Analysis of plastics and polymers for RoHS/WEE compliance by EDXRF

Význam tématu

Plastics and polymers often contain restricted heavy metals and flame retardants which pose environmental and health risks upon disposal or recycling. Compliance with RoHS and WEEE directives is critical to minimize pollutant release and protect public health.

Cíle a přehled studie / článku

This application note presents a protocol using the Thermo Scientific ARL QUANT'X EDXRF spectrometer to quantify lead, cadmium, mercury, hexavalent chromium and bromine in polyethylene and polyvinylchloride matrices in order to ensure RoHS/WEEE compliance.

Použitá instrumentace

The ARL QUANT'X is a benchtop energy dispersive X-ray fluorescence system equipped with a 50 W X-ray tube (Ag or Rh anode) and a large-area silicon drift detector with a beryllium or graphene window, enabling detection from Na (Z=11) down to C (Z=6). Analytical software supports empirical, theoretical and standardless calibrations.

Použitá metodika

No sample pretreatment is required. Calibration utilizes PE and PVC polymer standards at blank, mid (500 ppm Cr, Br, 50 ppm Cd, 500 ppm Hg, Pb) and high (1000 ppm Cr, Br, 100 ppm Cd, 1000 ppm Hg, Pb) levels. Three excitation conditions optimize element excitation: Mid Za (16 kV, Thin Ag filter) for Cr; Mid Zc (30 kV, Thick Ag filter) for Br, Hg, Pb; and High Zb (50 kV, Thick Cu filter) for Cd. Each measurement is performed in air for 100 s live time per condition with automatic current adjustment (50% dead time). Spectral deconvolution corrects for overlaps. Limits of detection are determined via ten replicate analyses of blank samples and calculating 3σ.

Hlavní výsledky a diskuse

Calibration curves exhibit linear responses across the tested ranges in both PE and PVC matrices. Detection limits in PE are approximately 0.4 ppm for Cr and Pb, 0.2 ppm for Br, 0.3 ppm for Hg and 3.1 ppm for Cd. Slightly higher LODs are observed in PVC. High spectral resolution and count rates ensure accurate quantification even at low ppm levels.

Přínosy a praktické využití metody

The ARL QUANT'X EDXRF provides a fast, non-destructive and cost-effective solution for routine screening of restricted substances in plastics. Minimal sample preparation, air-based analysis and short measurement times support high sample throughput in QC, recycling, and regulatory laboratories.

Budoucí trendy a možnosti využití

Future developments may include automated sample handling, expansion of speciation capabilities for hexavalent chromium and brominated flame retardants, integration with data management systems and coupling with complementary techniques for compound-specific analysis.

Závěr

The ARL QUANT'X EDXRF spectrometer demonstrates excellent performance for the quantification of RoHS-regulated elements in polymer matrices, meeting sensitivity requirements while offering simplicity and efficiency for compliance workflows.

Reference

1. Lemberge P. Analysis of plastics and polymers for RoHS/WEEE compliance by EDXRF using ARL QUANT'X Energy Dispersive X-Ray Fluorescence Spectrometer. Thermo Fisher Scientific Application Note AN41969, 2024.
2. ASTM International. ASTM F2617-08: Standard Test Method for Identification and Quantification of Cr, Br, Cd, Hg, and Pb in Polymeric Material Using Energy Dispersive X-Ray Spectrometry, 2008.