Simultaneous Analysis of Chlorate, Bromate, Perchlorate and Chlorite in Tap Water Using a Triple Quadrupole LC/MS/MS

Importance of the Topic

Chlorate and bromate are regulated disinfection by-products in drinking water due to potential health risks. Simultaneous determination of these and related oxyhalides enhances monitoring efficiency and supports compliance with water quality standards.

Objectives and Study Overview

This study applies the Annex 18-2 method specified by Japan’s Ministry of Health, Labour and Welfare to develop a rapid LC–MS/MS protocol. Four oxyhalide anions—chlorate, bromate, perchlorate and chlorite—are targeted for simultaneous quantification in tap water.

Methodology and Instrumentation

A Shimadzu LCMS-8060 triple quadrupole system with negative-ion ESI was employed. Separation used an Acclaim® Trinity P1 column (100×3.0 mm, 3 µm) with a gradient of 200 mmol/L ammonium acetate (0.5% acetic acid) and acetonitrile. Key MS parameters:

• Flow rate: 0.4 mL/min; column temperature: 35 °C; injection: 1 µL
• ESI negative at −1.0 kV; DL 150 °C; heater and interface at 400 °C
• Nebulizing, drying and heating gas flows: 2, 5 and 20 L/min
• MRM transitions with quantifier and qualifier ions for each analyte

Key Results and Discussion

MRM chromatograms demonstrated detection limits down to 1/10 of regulatory values. Calibration curves showed excellent linearity (R2 > 0.999) across relevant concentration ranges. Spike-and-recovery tests in tap water yielded recoveries of 96–120% with RSDs below 7%, confirming accuracy and precision.

Benefits and Practical Applications

The method enables rapid multi-analyte screening in water quality control laboratories. Simultaneous analysis reduces runtime and resource consumption while ensuring compliance with regulatory frameworks.

Future Trends and Applications

Emerging developments may include integration with high-resolution mass spectrometry for unknown by-product profiling, automated sample preparation, on-site portable LC–MS systems, and expanded monitoring of additional oxyhalides or emerging contaminants.

Conclusion

The validated LC-MS/MS method meets Japanese regulatory criteria for chlorate, bromate, perchlorate and chlorite analysis. It offers robust sensitivity, reproducibility and efficiency for routine drinking water surveillance.

Reference

Shimadzu Application No. C221 News, First Edition July 2020