Performance Evaluation of Currently Used Portable X ray Fluorescence Instruments for Measuring the Lead Content of Paint in Field Samples

Abstract

Field-portable X-ray fluorescence (FP-XRF) instruments are important for non-destructive, rapid and convenient measurements of lead in paint, in view of potential remediation. Using real-life paint samples, we compared measurements from three FP-XRF instruments currently used in Switzerland with laboratory measurements using inductively coupled plasma mass spectrometry after complete sample dissolution. Two FP-XRF devices that functioned by lead L shell excitation frequently underestimated the lead concentration of samples. Lack of accuracy correlated with lead depth and/or the presence of additional metal elements (Zn, Ba or Ti). A radioactive source emitter XRF that enabled the additional K shell excitation showed higher accuracy and precision, regardless of the depth of the lead layer in the sample or the presence of other elements. Inspection of samples by light and electron microscopy revealed the diversity of real-life samples, with multi-layered paints showing various depths of lead and other metals. We conclude that the most accurate measurements of lead in paint are currently obtained with instruments that provide at least sufficient energy for lead K shell excitation.

KEYWORDS:

• field samples
• hand-held X-ray fluorescence
• inductively coupled plasma mass spectrometry
• lead
• lead-based paint XRF
• lead diagnostic
• scanning electron microscopy

ACKNOWLEDGMENTS

We would like to especially thank Jean-Luc Bailly, Marie-José Clerc, Nicole Perruchoud, Wanda Stryjenska, and Gilbert Pfister for their help in performing experimental work. We also wish to acknowledge Jasmin Meltretter for useful comments on the project and Agathe Martignier for electron microscopy data as well as Ron Hogg for careful and critical reading of the manuscript.