Multielement analysis of drinking water samples as per regulations from the Bureau of Indian Standards using ICP-MS

Importance of the Topic

Ensuring drinking water meets regulatory contaminant limits is essential to protect human health and the environment. Inductively coupled plasma mass spectrometry offers high sensitivity for trace analysis, meeting stringent Indian Standards such as IS 10500, IS 13428 and IS 14543.

Objectives and Study Overview

This study demonstrates the use of the Thermo Scientific iCAP MSX ICP-MS with argon gas dilution to perform multi element analysis on surface water, groundwater and drinking water. The goal was to assess the system’s performance in terms of sensitivity, accuracy, robustness, and regulatory compliance.

Methodology and Instrumentation

The iCAP MSX ICP-MS was equipped with:

• Argon gas dilution at level 5 for on line fivefold sample dilution
• QCell collision/reaction cell in helium KED mode to remove polyatomic interferences
• iSC-65 autosampler for automated sample handling
• Quartz torch, MX series nebulizer, cyclonic spray chamber at 2.7 °C
• Operating conditions: RF power 1550 W, cool gas 14 L/min, nebulizer flow 0.45 L/min, sampling depth 8 mm, dwell time 50 ms and three replicates per isotope

Calibration was performed using five gravimetrically prepared multi element standards in 2% HNO3 and 0.5% HCl. Two certified reference materials (LGC-6026 Hard drinking water – metals and SLRS-6 River water) and a continuous internal standard mixture (Sc, Ge, Rh, In, Ir, Tl) were used to monitor accuracy and instrument stability. Data acquisition and QC were managed by Qtegra ISDS software and the HAWK maintenance assistant.

Main Results and Discussion

• Linearity: Correlation coefficients exceeding 0.999 for all elements
• Detection limits: Sub µg/L to low µg/L across the mass range, meeting regulatory requirements
• Accuracy: Recoveries for CRMs ranged between 80 % and 120 %
• Robustness: Over a 12 hour sequence with more than 250 samples, internal standard recoveries remained within 80–120 % and QC checks every 15 samples yielded 90–110 % recoveries
• Sample results: Concentrations of major and trace elements in unknown water samples were consistently below the maximum contaminant levels specified by Indian regulations

Benefits and Practical Applications

• Automated on line dilution reduces labor, cost and contamination risk
• High dynamic range allows simultaneous measurement of major and trace elements in a single run
• Collision cell KED mode provides effective interference removal without mode switching
• Integrated software solutions streamline QC, data processing and maintenance scheduling
• System robustness supports high sample throughput in routine water quality monitoring

Future Trends and Applications

• Further automation and integration with laboratory information management systems
• Advanced interference correction strategies and reaction gas options for challenging matrices
• Expansion into speciation analysis, nanoparticle detection and isotope ratio applications
• Miniaturized and field deployable ICP MS systems for on site water monitoring

Conclusion

The Thermo Scientific iCAP MSX ICP-MS combined with argon gas dilution and robust collision cell technology provides a reliable, sensitive and high throughput solution for multi element analysis of drinking and environmental waters. It meets Indian regulatory standards, ensures data quality through integrated QC, and supports routine laboratory workflows with minimal sample preparation.

References

• IS 10500:2012 Drinking water Specification
• IS 13428:2005 Packaged Natural Mineral Water Specification
• IS 14543:2004 Packaged Drinking Water Specification