Rapid screening of bioaccessible Pb in URBAN soils using pXRF

U.S. EPA method 1340 (Bioaccessibility assay of lead in soils) requires well-equipped laboratories that are capable of measuring Pb in extract solutions using advanced instrumentation such as ICP-MS with high precision. In this study, we propose a new approach for low cost and rapid assessment of soil Pb bioaccessibility that can be conducted in the field using a portable X-Ray Fluorescence (pXRF) analyzer. Air dried soil samples were extracted with a soil:extract ratio of 1:10 for one hour at room temperature, and the filtered extractant was directly measured in cups by pXRF. Results showed that pXRF can measure Pb directly in liquid samples. The pXRF readings were consistently ~15% higher than expected. There was no significant matrix effect. The results of bioaccessibility of Pb determined by the simplified acid leaching methods with glycine solution at pH 1.5, 1 N HNO3 and 1 N HCl were deviated from those determined with the standard EPA method 1340. More research is needed to find the best protocol that can utilize the pXRF and yield similar results to the EPA method 1340. © Springer International Publishing AG, part of Springer Nature 2019.