ACS: Best practices to simplify environmental sample analysis by ICP-MS

Importance of the Topic

Environmental elemental analysis by ICP-MS is critical for ensuring compliance with drinking water, wastewater, soil, and industrial waste regulations worldwide. Reliable, trace and ultra-trace level detection of metals safeguards public health and supports environmental monitoring, remediation, and industrial discharge control.

Objectives and Study Overview

This document reviews best practices across the environmental sample analysis workflow using ICP-MS. It addresses sample and standard preparation, instrument innovations, optimization routines, and troubleshooting strategies. The goal is to streamline analysis, improve data quality, and reduce turnaround times.

Methodology and Instrumentation

Sample and Standard Preparation

• Use high-purity, traceable stock standards and ASTM Type I water.
• Employ plastic labware (PTFE, PFA, PP) and mechanical pipettes to minimize contamination.
• Calibrate and verify balances and pipettes regularly.

Digestion Techniques

• Hot plate and hot block acid digestion: straightforward but time-consuming and prone to contamination.
• Microwave-assisted acid digestion (EPA Method 3051a): reduces digestion time from hours to minutes and lowers reagent use.

Sample Introduction and Automation

• Cyclonic spray chambers, concentric glass or PFA nebulizers matched to matrix and flow rate.
• Autosamplers with discrete sampling valves (FAST) to reduce uptake and rinse times.
• Autodilution systems (prepFAST) for inline dilutions, internal standard addition, and autocalibration.

ICP-MS Instrument Innovations

• Thermo Scientific iCAP RQ ICP-MS: robust vertical analyzer, quick-connect sample introduction, argon gas dilution for high matrix tolerance.
• QCell™ Collision/Reaction Cell technology using He KED and Low Mass Cutoff for polyatomic interference removal.
• Triple quadrupole ICP-MS (iCAP TQ): tandem Q-cell with reactive gases (O₂) for mass shift and on-mass modes to eliminate isobaric and doubly charged interferences.
• Software Qtegra™ ISDS with Reaction Finder to guide mode selection and streamline method development.

Results and Discussion

Advanced CRC (KED+LMCO) reduced background equivalent concentrations (BECs) for As from >3700 ppt to <3 ppt and improved detection limits by over 1,000×. Triple quad with oxygen mass shift achieved sub-ppt detection levels. Autodilution and microwave digestion slashed sample prep and analysis times while maintaining accuracy within method requirements.

Benefits and Practical Applications

• Enhanced throughput: microwave digestion and automated sample handling reduce total analysis time.
• Improved robustness: argon dilution and specialized torches/nebulizers support high-TDS samples (wastewater, seawater).
• Superior data quality: comprehensive interference removal and inline QC ensure reliable trace-level measurements.
• Regulatory compliance: built-in method templates and QC protocols for EPA methods (200.8, 6020B, UCMR).

Future Trends and Potential Applications

Emerging directions include further integration of hyphenated techniques (IC-ICP-MS), AI-driven instrument diagnostics, lab-wide automation for sample logistics, portable ICP-MS platforms for field analysis, and advanced data analytics to enhance decision-making in environmental monitoring.

Conclusion

By adopting optimized sample prep, automation, instrument enhancements, and smart software, laboratories can achieve faster, more reliable, and cost-effective ICP-MS environmental analyses. These improvements support stringent regulatory requirements and advance environmental protection efforts.

Reference

Jeff Bown. "Best practices to simplify environmental sample analysis by ICP-MS." Thermo Fisher Scientific, August 2022.