Determination of Free Formaldehyde in Cosmetic by HPLC Combined with Online Derivatization

Free formaldehyde in cosmetic was determined by HPLC combined with automatic online derivatization. Free formaldehyde in cosmetic samples was extracted by acetonitrile and reacted efficiently with 2,4-dinitrophenylhydrazine in acetonitrile-acetic acid solution for 2 min. The formaldehyde derivative was separated on an Agilent C₁₈ chromatographic column with acetonitrile-water (65+35) as the mobile phase for elution, and then detected by DAD at the wavelength of 355 nm. The linear range of formaldehyde was 1.0-20.0 mg·L^-1, with the lower limit of determination (10S/N) of 50 mg·kg^-1. Recovery rates obtained by standard addition method were in the range of 83.0%-98.4% and RSDs (n=6) were in the range of 3.4%-7.8%.