Determining haloacetic acids in drinking water by one-pump column-switching ion chromatography: An online and cost-effective tool for matrix removal and sample enrichment

Abstract

Haloacetic acids (HAAs) are a group of disinfection byproducts ubiquitously found in disinfected drinking water and they are currently regulated by some governments. Conventional HAAs analytic methods employ either gas chromatography (GC), two-dimensional ion chromatography (2D-IC), or ion chromatography with electrospray ionization tandem mass spectrometry (IC-ESI-MS/MS) to reduce the effect of interfering compounds and enhance detection resolution; however, they are either laborious in sample preparation procedures or too expensive to be used by common laboratories. To bypass these problems, this study proposes to analyze HAAs by employing a one-pump column-switching ion chromatography (OPCS-IC) that allows direct sample injection without requiring extraction and derivatization pretreatments. Unlike 2D-IC method, which uses two pumps and two parallel sets of IC columns, this method applies only one pump and one column. The tailored OPCS-IC removes coexisting anions from water and enriches HAAs simultaneously, thereby distinguishing HAAs from interfering anions and magnifying the signals of HAAs. For example, when HAAs were enriched by five times, the coexisting F−, Cl−, Br−, NO3–, and SO42− were removed by 62.4%, 93.9%, 99.7%, 99.9%, and 98.9%, respectively. Meanwhile, the recoveries of HAAs dosed into real samples ranged from 84% to 102%, similar to those obtained from conventional GC method, meaning that the convenience of this method did not compromise its performance. The study hence proves an easy-to-use and relatively cheaper method for measuring HAAs in drinking water.