Method of X-ray fluorescence analysis for environmental lead, especially in household dust, using thin-film principles

Abstract

Environmental lead in a variety of matrices can be determined by wavelength-dispersive X-ray fluorescence (XRF) spectrometry using thin-film principles. Transfer tape or double-coated adhesive tape is attached to a disc that fits the spectrometer's sample changer and a powdered sample is applied to the tape. Except for direct interferences, matrix effects are absent and the graph of net counts per second per unit mass against concentration is linear and passes through the origin. Using a single reference standard, lead concentration is calculated using the equation [Pb]_x=(C_xm_s/C_sm_x)[Pb_s], where [Pb] is lead concentration, C is net count rate, m is mass and subscripts x and s designate unknown and standard, respectively. A test of the method using Canadian CCRMP reference materials FeR-1 and SY-2, American USGS standard GXR-2 and French ANRT standard VS-N, which cover the range from 85 to 5200 µg g^–1 Pb, shows that lead can be determined by this method with an analytical error of 10% relative. Details of the procedure are given and the device for mounting and attaching the adhesive tape and for mounting the sample is shown. A practical application of the method to the determination of lead in household dust at the 540 µg g^–1 level with 5% precision for samples weighing about 10 mg is described and it is shown that the method compares favourably with flame atomic absorption spectrometry for 0.5 g samples.