Application of the Analytical Mode of QAMS to HPLC Determination of 15 Sunscreen Agents in Sunscreen Cosmetics

CAPCELL PAK C₁₈ chromatographic column, with column temperature of 30℃ and volume of sample introduction of 10.0 μL, and mixtures of (A) methanol, (B) tetrahydrofuran, and (C) 0.008 2 mol·L^-1 HClO₄ solution in various ratios as mobile phases in gradient elution were selected for HPLC separation of standard for 15 sunscreen agents which were used frequently in preparation of sunscreen cosmetics. Ultraviolet detections at the wavelength of 311 nm were made for the determination of the 15 compounds. In analysis of substantial cosmetic sample, 0.25 g of the sample was ultrasonically extracted with 15 mL of a mixed solvent of methanol, tetrahydrofuran, water and perchloric acid (250:450:300:0.2 by vol.) for 30 min, and the volume of the extract was made up to 25.0 mL with the mixed solvent. After centrifugation, 1.0 mL of the supernatant was taken, and diluted to 10.0 mL with the mixed solvent. The solution was then filtered through 0.45 μm filtering membrane, and the filtrate was used for HPLC analysis according the working condtions of the instrument. It was shown that good linear relationships between values of peak areas of the 15 sunscreen agents found and their respective mass concentrations in definite ranges were obtained. Relative correction factors and relative retention times of 14 of the 15 sunscreen agents were calculated from data of their mass concentrations and peak areas by taking diphenyl ketone-3 as reference. Based on these parameters, condition of analytical mode of QAMS as applied to the simultaneous HPLC determination of the 15 compounds in sunscreen cosmetics was established. Some factors, e.g. types of the chromatographic column and the chromatograph used, temperature of the LC column and volume of sample solution introduced that may effect the values of relative correction factors and relative retention times were also studied in detail. As shown by the testing results, when the qualified type of chromatographic column was chosen, the QAMS mode could be effectively used for the simultaneous determination of the 15 compounds. The proposed method was used in analysis of 6 samples from various batches, giving results in consistency with those given by the conventional method. Significant efficiency in saving of cost and time for analysis was shown by the mode of QAMS.