In situ elemental characterisation of marine microplastics by portable XRF

The performance of a portable x-ray fluorescence spectrometer configured in a test stand and coupled to a laptop has been evaluated for the determination of various elements (including Br, Cd, Cl, Cr, Cu, Fe, Pb and Zn) in beached microplastics. Under laboratory conditions, analysis of samples that covered the 3-mm x-ray beam returned concentrations that, on average, were within 20% of concentrations determined by ICP following acid digestion. Analysis of progressively smaller offcuts (to <1mm) resulted in corresponding concentrations that were comparable to those determined in original samples but errors and detection limits that progressively increased. When the configuration was deployed in situ with two operators, up to 35 microplastics counted for 60s each could be processed per hour. Advantages of immediate measurements include the development of an iterative study strategy, rapid compliance-evaluation, and identification of specific materials for further characterisation or study in the laboratory.