A selected ion monitoring assay for chlorhexidine in medical waste water

Abstract

We have developed a method for determination of chlorhexidine, a disinfectant, in medical waste water by selected ion monitoring (SIM). Our method consists of the following procedures. (1) Chlorhexidine in the medical waste water was extracted and purified by an Extrelut® column with ethyl acetate. (2) The eluted chlorhexidine was converted to a triazine derivative with trifluoroacetic anhydride. (3) The triazine derivative was subjected to on-column methylation on a gas chromatographic column. (4) Finally, the triazine N-methyl derivative of chlorhexidine was identified and determined by SIM. Recoveries of the compound added to medical waste water were about 90% in amounts ranging from 1 to 10 μg. In the waste water from our medical waste water treatment plant, chlorhexidine concentrations were found to be 0.085–1.94 mg I−1. The present method is superior to the pre-existing ones in its quick separation, specificity and sensitivity.