Abstract:

A high performance liquid chromatography （HPLC） method was established for the simultaneous determination of 10 quaternary ammonium salt compounds （benzalkonium chloride, benzethonium chloride, dequalinium chloride, lauralkonium chloride, methamphetamine chloride, octadecyl dimethyl benzyl ammonium chloride, cetyltrimethylammonium chloride, cetylpyridinium chloride, cetrimide bromide, and cetrimide chloride） in oral care toothpaste. Acetonitrile was used as the extraction solvent, with a mobile phase of 60 mmol/L ammonium acetate buffer solution （pH=6.0） and acetonitrile for gradient elution. The column temperature was 30 ℃, the flow rate was 1.0 mL/min, and the detection wavelength was 210 nm. The results of the methodological evaluation show that the precision RSD of 10 quaternary ammonium salts is less than 6%. The 10 quaternary ammonium salts show good linear relationship in the mass concentration range of 0.1-500 mg/L, with correlation coefficients of 0.999 4-0.999 8 and detection limits of 0.03-0.09 mg/L. The average recovery of 10 quaternary ammonium salts ranges from 96.80% to 105.25%, and the RSD ranges from 0.74% to 5.45%. Using this method, benzalkonium chloride （128.09 mg/kg）, dequalinium chloride （329.13 mg/kg） and cetylpyridinium chloride （231.04 mg/kg） are detected in three toothpastes, respectively. This method has good separation effect and high precision, and can be used for the detection of quaternary ammonium salts in oral care toothpastes.

Key words: high performance liquid chromatography, oral care toothpaste, simultaneous determination, quaternary ammonium salts, bactericide