Simultaneous Determination of 7 Benzoate Compounds in Cosmetics by RP-HPLC

RP-HPLC was applied to the simultaneous determination of 7 benzoate compounds in cosmetics. The sample (about 0.5 g) was extracted ultrasonically for 30 min with 8 mL of methanol. After cooling,the solution was made up to 10 mL with methanol. Part of the above sample solution was centrifugated for 5 min at the speed of 5 000 r·min^-1. The Supernatant was filtered with organic phase needle type filter head. ECOSIL 120-5-C₃₀ chromatographic column was used as separation column, and methanol (6+4) solution was used as mobile phase. Detection at 229 nm was adopted in the determination. Linear relationships between values of peak area and mass concentration of the 7 benzoate compounds were kept in the same range of 1.25-50.00 mg·L^-1, with lower limits of determination (10S/N) of the method in the range of 4-8 mg·kg^-1. On the base of blank sample, test for recovery was made by standard addition method; values of recovery found were in the range of 88.8%-97.2%, with RSDs (n=6) of recovery amounts in the range of 2.2%-5.3%.