Determination of 5 Fluorescent Whitening Agents in Cosmetics and Detergent by High Performance Liquid Chromatography

A method of high performance liquid chromatography was developed to determine 5 fluorescent whitening agents, including C.I. 85, C.I. 210, C.I. 220, C.I. 351 and C.I. 353, in cosmetics and detergent. The sample (1.000 g of cosmetics or 0.500 g of detergent) was mixed well with 10.0 mL of acetonitrile (1+2) solution by vortex oscillation for 1 min, and then ultrasonically extracted for 10 min. After the mixture was centrifugated at 10 000 r·min^-1 for 5 min, the supernatant was filtered through a 0.22 μm filter membrane, and seperated on a MG C₁₈ column (250 mm×4.6 mm, 5 μm), with a mixture of acetonitrile and 10 mmol·L^-1 ammonium acetate solution (containing 2 mmol·L^-1 di-n-hexyl-ammonium acetate) for gradient elution. A diode array detector was used for detection at the wavelength of 350 nm. Linear relationships were found between peak areas and mass concentrations of the 5 fluorescent whitening agents in the same range of 5.0-100 mg·L^-1, with detection limits (3S/N) in the range of 4-20 mg·kg^-1, and lower limits of determination (10S/N) in the range of 15-70 mg·kg^-1. Tests for recovery was made to blank samples at mass contentrations of 5.0, 50, 100 mg·L^-1, giving values of recovery between 80.3% and 111%. The 5 fluorescent whitening agents in the samples were determined in parallel for 6 times, and the relative standard deviations of the measured values were between 2.4% and 8.9%.