Application of X-ray Absorption Fine Structure (XAFS) Spectroscopy to Speciation of Lead (Pb) Contaminants in Plastics

摘要

A study using X-ray absorption fine structure (XAFS) spectroscopy in conjunction with chemical analyses was undertaken to determine the form of lead (Pb) compound(s) used as additives in plastic bags. Comparison of Pb L-III-edge X-ray absorption near-edge structure (XANES) in samples with those of the standards, and XANES simulation studies revealed that spectra of samples were almost identical to that of PbCrO4, and ca. 80% of Pb was present in the form of PbCrO4. These findings were supported by the facts that Cr-XANES spectra of samples resembled that of PbCrO4, and Cr/Pb molar ratios in samples calculated from simulation of XANES agreed reasonably well with those of the chemical data. Results of k(3)-weighted extended X-ray absorption fine structure (EXAFS) spectra of three of the samples showed that they resembled that of the PbCrO4.