Preliminary studies for the standardization of a pXRF analyzer via ICP-OES for the accurate quantification of Pb in new paint†

Determining lead (Pb) concentrations in new paints using spectroscopic methods such as Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) requires technical expertise, consumables, equipment for method preparation, and instrumentation that can be cost prohibitive and difficult to maintain in low and middle-income countries (LMICs). Although portable X-ray Fluorescence (pXRF) analyzers are less expensive and simple to operate, their inaccuracy has limited their use to screening for the analysis of Pb in new, dried paint. To determine the limits of pXRF analyzers, new paint samples were purchased, dried, homogenized, and analyzed via pXRF and ICP-OES. Pb concentrations determined via pXRF were ∼27% lower than those determined by ICP-OES. Interestingly, the concentrations determined by both methods exhibited a strong linear correlation. The resulting equations were used to calibrate an individual pXRF analyzer, improving the accuracy of the pXRF result to within ±4.4% of verified concentrations of two certified reference materials. Additionally, eleven new paint samples from Benin and Türkiye were analyzed via pXRF, and their calculated concentrations were similar within ±10% of concentrations as verified by ICP-OES. This method requires no acid digestion or dilutions and provides an alternative method for the determination of Pb in new paint in LMICs.