MONITORING OF UV FILTERS BY HPLC 113 Table VII Results of Recovery (%) Study for 16 UV Filters Spiked into Cream and Lotion Matrixes Cream matrix Lotion matrix UV fi lters 15 ppm 20 ppm 25 ppm 15 ppm 20 ppm 25 ppm PABA 101.49 ± 7.75 98.14 ± 0.87 103.64 ± 0.65 106.32 ± 0.66 101.92 ± 0.77 100.97 ± 2.55 PBS 98.71 ± 1.96 103.04 ± 2.04 98.23 ± 2.18 99.07 ± 1.14 105.66 ± 0.20 96.25 ± 1.61 TDS 101.10 ± 7.85 97.35 ± 0.70 102.13 ± 0.73 105.57 ± 0.32 101.42 ± 0.50 100.68 ± 2.43 BZ-8 99.70 ± 7.61 96.52 ± 0.80 101.82 ± 0.59 105.24 ± 0.65 100.79 ± 0.69 99.95 ± 2.46 BZ-3 98.96 ± 7.69 95.96 ± 0.90 101.72 ± 0.61 104.34 ± 0.61 99.90 ± 0.73 99.08 ± 2.44 IMC 99.68 ± 7.68 96.62 ± 0.88 101.93 ± 0.58 103.79 ± 0.60 99.36 ± 0.75 98.73 ± 2.39 DT 96.47 ± 3.66 97.97 ± 2.80 97.10 ± 1.90 94.90 ± 0.54 97.35 ± 0.73 95.64 ± 0.29 MBC 101.69 ± 8.15 97.15 ± 0.88 104.00 ± 0.86 105.43 ± 0.78 99.16 ± 0.83 100.04 ± 2.61 OC 101.17 ± 7.73 97.82 ± 0.88 102.86 ± 0.59 105.28 ± 0.67 100.86 ± 0.61 100.22 ± 2.39 MA 101.80 ± 7.09 99.02 ± 0.69 104.23 ± 0.50 104.30 ± 0.59 100.06 ± 0.78 99.52 ± 2.27 ED-PABA 99.07 ± 7.76 95.88 ± 0.90 100.79 ± 0.59 102.75 ± 0.41 98.08 ± 0.81 97.55 ± 2.33 BMDM 97.95 ± 7.53 94.98 ± 0.73 99.47 ± 0.50 100.82 ± 0.35 96.70 ± 0.76 95.03 ± 2.27 EMC 98.69 ± 7.68 95.47 ± 0.77 100.50 ± 0.60 102.04 ± 0.52 97.41 ± 0.75 96.81 ± 2.40 DBT 100.56 ± 7.79 97.62 ± 0.70 102.07 ± 0.66 104.60 ± 0.48 100.13 ± 0.73 99.45 ± 2.37 EHT 100.63 ± 1.47 104.94 ± 2.70 96.74 ± 0.51 98.39 ± 0.83 101.01 ± 1.35 95.67 ± 2.30 MBBT 108.09 ± 4.10 116.54 ± 7.89 114.42 ± 5.47 109.99 ± 1.31 116.27 ± 0.33 116.21 ± 0.45 Table VIII Repeatability for UV Filters Spiked into Cream and Lotion Matrixes Cream matrix Lotion matrix 15 ppm 20 ppm 25 ppm 15 ppm 20 ppm 25 ppm Area SD Area SD Area SD Area SD Area SD Area SD DT 286.12 0.30 387.50 0.61 476.42 0.15 274.78 0.30 380.18 0.20 464.21 0.48 MBC 466.10 0.37 572.61 0.93 772.14 1.32 458.43 0.72 587.15 0.80 748.21 0.63 MA 97.68 0.22 123.00 0.46 162.51 0.35 95.33 0.24 124.40 0.14 156.05 0.39 BZ-3 252.85 0.19 317.29 0.55 421.10 0.67 254.42 0.24 330.71 0.34 413.66 0.34 BZ-8 222.37 0.14 278.32 0.17 368.95 0.21 224.06 0.17 291.35 0.43 364.42 0.23 BMDD 742.39 0.41 934.14 1.05 1232.23 2.36 726.61 1.15 953.81 1.43 1185.67 1.48 EHT 855.65 0.96 1201.83 2.73 1399.76 1.97 828.84 0.95 1157.96 2.45 1411.88 1.67 OC 199.36 0.06 248.77 0.39 328.31 0.31 197.43 0.18 257.65 1.27 321.96 0.14 ED-PABA 594.61 0.13 742.13 0.65 981.79 2.37 585.68 0.53 761.45 1.34 954.65 0.91 EMC 366.13 0.30 457.38 0.45 605.95 0.56 359.64 0.41 467.40 0.31 586.86 0.79 PABA 750.58 0.54 940.09 0.57 1246.49 0.56 750.68 0.68 978.19 1.21 1222.55 0.93 PBS 726.14 0.21 1003.63 0.66 1145.22 0.99 705.89 0.41 1008.05 0.98 1147.44 0.03 IMC 601.31 0.24 753.15 0.56 998.28 0.66 596.60 0.43 775.84 0.52 972.62 0.77 DBT 636.08 0.57 791.23 0.77 1047.98 0.58 632.48 0.62 825.07 0.68 1046.02 0.56 MBBT 895.84 0.89 1123.17 0.75 1478.59 1.05 885.72 0.57 1154.94 0.88 1457.26 0.82 TDS 278.22 0.79 402.67 0.67 488.45 1.07 276.65 1.07 388.13 1.22 478.60 0.67

JOURNAL OF COSMETIC SCIENCE 114 sunscreen samples are measured. The mixture of stock solutions was readily precipitated at 4°C. ANALYTICAL APPLICATION The method was applied to 23 commercial sunscreens to represent various types, such as cream, lotion, makeup, powder, and oil. The sunscreens included one to fi ve UV fi lters, of which BMDM and EMC were predominantly contained in the products. However, a sun- screens containing DT, BZ-8, or PABA was not commercially available in a local market. The sunscreen samples were homogenized in MeOH under sonifi cation to analyze in HPLC (Figure 3). For the recovery of EHT and MBBT, the sunscreens were additionally prepared in THF. The recoveries of UV fi lters accounted for 90.12–125.15%, compared with the label claims for each sunscreen (Table X). These results fulfi lled the criteria for sunscreens that are controlled to contain more than 90% of the label claim but not to exceed the maximum authorized concentration listed in Table I. CONCLUSIONS Consequently, simultaneous determination of 16 UV fi lters was performed using HPLC detected at 300, 320, and 360 nm without any analytical predicament. The mobile phase was used as a gradient, with MeOH and phosphate buffer adjusted to pH 4.0. The LODs of the UV fi lters were 0.08–1.94 μg/ml, and the LOQs were 0.24–5.89 μg/ml. The lin- earity displayed up to 50 ppm. According to the properties of UV fi lters, MeOH or THF were utilized for sample preparation. MeOH was used as an extracting solvent for DT, Table IX Results of Stability Test for 16 UV Filters Correlation coeffi cient (R2) UV fi lters 1 day 3 day 6 day PABA 0.9997 0.9994 0.9994 PBS 0.9996 0.9994 0.9994 TDS 0.9996 0.9993 0.9994 BZ-8 0.9996 0.9985 0.9994 BZ-3 0.9996 0.9994 0.9984 IMC 0.9997 0.9994 0.9995 DT 0.9996 0.9993 0.9993 MBC 0.9997 0.9994 0.9992 OC 0.9997 0.9993 0.9994 MA 0.9993 0.9974 0.9946 ED-PABA 0.9996 0.9994 0.9994 BMDM 0.9996 0.9994 0.9930 EMC 0.9996 0.9993 0.9915 DBT 0.9996 0.9993 0.9994 EHT 0.9996 0.9992 0.9993 MBBT 0.9989 0.9456 0.8525