Simultaneous determination of iodinated haloacetic acids and aromatic iodinated disinfection byproducts in waters with a new SPE-HPLC-MS/MS method

Abstract

Iodinated disinfection byproducts (DBPs) are an emerging category of halogenated DBPs in concern due to their high toxicity. Among them, polar iodinated DBPs, mainly including iodinated haloacetic acids (HAAs) and aromatic iodinated DBPs, were reported to be especially toxic. Thus, simultaneous determination of these polar iodinated DBPs in disinfected waters is of great significance for DBP studies. In this study, it was found that traditional liquid-liquid extraction, which was adopted for the determination of polar iodinated DBPs, was actually not suitable for the determination of monoiodoacetic acid (MIAA) and diiodoacetic acid (DIAA) due to the low recoveries, and thus a new SPE-HPLC-MS/MS method was developed for the simultaneous determination of iodinated HAAs and aromatic iodinated DBPs. The parameters for SPE pretreatment were optimized, including SPE cartridge, eluent volume, formic acid content in eluent, and sample pH before SPE. The new method was demonstrated to be sensitive and accurate with detection limits of 0.15, 0.04, 0.03, 0.02, 0.06, and 0.06 ng/L, quantitation limits of 0.48, 0.13, 0.10, 0.06, 0.19, and 0.19 ng/L, and precision of 8.3%, 6.0%, 12.3%, 8.8%, 11.4%, and 15.6% for MIAA, DIAA, 3,5-diiodo-4-hydroxybenzaldehyde, 3,5-diiodosalicylic acid, 2,6-diiodo-4-nitrophenol and 2,4,6-triiodophenol, respectively. The recoveries of these six polar iodinated DBPs were all in the range of 70–110%. The new method was applied to the determination of iodinated HAAs and aromatic iodinated DBPs in nine tap water samples, and they were detected with concentrations ranging from 0.03 to 3.97 ng/L, among which MIAA was detected in all the samples with the highest concentrations.