Quantitative Analysis of Trace Elements in Microplastics Using Transportable XRF Spectrometer

ABSTRACT In this study, we investigated accurate quantitative analysis of trace elements (Cr, Fe Co, Cu, Zn, Br, and Pb) in microplastics using a transportable x‐ray fluorescence (XRF) spectrometer. The correction of XRF intensity of analyte elements was performed by the proposed correction equations and using the prepared polyester calibration standards for the correction of the sample thickness and sample size. The proposed correction method was effective for microplastic samples, but the analytical errors were larger for microplastic samples of 2 mm in diameter. The effect of the matrix effects due to sample composition was investigated by analyzing polyethylene certified reference material (CRM). The quantitative values of analytes were in general agreement with the certified values of the CRMs. The proposed method was actually applied to 94 microplastic samples collected at Japanese beach sands, and quantitative values for the analyte elements were obtained from 49 microplastic samples. Analytical results for Cr, Pb, and Br, which are designated as hazardous substances by the RoHS Directive, were obtained from 20 samples for Cr, 9 samples for Pb, and 2 samples for Br, respectively. The respective correlations between the concentrations of the analyte elements suggest that the origin of Cr and Pb in the microplastic samples is inorganic pigments (PbCr 2 O 7 : chrome yellow, or (Zn,Fe)(Fe,Cr) 2 O 4 ): brown 33) or anticorrosive paints (ZnCrO 4 ).