UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, D.C. 20460
VSBy
ENVIRONMENTAL TECHNOLOGY
VERIFICATION PROGRAM
ENVIRONMENTAL TECHNOLOGY VERIFICATION PROGRAM
VERIFICATION STATEMENT
TECHNOLOGY TYPE: FIELD PORTABLE X-RAY FLUORESCENCE ANALYZER
APPLICATION: MEASUREMENT OF METALS IN SOIL
TECHNOLOGY NAME: SEFA-P ANALYZER
COMPANY:
ADDRESS:
PHONE:
HNU SYSTEMS, INC.
160 CHARLEMONT ST.
NEWTON HIGHLANDS, MA 02161-9987
(617) 964-6690
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' The U.S. Environmental Protection Agency (EPA) has created a program to facilitate the deployment of innovative
technologies through performance verification and information dissemination. The goal of the Environmental
Technology Verification (ETV) Program is to further environmental protection by substantially accelerating the
acceptance and use of improved and more cost-effective technologies. The ETV Program is intended to assist and
inform those involved in the design, distribution, permitting, and purchase of environmental technologies. This
document summarizes the results of a demonstration of the HNU SEFA-P Analyzer.
PROGRAM OPERATION
The EPA, in partnership with recognized testing organizations, objectively and systematically evaluates the
performance of innovative technologies. Together, with the full participation of the technology developer, they
develop plans, conduct tests, collect and analyze data, and report findings. The evaluations are conducted according
to a rigorous demonstration plan and established protocols for quality assurance. The EPA's National Exposure
Research Laboratory, which conducts demonstrations of field characterization and monitoring technologies,
selected PRC Environmental Management, Inc., as the testing organization for the performance verification of field
portable X-ray fluorescence (FPXRF) analyzers.
DEMONSTRATION DESCRIPTION
In April 1995, the performance of seven FPXRF analyzers was determined under field conditions. Each analyzer
was independently evaluated by comparing field analysis results to those obtained using approved reference
methods. Standard reference materials (SRM) and performance evaluation (PE) samples also were used to
independently assess the accuracy and comparability of each instrument.
The demonstration was designed to detect and measure a series of inorganic analytes in soil. The primary target
analytes were arsenic, barium, chromium, copper, lead, and zinc; nickel, iron, cadmium, and antimony were
secondary analytes. The demonstration sites were located in Iowa (the RV Hopkins site) and Washington (the
ASARCO site). These sites were chosen because they exhibit a wide range of concentrations for most of the target
metals and are located in different climatological regions of the United States; combined, they exhibit three distinct
soil types: sand, clay, and loam. The conditions at these sites are representative of those environments under which
the technology would be expected to operate. Details of the demonstration, including a data summary and
EPA-VS-SCM-05
The accompanying notice is an integral part of this verification statement
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discussion of results, may be found in the report entitled "Environmental Technology Verification Report, Field
Portable X-ray Fluorescence Analyzer, HNU Systems SEFA-P," The EPA document number for this report is
EPA/6GG/R-97/144,
The EPA Method 6200 was tested and validated using the data derived from this demonstration. This method may
be used to support the general application of FPXRF for environmental analysis.
TECHNOLOGY DESCRIPTION
This analyzer operates on the principle of energy dispersive X-ray fluorescence spectroscopy where the
characteristic energy components of the excited X-ray spectrum are analyzed directly by an energy proportional
response in an X-ray detector. Energy dispersion affords a highly efficient, full-spectrum measurement which
enables the use of low intensity excitation sources (such as radioisotopes) and compact battery-powered, field-
portable electronics. The FPXRF instruments are designed to provide rapid analysis of metals in soil. This
information allows investigation and remediation decisions to be made on-site and reduces the number of samples
that need to be submitted for laboratory analysis. In the operation of these instruments, the user must be aware that
FPXRF analyzers do not respond well to chromium and that detection limits may be 5 to 10 times greater than
conventional* laboratory methods. As with all field collection programs, a portion of the samples should be sent
to a laboratory for confirmatory analyses.
The SEFA-P Analyzer can use up to three radioactive sources with a lithium-drifted silicon detector to analyze a
large number of metals in a variety of matrices. The SEFA-P is a transportable(weighs about 50 pounds) analyzer
that operates in the intrusive mode (it only measures samples in cups). The SEFA-P Analyzer was able to measure
all 10 target analytes for this demonstration. Most of the sample analysis data were collected after the actual
demonstration. TheSEFA-P Analyzer supplied by the developer experienced a malfunction when the source holder
locked into place, not allowing sample exposure and analysis. This incident occurred at the start of the
demonstration at the ASARCO site, HNU was unable to supply a replacement unit in time to continue the
demonstration; an EPA-owned SEFA-P Analyzer was subsequently used to analyze a subset of 100 demonstration
samples. The samples chosen represented all three soil types, a wide range of concentrations fromeach of the sites,
and included all of the PE and SRM samples from the demonstration. The SEFA-P Analyzer with three sources
cost $49,000 at the time of the demonstration.
VERIFICATION OF PERFORMANCE
The performance characteristics of the SEFA-P Analyzer include the following:
• Detection limits: Precision-based detection limits were determined by collecting 10 replicate measurements
on site-specific soil samples with metals concentrations 2 to 5 times the expected MDLs. The results were 120
milligrams per kilogram (mg/kg) for antimony and lead, 225 mg/kg for copper, and 360 mg/kg for arsenic. No
values were reported for cadmium, chromium, or nickel due to an insufficient number of samples in the target
concentration range. Values for iron, zinc, and barium were 900,990, and 1150 mg/kg, respectively.
• Throughput: Average throughput was found to be 7 to 8 analyses per hour using a live count time of 240
seconds. This rate only represents the analysis time since different personnel were used to prepare the samples.
• Drift: A quantitative assessment of driftwas performed using a calibration check standard which was analyzed
at the beginning and end of each day. The drift RSD values for the mean recovery of the target analytes ranged
from 0 to 35 percent,
• Completeness: The SEFA-P Analyzer produced results for 100 of the 100 samples for a completeness of 100
percent, However, prior to the mechanical failure in the field, the SEFA-P Analyzer was to have analyzed 630
samples,
• Blank results: None of the target analytes were reported above the precision-based method detection limits
in the lithium carbonate blanks.
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• Precision: The goal of the demonstration was to achieve relative standard deviations (RSD) less than 20
percent at analyte concentrations 5 to 10 times the method detection limits. The RSD values for antimony,
barium, copper, and lead were less than 8 percent. The number of samples limited a complete assessment of
this parameter; no values were reported for arsenic, cadmium, chromium, iron, nickel, or zinc.
• Accuracy: Accuracy was assessed using site-specific soil PE samples and soil SRMs. The SEFA-P Analyzer
reported 7 of 33 or 21.2 percent of all analytes in the site-specific soil PE samples and 3 of 18 or 16.7 percent
of the soil SRMs within the quantitative acceptance range of 80 - 120 percent.
• Comparability: This demonstration showed that the SEFA-P Analyzer produced data that exhibited a Iog10-
Iog10 linear correlation to the reference data. The coefficient of determination (r2) measured using a Compton
calibration represents the degree of correlation- between the reference and field data. For this demonstration,
the coefficient of determination was 0.89 for antimony, 0.95 for arsenic, 0.73 for barium, 0.64 for cadmium,
0.35 for chromium, 0.92 for copper, 0.76 for iron, 0.97 for lead, and 0.89 for zinc. No value was reported for
nickel due to limited sample data.
• Data quality levels: Using the demonstration derived precision RSD results and the coefficient of determination
as the primary qualifiers, using data generated from the Compton ratio calibrations, the SEFA-P Analyzer
produced definitive level data for copper, antimony, and lead; data of quantitative screening level were produced
for barium. Without adequate precision or comparability data, levels for the other six analytes could not be
assigned.
The results of the demonstration show that the HNU SEFA-P portable X-ray fluorescence analyzer can provide
useful, cost-effective data for environmental problem-solving and decision-making. Undoubtedly, it will be
employed in a variety of applications, ranging from serving as a complement to data generated in a fixed analytical
laboratory to generating data that will stand alone in the decision-making process. As with any technology
selection, the user must determine what is appropriate for the application and the project data quality objectives.
Gary J. Foley, Ph.D.
Director •
National Exposure Research Laboratory
Office of Research and Development
NOTICE: EPA verifications are based on an evaluation of technology performance under specific, predetermined criteria and the
appropriate quality assurance procedures. EPA makes no expressed or implied warranties as to the performance of the technology
and does not certify that a technology will always, under circumstances other than those tested, operate at the levels verified. The
end user is solely responsible for complying with any and all applicable Federal, State, and Local requirements..
EPA-VS-SCM-05
The accompanying notice is an integral part of this verification statement
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March 1998
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