A colorimetric assay for the determination of polyhexamethylene biguanide in pool and spa water using nickel-nioxime

摘要

A novel nickel-nioxime analytical method to measure polyhexamethylene biguanide (PHMB) in swimming pools and spas was developed.This method utilizes nickel(II) chloride and 1,2-cyclohexanedionedioxime (nioxime) chemistry.In the method,nickel ions bind and neutralize PHMB in the solution.Excess,un-reacted nickel ions react with nioxime and the resulting colored solution is measured at 550 nm using a colorimetric assay.Currently,the colorimetric method to measure PHMB uses bromophenol blue (BPB).However,high levels of quaternary ammonium based algaecides and surfactant based products interfere with this colorimetric method.A time-consuming and expensive high-performance liquid chromatographic (HPLC) analysis can be used for samples with high levels of quaternary ammonium based algaecides or surfactants.The proposed nickel-nioxime detection method achieves comparable PHMB results to HPLC in about 5 min and is a very economical and simple method to perform.