Rapid Determination of Nine Haloacetic Acids in Wastewater Effluents Using Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry

Abstract

A rapid detection method for nine haloacetic acids (HAAs) in wastewater effluent has been developed using ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS). A reverse solid-phase extraction (RSPE) protocol was developed for removing dissolved organic matter (DOM) in effluent samples to minimize its adverse effects. Three cartridges were selected for evaluation of the RSPE pretreatment effectiveness. Fluorescence excitation-emission matrix (EEM) and ultraviolet-visible spectrophotometry were employed to assess the DOM removal efficiencies. The A C₁₈ cartridge was found to exhibit the best performance. The matrix effects of the RSPE-treated effluent samples on separation were eliminated by pH adjustment down to 2.5 and a complete LC separation of all the nine HAAs was achieved. The signal suppression was negligible after up to 400 injections of such treated wastewater effluent samples. The limits of detection (LODs) and limits of quantitation (LOQs) for the nine HAAs were in the range of 0.08–0.25 and 0.24–0.75 µg L⁻¹, respectively; the linear calibration ranged from 0.5 or 1 up to 100 µg L⁻¹ (r² = 0.9993 – 0.9999, n = 8). The method recoveries of spiked wastewater effluents for all the analytes at concentrations of 2.5 and 10 µg L⁻¹ were in the range of 89.0–104.2%; the precision values (as intra- and inter-day relative standard deviation, RSD) were in the range of 1.4–5.6%. The proposed method was used to determine the HAAs in chlorinated effluents from ten wastewater treatment plants.

Keywords:

• Disinfection byproducts
• Haloacetic acids
• UPLC-MS/MS
• Wastewater effluents

Acknowledgments

The laboratory instrumentation was supported by the “Program for Changjiang Scholars and Innovative Research Team in University” (PCSIRT) (Grant No. IRT0853). The authors wish to express their thanks for the financial support from the NSFC (No. 50830303) and Scientific Research Foundation of Xi'an University of Architecture and Technology (DB03087).

Notes

Note: TDS, total dissolved solid; DOC, dissolved organic carbon; COD, chemical oxygen demand; TN, total nitrogen; TP, total phosphorus.

^a The 24th injection of filtered spiked blank matrix samples (without postcolumn splitting).

The 24th injection of RSPE-treated spiked blank matrix samples (without postcolumn splitting).

^c The 400th injection of RSPE-treated spiked blank matrix samples (with postcolumn splitting).

Note: nd, not detected.