| X-ray fluorescence (XRF) spectrometry is a well-established analytical technique for determining the elemental content of many different materials. XRF has long been used for public health applications, particularly for identifying lead-based paint hazards. The primary advantage of XRF over other atomic spectrometric techniques is that it is nondestructive. In addition, little sample preparation is required, so results are obtained rapidly and at low cost. The principal aim of this study was to characterize the utility and reliability of current XRF instrumentation for use in the environmental health sciences. Interest in the use of XRF for detecting lead in children's toys rapidly increased in 2007 due to the large numbers of contaminated products imported into the United States from China. However, little is known about the accuracy and limitations of new XRF instrumentation designed for specific applications in environmental health, so this study is intended to elucidate these aspects.;A key goal of this study was to investigate several prototype XRF instruments manufactured by X-Ray Optical Systems (XOS, East Greenbush, NY) with NIH funding and designed to solve some very specific problems. These included three novel instruments based on monochromatic XRF (M-XRF) that were designed for determination of (a) lead in toys (HD-Prime), (b) trace elements in body fluids (Body Fluids Analyzer), and (c) trace elements in environmental samples (Personal Environmental Analyzer). For each of these applications, the reliability of the XRF instrumentation was assessed using a variety of certified reference materials (CRM) and numerous 'real world' samples. The XRF results were compared to certified values or to reference values determined by conventional "gold standard" analytical techniques. In addition to assessing the M-XRF instrumentation from XOS, a commercially available handheld XRF analyzer (Niton XL3t) was evaluated and compared.;The XOS HD-Prime instrument was capable of detecting Pb in paint coatings with reasonable reliability for identifying hazardous levels in children's products, and bias was generally <20%. By contrast the Body Fluids Analyzer was not suitable for detecting toxic metals in blood or urine at low levels that are consistent with the needs of biomonitoring studies. However, the performance of the prototype was sufficient for detecting and quantitating essential trace elements such as Cu, Zn and to a lesser extent, Se. The performance of the Personal Environmental Analyzer was somewhat variable when detecting elevated levels of trace elements. Quantitation based on the use of fundamental parameters software proved elusive for some elements (e.g., As, Al), and reasonable for other elements depending on the sample matrix. In general, the M-XRF technology was more sensitive than the handheld instrumentation, while the latter was more versatile. Overall, this study demonstrated that modern XRF instrumentation is a useful tool for the public health laboratory, particularly for rapid screening purposes. |
