The Use of Accurate Mass Peak Filters to Detect and Identify New Disinfection Byproducts in Swimming Pools and Spas

Significance of the Topic

Swimming pools and spas are treated with disinfectants such as chlorine and bromine to ensure microbial safety, but these treatments can generate a variety of disinfection byproducts (DBPs) with potential health risks. Identifying and characterizing these DBPs is critical for monitoring water quality and minimizing human exposure to unknown or toxic compounds.

Study Objectives and Overview

The main goal of this study was to apply accurate mass peak filters in combination with comprehensive two-dimensional gas chromatography and high-resolution time-of-flight mass spectrometry (GC×GC-HRTOFMS) to detect, classify, and tentatively identify new DBPs in swimming pool and spa waters. The workflow integrated automated peak finding, high-resolution deconvolution, and spectral peak filters targeting halogenated compound classes.

Methodology and Instrumentation

The analytical platform consisted of LECO’s GC×GC system coupled to a high-resolution TOF mass spectrometer (resolving power up to 50 000 FWHM) controlled by ChromTOF-HRT software. Samples (1 µL splitless injection) were analyzed on a primary Rtx-200 column and a secondary Rxi-5ms column, with temperature programming from 35 °C to 300 °C over 60 min. Mass spectra were acquired at up to 200 spectra/s, calibrated using perfluorotributylamine, and post-run mass accuracy was maintained below 0.5 ppm RMS.

Used Instrumentation

• GC×GC columns: 30 m×0.25 mm×0.25 µm (Rtx-200) and 0.6 m×0.25 mm×0.25 µm (Rxi-5ms)
• GC×GC modulator with 3 s period, secondary oven +5 °C offset
• LECO HRTOF mass spectrometer (RP 25 000 to 50 000 FWHM)
• ChromTOF-HRT software for acquisition, deconvolution, and accurate mass filtering

Main Results and Discussion

Automated high-resolution deconvolution detected over 10 000 chromatographic peaks in brominated pool samples, of which only ~3 % matched spectral libraries with similarity >850 and mass error ±2 ppm. Spectral peak filters designed for bromine and chlorine isotopic patterns isolated nearly 500 Br₂-containing features. Comparative classification tables showed that brominated DBPs increased significantly from raw and tap water to pool and spa water, while chlorinated species dominated chlorine-treated tap water. Accurate mass formula assignment and ChemSpider search enabled tentative identification of positional isomers for select high-intensity peaks.

Benefits and Practical Applications

Applying accurate mass peak filters with GC×GC-HRTOFMS enables:

• Comprehensive profiling of known and unknown DBPs in complex matrices
• High-throughput classification by halogen content and isotopic signatures
• Tentative identification of novel compounds for further toxicological assessment

Future Trends and Opportunities

Future developments may include integration of machine learning algorithms for pattern recognition, expansion of accurate mass filters to additional compound classes (e.g., nitrogenous DBPs), and coupling with online sample pre-concentration techniques. Enhanced spectral databases and predictive tools will support more confident identification and risk evaluation of emerging DBPs.

Conclusion

Accurate mass peak filtering combined with GC×GC-HRTOFMS provides a powerful strategy for detecting, classifying, and preliminarily identifying new disinfection byproducts in swimming pools and spas. This approach greatly expands the capability to monitor water treatment byproducts and supports informed decisions for public health protection.

References

1. Daiber EJ, Ravuri SA, Binkley J, Richardson SD. Progressive Increase in Disinfection Byproducts and Mutagenicity from Source to Tap to Swimming Pool and Spa Water: Impact of Human Inputs. Environ Sci Technol. 2016; DOI:10.1021/acs.est.6b00808.