standard Deviations (RSDs), Linear Ranges, Correlation Coefficients, and Detection Limits RSD (%) Linear range Correlation Detection limit Metal Retention time Peak area (µg ml- 1 ) coefficients (r2) (µg 1-I) Pb 0.210 1.02 2.5--40.0 0.9986 41 Fe 0.166 1.13 0.1-1000 0.9995 3.4 Cu 0.214 1.08 0.1-10 0.9992 5.5 Ni 0.184 0.99 0.1-40 0.9997 6.1 Zn 0.16 1.04 0.2-1000 0.9992 5.8 Co 0.137 1.16 0.2-200 0.9991 3.4 Cd 0.144 1.24 0.8-12.5 0.9988 19 Mn 0.072 0.98 0.2-100 0.9995 9.8 the detection limits lower, and so this could be accepted as a satisfactory process for safe cosmetic products. METHOD VALIDATION (SPECIFICITY, LINEARITY, DETECTION LIMITS, PRECISION, AND ACCURACY [RECOVERY RA TE}) Sharper peaks were produced, with good peak separation. The specificity of each metal was validated by the evaluation of the peak homogeneity from the UV spectrum of the photodiode array detector. The method showed a good linearity (r2 0.999) with the test metals for concentrations ranging from 0.1 to 1000 µg/ml. Using injections of 200 µl, the detection limits (signal-to-noise ratio of 3:1) of this method were 41, 3.4, 5.5, 6.1, 5.8, 3.4, 19, and 9.8 µg/1 for Pb2+, Fe2+, Cu2 + , Ni2+, Zn2+, Co2 + , Cd2 + , and Mn2 + , respectively. The repeatability was determined by multiple analysis of a standard solu­ tion. The relative standard deviations (RSDs) of the retention time and the peak area were less than 0.21 % and 1.24%, respectively. The linearity, the detection limits, and the relative standard deviations are summarized in Table II. The recovery rates were 97-104%, shown in Table III. ANALYSIS OF SAMPLES As a validation of the analytical technique, coloring agents and cosmetic products could be analyzed. Figure 2 shows the chromatogram of all the metals in a coloring agent. The Table III Concentrations and Spiked Recoveries of Metals in Eye Shadow Concentration Spiked Found Recovery Metals (µg ml- 1 ) (µg ml- 1 ) (µg ml- 1 ) (%) Pb 50 50.56 101.1 Fe 75.7 5 80.31 99.5 Cu 2.55 5 7.38 97.7 Ni 5.76 5 11.04 102.6 Zn 50.34 5 55.82 100.9 Co 0.26 5 5.34 101.5 Cd 5 4.88 97.6 Mn 17.83 5 23.65 103.6

446 JOURNAL OF COSMETIC SCIENCE 450 mAU 400 350 300 250· 200 150 100 50 1-Fe WVL:530nm 4-Zn 2-Cu 6-Mn \- 3-N11 ' 5-C J\ � ... \ 0 A. o.a-------�--....Wljll.,. ....... __ � ..... � min -50,11,,..---.-..--.........-...-.-....-� eta fa 4.o B:o rto 10:0 12·.o 14:0 1s:o 1a:o Figure 2. Chromatogram of Ultramarine Pink coloring agent. concentrations of the metals in coloring agents and cosmetic products are presented in Tables IV and V, respectively. Lead and cadmium, which can cause serious problems of safety on the skin, were not detected in the coloring agent and cosmetic product. Copper, nickel, cobalt, and man­ ganese were not detected in all of the cosmetic products except some of the coloring agents. This means that all the cosmetic products in the skin test are safe from heavy metals except for some coloring agents. To prevent cosmetic products from containing heavy metals, which are separated from raw materials, quality control for heavy metals is definitely necessary for both cosmetic products and their raw materials. DISCUSSION To determine the heavy metals, ICP-MS, flame AAS, and HPLC have been compared. ICP-MS and flame AAS are fast and sensitive for the determination of heavy metals. However, if we analyze water-soluble heavy metals in cosmetic products by using ICP-MS or the flame AAS method, it is difficult to determine the exact amount of heavy Table IV Determination of Metals in Coloring Agents Concentration (µg ml - 1 ) Samples Pb Fe Cu Ni Zn Co Cd Mn Ultramarine Pink 75.7 2.5 5.7 50.3 0.3 17.8 Ultramarine Blue 156.3 1.8 100.9 0.5 34.9 Cobalt Blue 2.2 0.4 21.6 177.9 0.8 Chromium Oxide Green 30.2 0.4 27.1 8.4 U nipure Green 0.9 1.2 28.5 1.0. Black 719.9 13.8 80.1 Mapico Black 789.8 17.0 7.7 Mapico Red 666.8 6.6 103.3 2.9 67.7 Soft-Tex Red 616.9 16.6 9.4 Mapico Yellow 541.2 4.5 22.9 7.2 16.9 Socovit Brown 19.5 31.1 4.5 27.5 Above are the average concentration values of 3-time injection.