Simultaneous LC-MS/MS Analysis of Haloacetic Acids, Bromate, Chlorate, and Dalapon in Water Samples

Significance of the Topic

The presence of disinfection by ‑ products such as haloacetic acids, bromate and chlorate in drinking water poses known health risks including carcinogenicity. Monitoring these compounds alongside the herbicide Dalapon is critical for regulatory compliance and public health protection. A simultaneous analytical approach reduces analysis time and resource consumption while ensuring accurate quantification of multiple contaminants in diverse water matrices.

Objectives and Study Overview

This study aimed to develop and validate a single-injection liquid chromatography tandem mass spectrometry method for the simultaneous determination of nine haloacetic acids (HAA9), bromate, chlorate and Dalapon in various water samples. Key goals included achieving low detection limits, robust calibration, and consistent recoveries across pure water, fortified blanks and natural water samples.

Methodology

The method employed reverse-phase chromatography with a 20-minute gradient using formic acid in water and methanol. Samples were spiked with stable isotope internal standards at fixed concentrations to correct for matrix effects. Calibration curves covering 0.05 to 100 µg/L were generated in LC-MS grade water using a 1/C2 weighting, yielding r2 values above 0.99. A laboratory fortified blank and a synthetic sample matrix mimicking drinking water ionic strength were used to evaluate method accuracy and precision. Six real water samples from tap water, river and stream sources were analyzed in triplicate.

Used Instrumentation

• Shimadzu LC-30 Nexera high-performance liquid chromatography system
• Shimadzu LCMS-8060NX triple quadrupole mass spectrometer with electrospray ionization in negative mode
• Capcell Pak C18 MGIII column (150 mm × 3 mm, 3 µm) with 25 °C column oven
• MRM transitions optimized for each analyte and internal standard

Main Results and Discussion

Calibration achieved excellent linearity for all targets (r2 > 0.99) with accuracy between 80 and 120 across the calibration range. Recoveries in the fortified blank at 5 and 100 µg/L ranged from 80 to 120 with relative standard deviations under 15%. In the synthetic sample matrix, early-eluting haloacetic acids exhibited slight peak broadening, while later eluters remained unaffected. Real-world water analysis revealed that chlorate was frequently detected in tap water up to 400 µg/L. Select haloacetic acids such as dichloroacetic acid, bromochloroacetic acid and tribromoacetic acid were detected at low microgram per liter levels in some tap waters. Dalapon appeared in specific tap samples at concentrations up to 3 µg/L. No compounds were detected in river and stream samples above the reporting limits.

Benefits and Practical Applications

• Consolidates multiple regulated and emerging contaminants into a single 20-minute run
• Reduces solvent use and sample handling compared to multiple separate assays
• Delivers high sensitivity and reproducibility suitable for routine compliance monitoring
• Applicable to drinking water quality control, environmental surveillance and research studies on disinfection by-products

Future Trends and Applications

Advances may include coupling online solid-phase extraction for enhanced throughput, adoption of high-resolution mass spectrometry to identify novel disinfection by-products and integration with automated data processing pipelines. Miniaturized flow systems and ambient ionization approaches could further streamline field-deployable water analysis platforms.

Conclusion

The developed LC-MS/MS method on the LCMS-8060NX provides a rapid, sensitive and reliable tool for simultaneous determination of haloacetic acids, bromate, chlorate and Dalapon in various water matrices. The approach meets regulatory performance criteria and offers practical advantages in routine water quality monitoring.

References

1. EPA Envirofacts ICR database entry on haloacetic acids accessed June 17, 2021
2. EPA Method 557 Determination of Haloacetic Acids, Bromate, and Dalapon in Drinking Water by IC-ESI-MS/MS September 2009