PXRF has been successfully used to identify products that contain ppm levels of essential and toxic elements in a variety of products including foods, housewares, cosmetics, dietary supplements, drugs, and devices. PXRF has been generally used as a qualitative tool by investigators for sample selection. However, on-board pXRF algorithms aren't specifically designed for FDA regulated products. User confirmation of results usually requires examination of the spectrum. Because pXRF detection limits are variable and range from 1-100 mg/kg for many elements of interest, pXRF is not adequate for identifying some elements at levels that could pose chronic health hazards; e.g. lead (Pb) in most foods. FDA is often interested in concentrations less than 1 mg/kg.  PXRF has greater value for products typically consumed in small amounts, because target elements must be high to be of regulatory significance.  XRF in general has been used for a number of quantitative applications by FDA. XRF can guide method selection, sample preparation, and dilution requirements for some samples. Samples with high analyte concentration can pose contamination hazards for FDA facilities. Other potentially useful pXRF applications include in-facility evaluation of ingredient content of intentional additives and contaminants, and evaluations focused on lot-to-lot product uniformity. PXRF also has a potentially important role in events involving acutely toxic levels of elements. Regardless of pXRF's inability to detect all toxic elements at levels that pose excessive chronic exposures, it is a valuable tool in the field and in the lab. Intelligence, product origin, and past product history are the only factors FDA has to select samples containing low, but potentially important levels of toxic elements in regulated products. Presently, pXRF is the only portable device that allows investigators to screen products for elements of interest.

Application of portable, energy dispersive X-ray fluorescence (pXRF) analyzers to FDA regulated products

248th National Meeting (2014)

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