Superfund Innovative Technology Evaluation (SITE)
Note: EPA no longer updates this information, but it may be useful as a reference or resource.
XRF Technologies for Measuring Soil
The Niton XLt 700 Series (XLt) XRF Services x-ray fluorescence (XRF) analyzer was demonstrated under the U.S. Environmental Protection Agency (EPA) Superfund Innovative Technology Evaluation (SITE) Program. The field portion of the demonstration was conducted in January 2005 at the Kennedy Athletic, Recreational and Social Park (KARS) at Kennedy Space Center on Merritt Island, Florida. The demonstration was designed to collect reliable performance and cost data for the XLt analyzer and seven other commercially available XRF instruments for measuring trace elements in soil and sediment. The performance and cost data were evaluated to document the relative performance of each XRF instrument.
This innovative technology verification report describes the objectives and the results of that evaluation and serves to verify the performance and cost of the XLt analyzer. Separate reports have been prepared for the other XRF instruments that were evaluated as part of the demonstration. The objectives of the evaluation included determining each XRF instrument’s accuracy, precision, sample throughput, and tendency for matrix effects. To fulfill these objectives, the field demonstration incorporated the analysis of 326 prepared samples of soil and sediment that contained 13 target elements.
The prepared samples included blends of environmental samples from nine different sample collection sites as well as spiked samples with certified element concentrations. Accuracy was assessed by comparing the XRF instrument’s results with data generated by a fixed laboratory (the reference laboratory). The reference laboratory performed element analysis using acid digestion and inductively coupled plasma – atomic emission spectrometry (ICP-AES), in accordance with EPA Method 3050B/6010B, and using cold vapor atomic absorption (CVAA) spectroscopy for mercury only, in accordance with EPA Method 7471A.
The Niton XLt is a small, field-portable instrument designed for chemical characterization of soils, sediment, and other thick homogeneous samples (plastics and metals). The analyzer features a miniaturized x-ray tube for the excitation source and a Peltier-cooled Si-PiN x-ray detector. The analyzer’s standard software is programmed to analyze and automatically report 25 elements. The Niton XLt analyzer is designed to be used as either a hand-held instrument for in situ analysis or as a bench-top instrument, in a test stand with a sample drawer below the instrument, for ex situ analysis. The Niton XLt analyzer can be used to analyze elements under three primary scenarios: (1) bulk sample mode (includes soils, sediments, and metal alloys); (2) thin film mode (includes dust wipes and filters); and (3) plastics mode. XRF analyses using the Niton XLt analyzer comply with EPA Method 6200, “Field Portable XRF Spectrometry for the Determination of Elemental Concentrations in Soil and Sediment.”
This report describes the results of the evaluation of the XLt analyzer based on the data obtained during the demonstration. The method detection limits, accuracy, and precision of the instrument for each of the 13 target analytes are presented and discussed. The cost of element analysis using the XLt analyzer is compiled and compared to both fixed laboratory costs and average XRF instrument costs.