RoHS/ELV Directives - Measurement of Heavy Metals Using ICP-MS

Importance of the Topic

The restriction of hazardous substances in electrical, electronic, and automotive products is critical for environmental protection, human health, and regulatory compliance. Accurate determination of trace levels of cadmium, lead, mercury, and hexavalent chromium in complex matrices ensures manufacturers meet EU RoHS and ELV thresholds and supports global market acceptance.

Objectives and Overview of the Study

This application note outlines the development and validation of a robust inductively coupled plasma mass spectrometry (ICP-MS) method using an Agilent 7500c with an Octopole Reaction System (ORS) for the simultaneous determination of RoHS-regulated heavy metals. The study compares ICP-MS performance against energy dispersive X-ray fluorescence (EDXRF) and establishes detection limits, accuracy, and precision in various polymeric and high-matrix samples.

Methodology and Used Instrumentation

The approach integrates standardized sample digestion and collision/reaction cell ICP-MS analysis:

• Sample Preparation: Microwave-assisted acid digestion following US EPA SW-846 Method 3052 for cadmium, lead, mercury, and total chromium screening; alkaline extraction per EPA 3060A/7196A for hexavalent chromium when required.
• ICP-MS Analysis: Agilent 7500c ORS operating with hydrogen in the cell to reduce polyatomic interferences. Key parameters include RF power 1 600 W, carrier gas 1.2 L/min, helium collision gas 4.5 mL/min, and internal standards selected by mass proximity and ionization potential (e.g., In, Y, Ga, Tl).
• Quality Control: Calibration with multi-element standards, Grubbs’ test for outliers, and internal standard corrections for matrix suppression.

Main Results and Discussion

Validation using a certified polyethylene reference (CBR-680) yielded recoveries of 98–101% for cadmium, with coefficients of variation below 3.2%. Participation in an international proficiency test (IIS04P02) showed z-scores within ±1.48 for cadmium and lead across PVC samples, confirming method accuracy. The ORS collision cell in helium mode effectively minimized spectral overlaps in high-matrix materials, allowing direct analysis without extensive pretreatment. A comparative study demonstrated EDXRF overestimated lead in brominated flame-retardant plastics due to arsenic and bromine interferences, whereas ICP-MS provided accurate results at sub-10 mg/kg levels.

Benefits and Practical Applications of the Method

The multi-element capability of ICP-MS enables simultaneous quantification of RoHS metals and additional impurities such as antimony, arsenic, beryllium, and selenium. High sensitivity reduces sample size and acid consumption, accelerating throughput and lowering waste. The technique supports isotope dilution mass spectrometry for ultimate accuracy, making it suitable for compliance testing, quality assurance in manufacturing, and investigation of contaminant origins.

Future Trends and Application Possibilities

Continued adoption of ICP-MS in international standardization (IEC TC111) will expand its role in RoHS/ELV compliance and green procurement guidelines. Advances in reaction cell chemistry, automation, and real-time monitoring promise further improvements in matrix tolerance and detection limits. Integration with isotope dilution and advanced data analytics will enhance traceability, measurement uncertainty assessment, and process control across industries.

Conclusion

The validated Agilent 7500c ORS ICP-MS method delivers reliable, sensitive, and efficient measurement of heavy metals regulated by RoHS and ELV directives. Accredited under ISO/IEC 17025 and supported by ISO 9001 management, the approach meets international requirements and offers a streamlined solution for high-throughput compliance testing.

Reference

1. BS EN1122:2001 Plastics – Determination of Cadmium – Wet Decomposition Method.
2. US EPA SW-846 Method 3052: Microwave Assisted Acid Digestion of Siliceous and Organically Based Matrices.
3. Institute for Interlaboratory Studies Proficiency Test IIS04P02: Cadmium and Lead in Plastics, 2004.
4. JEITA JGPSSI Green Procurement Guidelines: Joint Industry Guideline on Material Declaration.