DETERMINATION OF CATIONIC PRESERVATIVES IN COSMETICS BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A simple method by high performance liquid chromatography (HPLC) was developed for the simultaneous determination of 4 preservatives in cosmetics, chlorhexidine gluconate (GCH), benzalkoniumchloride (BzAC), benzethonium chloride (BzEC) and cetylpyridinium chloride (CPC). A sample of a cosmetic containing GCH, BzAC, BzEC and CPC was dissolved in tetrahydrofuran (THF) or methanol (MeOH). For the elution of BzAC, BzEC and CPC, the sample was passed through a Bondelute SCX cartridge. After washing the cartridge with MeOH, BzAC, BzEC and CPC were eluted with 0.1 M NaClO4/MeOH. On the other hand, for the elution of GCH, the sample was passed through Bondelute CBA cartridge. After washing the cartridge with MeOH, GCH was eluted with a solution of 0.2 M KH2PO4-CH3CN (1:1). The optimum condition fro the separation by HPLC of 4 preservatives in cosmetics was as follows: column, TSK gel ODS 80 TM (4.6 mm i.d. X 150 mm); mobile phase, CH3CN-H2O-THF-acetic acid (40:40:20:0.2) containing 0.2% sodium lauryl sulfate, 1.2 ml/nub; column temperature, 50 degrees C; detection wavelength, 263 nm. Recovery of 4 preservatives in 10 samples of cosmetics (6 different types of cosmetics) was almost more than 95%. Detection limits of GCH, BzAC, BzEC and CPC were 0.00003%, 0.001%m 0.0002%m 0.00005%, respectively (S/N ratio = 10, 10 mu l,0.005 a.u.f.s, lambda(max)).