FLUORESCENT WHITENING AGENTS IN COSMETICS AND LIQUID DETERGENT 287 Table II Recovery Tests Sample FWAs Sample prepared with the added FWAs standard (mg·kg-1) Analysis results (mg·kg-1) Mean recovery (%) Liquid detergent 85 0.5 0.440 ± 0.025 88.0 ± 5.0 210 0.462 ± 0.020 92.4 ± 4.0 220 0.451 ± 0.024 90.2 ± 4.8 351 0.485 ± 0.017 97.0 ± 3.4 353 0.410 ± 0.015 82.0 ± 3.0 85 5 4.19 ± 0.23 83.7 ± 4.6 210 4.47 ± 0.19 89.3 ± 3.8 220 4.31 ± 0.16 86.1 ± 3.2 351 4.77 ± 0.34 95.4 ± 6.8 353 4.26 ± 0.20 85.2 ± 4.0 85 50 45.0 ± 2.8 89.9 ± 5.6 210 46.6 ± 2.3 93.1 ± 4.6 220 45.4 ± 1.4 90.8 ± 2.8 351 48.0 ± 1.1 96.0 ± 2.2 353 43.0 ± 1.9 85.9 ± 3.8 Makeup water 85 0.5 0.429 ± 0.033 85.8 ± 6.6 210 0.440 ± 0.029 88.0 ± 5.8 220 0.451 ± 0.030 90.2 ± 6.0 351 0.407 ± 0.024 81.4 ± 4.8 353 0.416 ± 0.020 83.2 ± 4.0 85 5 4.43 ± 0.25 88.6 ± 5.0 210 4.41 ± 0.18 88.1 ± 3.6 220 4.43 ± 0.21 88.6 ± 4.2 351 4.61 ± 0.32 92.1 ± 6.4 353 4.27 ± 0.29 85.4 ± 5.8 85 50 46.5 ± 2.7 92.9 ± 5.4 210 47.7 ± 2.4 95.3 ± 4.8 220 47.8 ± 1.5 95.5 ± 3.0 351 51.7 ± 1.2 103.3 ± 2.4 353 49.9 ± 1.8 99.7 ± 3.6 Mask 85 0.5 0.431 ± 0.029 86.2 ± 5.8 210 0.406 ± 0.025 81.2 ± 5.0 220 0.410 ± 0.028 82.0 ± 5.6 351 0.422 ± 0.017 84.4 ± 3.4 353 0.507 ± 0.030 101.4 ± 6.0 85 5 4.41 ± 0.25 88.2 ± 5.0 210 4.36 ± 0.21 87.2 ± 4.2 220 4.53 ± 0.23 90.6 ± 4.6 351 4.92 ± 0.12 98.3 ± 2.4 353 4.37 ± 0.20 87.4 ± 4.0 85 50 41.2 ± 2.1 82.3 ± 4.2 210 44.8 ± 1.0 89.5 ± 2.0 220 46.2 ± 1.3 92.3 ± 2.6 351 48.4 ± 1.5 96.8 ± 3 353 48.2 ± 2.1 96.3 ± 4.2

JOURNAL OF COSMETIC SCIENCE 288 This might lead to the wrong results of determination. Although the problem could be solved by standard addition method, the method was rather tedious, which was not suit- able to batch tests. The situation could be effectively improved by decreasing the amount of sample from 1.0 to 0.2 g. In this case, the retention time of FWAs in standard solu- tions were consistent with the retention time of the same FWAs in liquid detergent samples. The optimized chromatographic conditions provided a good separation of fi ve FWAs in an appropriate analysis time. The developed method was adopted to determine the target analytes in a variety of makeup water, lotion, cream, emulsion, mask, and liquid detergent samples without FWAs. Results demonstrated that impurity compositions in the sam- ples had no interferential effects on the determination of the fi ve FWAs, indicating that the specifi city of the developed method was favorable. A typical chromatogram of fi ve FWAs standards is shown in Figure 4. ANALYTICAL FIGURES OF MERIT Linear responses to FWAs concentration were obtained from 0.100 to 100.0 μg·ml-1. The correlation coeffi cients were 0.9988–0.9995. The limits of detection were 0.1, 0.1, 0.05, 0.01, and 0.1 mg·kg-1 for FWA85, 210, 220, 351, and 353, respectively. The limits of quantifi cation were 0.4, 0.4, 0.2, 0.04, and 0.4 mg·kg-1 for FWA85, 210, 220, 351, and 353, respectively. The intraday and interday precisions were from 3.01% to 6.76% and 3.03–7.21%. The accuracy of the method was from -5.31% to +5.47%. The results demonstrated that the procedure provided acceptable accuracy and precision. The recovery was from 80.7% to 103.3% (Table II). These satisfactory values indicated that quantifi ca- tion by external calibration might be employed. The target analytes were stable for 24 h at room temperature and for 1 week at 4°C in the dark. Sample FWAs Sample prepared with the added FWAs standard (mg·kg-1) Analysis results (mg·kg-1) Mean recovery (%) Cream 85 0.5 0.440 ± 0.027 88.0 ± 5.4 210 0.412 ± 0.033 82.4 ± 6.6 220 0.452 ± 0.028 90.4 ± 5.6 351 0.505 ± 0.020 101.0 ± 4.0 353 0.463 ± 0.022 92.6 ± 4.4 85 5 4.04 ± 0.26 80.7 ± 5.2 210 4.22 ± 0.23 84.3 ± 4.6 220 4.30 ± 0.18 86.0 ± 3.6 351 4.55 ± 0.22 91.0 ± 4.4 353 4.64 ± 0.12 92.7 ± 2.4 85 50 44.6 ± 2.9 89.2 ± 5.8 210 44.4 ± 1.5 88.7 ± 3.0 220 45.0 ± 1.6 90.0 ± 3.2 351 47.9 ± 2.3 95.8 ± 4.6 353 44.6 ± 2.0 89.2 ± 4.0 Table II Continued