[Determination of eleven preservatives including bronopol in cosmetic by reversed-phase ion-pair chromatography]

Reversed-phase ion-pair chromatography was used to detect 11 preservatives including bronopol, esters of p-hydroxybenzoic acid (PHBA) in cosmetics. Zorbax C8 column was used and mobile phase was V (0.05 mol/L NaH2PO4):V(methyl alcohol):V(acetonitrile) = 50:35:15 with addition of hexadecyltrimethylammonium chloride (2 mmol/L) and the pH adjusted to 3.5 by using phosphoric acid. The wavelength 254 nm was selected for detection. Samples were extracted with methanol by ultrasonic method. The recoveries were 85%-107% and the relative standard deviations were 2.2%-7.5%.