Simultaneous analysis of residual contaminants in drinking water using Programmed Temperature Vaporization (PTV) for Large Volume Injection (LVI) and GC-MS/MS

Importance of the Topic

Contamination of drinking water by persistent organic pollutants such as PAHs, PCBs and pesticides poses serious public health and environmental risks. Efficient monitoring of trace-level residues is crucial to ensure safety and regulatory compliance. The described method addresses limitations of traditional extraction techniques by reducing solvent use, minimizing sample handling and enhancing reproducibility.

Objectives and Study Overview

The primary goal was to develop and validate a single GC-MS/MS method using programmed temperature vaporization (PTV) for large volume injection (LVI) capable of simultaneously quantifying over 60 priority contaminants in drinking water at sub-ppb levels. Validation focused on sensitivity, accuracy, precision and linearity following SANTE guidelines.

Methodology and Instrumentation Used

An optimized sample preparation protocol employed 30 mL water samples extracted with 3 mL dichloromethane and sodium chloride. The extraction inherently concentrated analytes tenfold, eliminating separate evaporation steps. A 50 µL injection in PTV split mode introduced analytes into the GC-MS/MS. Chromatographic separation was achieved on a dimethylpolysiloxane column and detection performed on a triple quadrupole mass spectrometer in MRM mode. Matrix-matched calibration and spiked recoveries assessed method performance.

Main Results and Discussion

The method achieved limits of quantification of 0.005 ppb for 36 compounds and 0.05 ppb for 22 compounds, with linear dynamic ranges from 0.025 to 10 ppb (r2 ≥ 0.97). Recoveries fell within 80–120 % and reproducibility (% RSD) remained below 20 % at LOQ levels. The absence of a final concentration step reduced variability and sample preparation time. These results demonstrate high sensitivity and robustness for routine monitoring.

Benefits and Practical Applications

• Minimal solvent and sample volume requirements
• Rapid, single-method analysis of multiple pollutant classes
• High throughput capability with large volume injection
• Compliance with international validation criteria

Future Trends and Potential Applications

Advances may include integration of automated extraction, coupling with high-resolution mass spectrometry for non-target screening and adaptation to broader environmental or food matrices. Miniaturized PTV systems and enhanced data processing pipelines will further streamline monitoring workflows.

Conclusion

The presented PTV-LVI GC-MS/MS approach offers a sensitive, efficient and reliable solution for simultaneous analysis of diverse residual contaminants in drinking water. Its reduced sample preparation burden and strong validation performance make it suitable for routine environmental surveillance and regulatory compliance.

Instrumentation Employed

• Shimadzu GCMS-TQ8040 NX triple quadrupole mass spectrometer
• PTV large volume injection system (AOCTM-20i plus s)
• SH-I-5Sil MS capillary column (30 m × 0.25 mm, 0.25 μm film)

References

• Guidance document on analytical quality control and method validation procedures for pesticide residues and analysis in food and feed SANTE/11312/2021