When performing X-ray absorption near edge structure (XANES) spectroscopy, some target elements, such as lead, tend to result in a broad featureless spectrum when using a conventional detector. Improving the energy resolution of the detector may lead to increased ability and confidence in determining the speciation of lead in environmental samples. Using a bent Laue analyser with a Pilatus area detector we were able to achieve an energy resolution on the order of less than 1 ev as opposed to over 120 ev offered by the state of the art silicon drift detectors. Using the bent Laue analyser resolved shoulders into distinct peaks and brings out features which are not apparent in the conventional XANES spectra. While the increased resolution is visually pleasing, the question remains as to whether or not the increased resolution brings any more accuracy or precision to the analysis of XANES data.<br/><br/>In this series of experiments, multiple lead mineral standards and lab prepared samples of lead adsorbed onto specific minerals were collected using both the high energy resolution fluorescence detector (HERFD) technique and a conventional quick scan method with a Lytle detector. Samples were then created using known amounts of the adsorbed lead and mineral standards to test the accuracy and precision of the HERFD and Conventional XANES analyses.<br/><br/>Despite the widespread use of XANES for lead speciation in environmental samples, there are very few studies that quantitatively investigate the performance of the technique. The conventional XANES collected in fluorescence mode using a Lytle detector also gave good results confirming that the use of XANES to determine the speciation of lead in environmental samples is a valid, useful technique. The HERFD analysis are very promising, though still somewhat preliminary. The major hurdle to overcome is the small X-ray spot size which requires a level of homogeneity that is not always possible with environmental samples. More testing will be conducted to improve the method and verify the results.

Application of high energy resolution X-ray fluorescence spectroscopy on environmental samples

254th National Meeting (2017)

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