The European Union (EU) has introduced legislation on electrical and electronic equipment in relation to its composition and the levels to which it should be recycled. This legislation has its origin in the EU Directives relating to Waste Electrical and Electronic Equipment (WEEE) and to the Restriction of Hazardous Substances (RoHS) in new products. Manufacturers will need to ensure that their products (and their components) comply in order to sell in the European market. If they do not comply, they will need to redesign their products.

Another EU directive, End-of Life Vehicles (ELV), aims to reduce, or prevent, the amount of waste produced from ELVs and increase the recovery and recycling of materials or components. The ELV Directive banned lead, cadmium, mercury and hexavalent chromium from products, with some exemptions, from 1 July 2002. The RoHS Directive will ban the placing on the EU market of new electrical and electronic equipment containing more than agreed levels of lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyl (PBB) and polybrominated diphenyl ether (PBDE) flame retardants from 1 July 2006. The limits for these substances required by both directives are given in Table 1.

Table 1. Limits for RoHS and ELV directives.

Element


Limit

Pb, Hg, Cr6+, PBB*, PBDE*


0.1wt%

Cd


0.01wt%

Note: *only for RoHS directive
Directives on Materials Recycling in the Rest of the World

In other parts of the world similar directives are being introduced including electronic waste recycling legislation in the USA, often referred to as California RoHS, and the adoption of RoHS in China. Given the rigorous demands of such legislation, X-ray fluorescence spectroscopy (XRF) has emerged as the optimal solution for elemental analysis of heavy metals in a wide variety of materials, including brass.
Analysis of Cadmium and Lead in Brass

This note demonstrates the capability of the Epsilon 5 energy-dispersive XRF spectrometer for the analysis of Cd and Pb in bulk brass samples. In addition, results are presented for the analysis of Cd in brass samples of various shapes and sizes, since such samples are likely to be encountered when analyzing product sub-assemblies.
Measurement Criteria

Measurement criteria The application was set up and calibrated using five brass certified reference materials (MH1 to 5) from MBH Analytical Ltd (UK). The measurement conditions are given in Table 2.

Table 2. Analytical parameters used for the application set-up. *This is the maximum current; for each measurement the current is adjusted to obtain maximum 50% detector dead-time.

Element


Secondary Target


Measurement live time (s)


kV


mA*

Cd


CsI


300


100


6

Pb


Zr


300


100


6
Accuracy

Figures 1 and 2 show calibration curves for Cd and Pb in brass samples and a summary of the calibration data is given in Table 3. These data show a good correlation between the certified concentrations and the measured intensities. The calibration RMS indicates the accuracy of the method. It is a statistical comparison (1 sigma) of the certified chemical concentrations of the standards with the concentrations calculated by the regression in the calibration procedure. In addition, a certified reference material (BNF C48.06) was analyzed as an unknown sample. A comparison of the certified and measured values for Cd and Pb is shown in Table 4.