HPLC Determination of Vanillin and Ethyl Vanillin in Cosmetics

For creamy sample, 1.0 g was taken and dissolved in 4 mL of tetrahydrofuran, and then its volume was made up to 10 mL with methanol. For emulsion, aqueous or solid sample, 1.0 g was taken and methanol was added to make its total volume to near 5 mL, the mixture was shaked for 1 min by swirling. The total volume was then made up to 10 mL with methanol. For either case, the sample solution was extracted ultrasonically for 15 min, and centrifuged for phase separation. The supernatant was taken and chromatographic separation was made by using ZORBAX Eclipse Plus C₁₈ column as the separation column and mixture composed of methanol and 1.5% (φ) acetic acid solution (mixed in the volumic ratio of 35 to 65) as the mobile phase. UV-detection at 280 nm was adopted. Linear relationships between values of peak area and mass concentration of vanillin and ethyl vanillin were found in the same range of 0.5-100 mg·L^-1, with same detection limits (3S/N) of 0.2 mg·kg^-1. Test for recovery was made by standard addition method using a blank sample as matrix, values of recovery found were ranged from 91.3% to 97.0%. Values of RSD (n=6) found were in the range of 1.0%-1.7%.