Superfund Innovative Technology Evaluation (SITE)
Note: EPA no longer updates this information, but it may be useful as a reference or resource.
|ETV Field Portable X-ray Fluorescence Analyzer Metorex X-MET 920-MP
In April 1995, the U.S. Environmental Protection Agency (EPA) conducted a demonstration of field portable X-ray fluorescence (FPXRF) analyzers. The primary objectives of this demonstration were (1) to determine how well FPXRF analyzers perform in comparison to standard reference methods, (2) to identify the effects of sample matrix variations on the performance of FPXRF, (3) to determine the logistical and economic resources needed to operate these analyzers, and (4) to test and validate an SW-846 draft method for FPXRF analysis. The demonstration design was subjected to extensive review and comment by the EPA's National Exposure Research Laboratory, EPA Regional and Headquarters Superfund technical staff, the EPA's Office of Solid Waste-Methods Section, and the technology developers.
Two sites were used for this demonstration: the RV Hopkins site and the ASARCO Tacoma Smelter site (ASARCO). RV Hopkins is an active steel drum recycling facility and a former battery recycling operation. It is located in Davenport, Iowa. The ASARCO site is a former copper and lead smelter and is located in Tacoma, Washington. The test samples analyzed during this demonstration were evenly distributed between three distinct soil textures: sand, loam, and clay. The reference methods used to evaluate the comparability of data were EPA SW-846 Methods 3050A and 6010A, "Acid Digestion of Sediments, Sludges, and Soils" and "Inductively Coupled Plasma-Atomic Emission Spectroscopy," respectively.
The FPXRF analyzers tested in this demonstration were designed to provide rapid, real-time analysis of metals concentrations in soil samples. This information will allow investigation and remediation decisions to be made on-site more efficiently and can reduce the number of samples that need to be submitted for confirmatory analysis. Of the seven commercially available analyzers tested, one is manufactured by Niton Corporation (the XL Spectrum Analyzer); two are manufactured by TN Spectrace (the TN 9000 and TN Pb Analyzer); two are manufactured by Metorex Inc. (the X-MET 920-P Analyzer and the X-MET 920- MP Analyzer); one is manufactured by HNU Systems, Inc. (the SEFA-P Analyzer); and one is manufactured by Scitec Corporation (the MAP Spectrum Analyzer). The X-MET 940, a prototype FPXRF analyzer developed by Metorex, was given special consideration and replaced the X-MET 920-P for a portion of the demonstration. This environmental technology verification report (ETVR) presents information relative to the Metorex X-MET 920-MP. Separate ETVRs have been published for the other analyzers demonstrated.
Approximately three days of operational downtime was experienced by the analyzer due to computer software and hardware problems. Most of these problems were due to operator error or inexperience. None of the downtime or data loss was associated with mechanical or electronic malfunctions of the analyzer. Quantitative data was provided by the analyzer on a real-time basis. The X-MET 920-MP Analyzer reported arsenic, chromium, copper, lead, zinc, nickel, and barium. This analyzer used count times ranging from 30 live-seconds for in situ-unprepared samples at the ASARCO site to 180 live-seconds for intrusive-prepared samples at the RV Hopkins site. These count times resulted in a sample throughput averaging between 8 and 14 samples per hour. The X-MET 920-MP Analyzer provided definitive data(equivalent to reference data) for arsenic and lead; and qualitative screening level data (identifies the presence or absence of a contaminant) for copper, barium, and zinc. Insufficient precision data precluded an assignment of data quality levels for nickel or chromium.
This study showed that the analyzer produced data that exhibited a log10 -log10 linear correlation to the reference data. The analyzer generally exhibited a precision similar to the reference methods. The analyzer exhibited precision of less than 10 percent relative standard deviation at 5 to 10 times the method detection limit (MDL) for all of the reported analytes except chromium and nickel. The precision evaluation was confounded by changing count times. The precision study indicated that count times probably had no effect on the precision for all target analytes except copper and lead. For copper and lead, the increasing count times caused a 2- to a 10-fold increase in precision. The analyzer's quantitative results were based on an empirical calibration using site-specific calibration samples.
This demonstration found that the X-MET 920-MP Analyzer was generally simple to operate in the field; however, its physical configuration made it more practical for use as a benchtop unit. The auxiliary computer and cumbersome power requirements of commercial laptop computers limited its utility as an in situ instrument. The operator required no specialized experience or training for normal operation of the analyzer. However, ownership and operation of this analyzer may require specific licensing by a state nuclear regulatory agency. There are specific radiation safety training requirements and costs associated with this type of license.
The Metorex X-MET 920-MP Analyzer can provide rapid, real-time analysis of the metals content of soil samples at hazardous waste sites. The analyzer can quickly identify contaminated areas from noncontaminated areas allowing investigation and remediation decisions to be made more efficiently on-site and reduce the number of samples that need to be submitted for confirmatory analysis.