Rapid determination of nine haloacetic acids in water using ultra-performance liquid chromatography-tandem mass spectrometry in multiple reactions monitoring mode

Abstract

A simple and rapid detection method for nine haloacetic acids (HAAs) in water has been developed using ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) in multiple reactions monitoring (MRM) mode. Addition of a small amount of formic acid (FA) as a modifier for the methanol–water eluent was found to be critical for separation of the analytes with smaller molecular size (i.e. the mono and di-haloacetic acids). Without the need of sample preconcentration, very low limits of detection (LODs) for the nine HAAs were achieved (0.06–0.16 μg L⁻¹). The linear calibration range extended from 0.5 up to 100 μg L⁻¹ (R² = 0.9993–0.9997, n = 6). The water matrix effect has been examined, and seems to be related to the ions in real water samples. Interestingly, an adjustment of the pH of the tap water samples to an acidic value of 3 or below basically eliminated the matrix effect. The method has been tested using tap water samples sourced from both surface water (total dissolved solid (TDS): 145 ± 3 mg L⁻¹) and groundwater (TDS: 362 ± 1 mg L⁻¹) with high precision and recovery. A separation mechanism of the ionic analytes using a reversed phase liquid chromatographic column (HSS T3) possessing a hydrophilic affinity has been proposed and discussed.