Determination of 3 Homologues of Benzalkonium Chloride in Disinfection Products by Reversed Phase Liquid Chromatography with Diode Array Detection

At present, the standard method for detecting benzalkonium chloride only uses an average relative molecular weight (geramine) to represent two or several mixtures, which cannot distinguish several homologues of benzalkonium chloride. In order to determine benzalkonium chloride homologues, the study mentioned by the title was proposed. 1.000 0 g of disinfection product was taken, diluted with water to 10 mL, extracted for 5 min by ultrasound and settled. The solution was passed through 0.45 μm polysulfone ether aqueous phase filter membrane. Three homologues of benzalkonium chloride, dodecyl dimethyl benzyl ammonium chloride, tetradecyl dimethyl benzyl ammonium chloride, and hexadecyl dimethyl benzyl ammonium chloride, in the filtrate were separated on Agilent XDB-C₁₈ column (250 mm×4.6 mm, 5 μm), eluted isocratically with a miture of acetonitrile and 0.5 g·L^-1 ammonium acetate buffer solution (pH 5.0) containing 0.1% (volume fraction) triethylamine at volume ratio of 70\:30, and detected at 262 nm by a diode array detector. As shown by the results, the volume fraction of the sweeping agent triethylamine was reduced from 1% to 0.1%, avoiding the possible damage of the sweeping agent triethylamine to the chromatographic column and solving the problem of ghost peaks. Linear relationships between values of the corresponding peak area and mass concentration of three homologues of benzalkonium chloride were found in the range of 10-500 mg·L^-1, with detection limits (3S/N) of 1.1, 1.2, 1.5 mg·L^-1, respectively. Test for recovery was made by the standard addition method, giving the results in the range of 98.8%-105%, with RSDs (n=8) of the determined values less than 2.0%. This method was used for the analysis of actual disinfection products, with detection amounts in the range of 0.027%-44.60%, involving both trace and constant amounts.