ANALYSIS OF PESTICIDE RESIDUES IN DRINKING WATER AS PER BUREAU OF INDIAN STANDARDS USING THE AGILENT 7000 GC/MS/MS WITH PESTICIDES ANALYZER

Importance of the Topic

The monitoring of pesticide residues in drinking water is critical for public health and environmental protection. Regulatory limits for trace contaminants are increasingly stringent, requiring sensitive and reliable analytical techniques. The development of robust methods to detect sub-part-per-billion levels of multiple pesticide classes ensures compliance with standards and safeguards water quality.

Objectives and Study Overview

This work presents a validated protocol, following Bureau of Indian Standards (BIS) guidelines, for quantifying 28 pesticides in drinking and surface water. The goals were to achieve low detection limits (5 ng/L), high accuracy and precision, and efficient routine operation using gas chromatography-tandem mass spectrometry (GC/MS/MS).

Methodology and Instrumentation

A simple liquid–liquid extraction (LLE) concentrates analytes from 1 L water samples into ethyl acetate. Calibration covers 10–100 ng/L spiked levels, with matrix-matched standards to assess recovery. Instrumentation details:

• Gas Chromatograph: Agilent 7890B with multimode inlet in programmed temperature vaporization (PTV) solvent vent mode.
• Mass Spectrometer: Agilent 7000C triple quadrupole operating in electron ionization multiple reaction monitoring (EI-MRM) mode.
• Column Configuration: Two HP-5ms columns (15 m × 0.25 mm × 0.25 µm) with retention time locking and concurrent backflushing to remove nonvolatile matrix components.
• Carrier Gas: Helium at 1.5 mL/min; backflush pressure adjustments to protect the source.

Main Results and Discussion

All pesticides exhibited linear responses with correlation coefficients above 0.995 in solvent and matrix. Method detection limits reached 5 ng/L and quantitation limits 10 ng/L. Recoveries ranged between 88% and 99% with relative standard deviations below 8% (n=7) across intra- and inter-day studies. Backflushing minimized carryover and source contamination, maintaining consistent sensitivity over repeated injections.

Benefits and Practical Applications

The method offers:

• High sensitivity for trace-level monitoring in regulatory laboratories.
• Rapid analysis cycle (40 min) with reduced downtime due to backflush.
• Simple sample preparation with common solvents and equipment.
• Applicability to diverse water matrices, including drinking, packaged, and surface water.

Future Trends and Potential Applications

Emerging directions include coupling with automated online extraction to increase throughput, miniaturized sample handling to reduce solvent use, and integration of high-resolution mass spectrometry for non-target screening. Digital data workflows and real-time monitoring sensors may further streamline environmental compliance.

Conclusion

This GC/MS/MS approach meets stringent BIS requirements for pesticide residue analysis in drinking water. It combines high sensitivity, strong reproducibility, and operational efficiency, making it well suited for routine regulatory and quality control laboratories.

References

1. Meng C-K., Improving productivity and extending column life with backflush, Agilent Technologies, 2006.
2. Maštovská K., Wylie P.L., Evaluation of column backflushing in GC-MS/MS pesticide analysis, J. Chromatogr. A, 2012.
3. Agilent Technologies, Pesticide Analysis Reference Guide, 2013.
4. EFSA, Peer review of pesticide risk assessment, EFSA Journal, 2010.
5. Bureau of Indian Standards, IS 10500: Drinking Water, 2012.
6. SANCO/12571/2013, Guidance document on validation for pesticide residues, European Commission, 2013.