THE ENVIRONMENTAL TECHNOLOGY VERIFICATION


PROGRAM


U.S. Environmental Protection Agency 

ETV Joint Verification Statement


TECHNOLOGY TYPE: Continuous Emission Monitor 

APPLICATION:	 MEASURING MULTIPLE METALS IN STACK GAS 

TECHNOLOGY 

NAME: XCEM Multi-Metals Continuous Emission Monitor 

COMPANY:	 Cooper Environmental Services 

ADDRESS:	 10170 S.W. Nimbus Avenue PHONE: 503-624-5730 

Suite H-5 FAX: 503-624-2120 

Portland, OR 97223 

WEB SITE: 

E-MAIL:	 JohnsenCES@aol.com 

The U.S. Environmental Protection Agency (EPA) has created the Environmental Technology Verification (ETV) 

Program to facilitate the deployment of innovative or improved environmental technologies through performance 

verification and dissemination of information. The goal of the ETV Program is to further environmental protection 

by substantially accelerating the acceptance and use of improved and cost-effective technologies. ETV seeks to 

achieve this goal by providing high-quality, peer-reviewed data on technology performance to those involved in the 

design, distribution, financing, permitting, purchase, and use of environmental technologies. 

ETV works in partnership with recognized standards and testing organizations; with stakeholder groups that consist 

of buyers, vendor organizations, and permitters; and with the full participation of individual technology developers. 

The program evaluates the performance of innovative technologies by developing test plans that are responsive to 

the needs of stakeholders, conducting field or laboratory tests (as appropriate), collecting and analyzing data, and 

preparing peer-reviewed reports. All evaluations are conducted in accordance with rigorous quality assurance (QA) 

protocols to ensure that data of known and adequate quality are generated and that the results are defensible. 

The Advanced Monitoring Systems (AMS) Center, one of six technology centers under ETV, is operated by Battelle 

in cooperation with EPA’s National Exposure Research Laboratory. The AMS Center has recently evaluated the 

performance of the Cooper Environmental Services X-ray based continuous emission monitor (XCEM). This 

verification statement provides a summary of these test results. 
VERIFICATION TEST DESCRIPTION 

The objective of the verification test was to quantitatively evaluate the performance of the XCEM under real-world 

conditions. Verification testing took place at the Tooele Army Depot (TEAD) Building 1320 deactivation 

incinerator. The XCEM was tested for its ability to measure five elements found in the feedstream—antimony (Sb), 

barium (Ba), cadmium (Cd), chromium (Cr), and lead (Pb), as well as arsenic (As), mercury (Hg), nickel (Ni), and 

zinc (Zn). Except for Pb, the stack gas levels of these target metals were prepared by spiking metal solutions into 

the stack gas at the base of the stack. Stack gas metal concentrations were simultaneously determined by the XCEM 

and by two EPA Method 29 (M29) sampling trains. The M29 trains sampled for two hours, while XCEM data, 

which are recorded every 20 minutes, were averaged over each M29 run. A total of 13 dual M29 runs were 

performed by the U.S. Army Center for Health Promotion and Preventive Medicine (CHPPM) Air Quality 

Surveillance Program. In all cases, when reference method data were being taken, the spiking of the indicated metals 

was held constant throughout the entire sampling period to allow comparisons of XCEM data to reference method 

data under constant conditions. CHPPM’s Directorate of Laboratory Services conducted laboratory analysis of the 

M29 sampling trains. The test activities provided data for verifying the relative accuracy (RA); correlation with 

reference method; precision; span, zero, and internal standard drift; bias; and response time. RA was determined by 

comparing M29 results to simultaneous XCEM results averaged over the M29 sampling periods. The RA of the 

XCEM with respect to M29 was assessed by 

S d + t n

α

−1 

d

RA = n ×100%

x

Where d refers to the difference between corresponding M29 and XCEM results, n is the number of runs, and x is 

the average M29 result. Sd denotes the sample standard deviation of the differences, while t�

n-1 is the t value for the 

100(1-α)

th percentile of the distribution with n-1 degrees of freedom. The RA was determined for an α value of 

0.025 (i.e., 97.5% confidence level, one-tailed). Correlation of XCEM and M29 results was calculated using the 

same data used to calculate RA. Precision of the XCEM was calculated in terms of the percent relative standard 

deviation (RSD) of successive XCEM readings during periods of stable metal concentrations. 

Drift was checked by automated daily XCEM span and zero QA measurements. Bias relative to M29 was identified 

using EPA Method 301 (M301) protocols. Response time was determined as the time between the start of one 

XCEM sampling period and the beginning of the next sampling period. 

Battelle and EPA provided QA oversight of verification testing. Battelle QA staff conducted a data quality audit of 

10% of the test data, and Battelle’s Quality Manager performed an internal technical systems audit of the 

verification test during testing at the TEAD incinerator. Battelle, with the assistance of CHPPM staff, performed a 

series of performance evaluation audits to check the quality of reference measurements made in the verification test. 

A technical systems audit report was submitted to EPA Quality Management staff. 

TECHNOLOGY DESCRIPTION 

The XCEM extracts a sample of stack gas and concentrates the metals of interest on a chemically treated filter tape. 

Following collection, the filter tape advances, moving the sample spot to an analysis area where a laboratory-grade 

X-ray fluorescence (XRF) instrument is used to determine metal mass. The system is automated and can produce 

concentration data every 10 to 20 minutes for 19 elements of interest. The XCEM components include the 

extraction system, the sampling and analysis system, and the control system. The XCEM extraction system collects 

a representative stack gas sample from the stack and transports the sample to the filter tape. Upon entrance into the 

XCEM housing, the stack gas passes through a heat-traced stilling chamber that expands the tubing diameter and 

slows the gas velocity. An eductor, located downstream of the stilling chamber, is used to pull the stack gas through 

the extraction system. Of the two to three standard cubic feet per minute that pass through the stilling chamber, a 

sub-sample of approximately 0.8 liter per minute is extracted and directed through a filter tape, concentrating the 

metals sample for analysis. Following filtration, the stack gas is subsequently transported to the XCEM chassis 
where drying and volume determination take place. The excess (i.e., unfiltered) stack gas is transported out of the 

stilling chamber through a flowmeter and is vented or returned to the stack. The sampling cassette holds a fourweek supply of filter tape on a reel-to-reel system that is automated to accurately move the tape from the sampling 

to the analysis position. Sampling and analysis occur simultaneously, resulting in a continuous monitoring system 

that produces metal concentration values every 10 to 20 minutes. Metal mass on the filter is determined using a 

modified ThermoNoran QuanX energy dispersive XRF analyzer. The XCEM has an automated check for internal 

standard drift that measures a palladium (Pd) standard with each XCEM analysis. 

The XCEM is controlled by a personal computer using a custom WonderWare software interface. All day-to-day 

functions of the XCEM are automated, including flow and temperature control, concentration determination, and 

QA routines. Flow, temperature, concentration, pressure, and error messages are automatically recorded in a secure 

database. The data can be imported into Excel or an equivalent program for subsequent analysis. Flows, 

temperatures, concentrations, and pressure are logged in real time on the screen computer monitor. 

VERIFICATION OF PERFORMANCE 

Relative Accuracy: The XCEM relative accuracy for Cd, Cr, and Ni was less than 26% (less than 20% calculated 

for nine runs). The remaining metals (As, Ba, Hg, Pb, Sb, and Zn) had RA values between 37 and 67%. The RA 

for Pb was 36.7% calculated for nine runs. The reported XCEM concentrations were uniformly high for As. The 

XCEM was consistently low for Zn, Ba, and Sb. XCEM Hg readings were very low at the start of each test day, 

rising gradually until they stabilized. The best agreement of XCEM and M29 Hg results (within about 20%) was 

found with M29 runs conducted late in the test day, when XCEM readings had stabilized. 

Correlation with Reference Method: Correlation of XCEM and M29 results was calculated for five elements that 

varied enough during the test to justify this comparison. For Ni, Pb, Sb, and Zn, r2

 values exceeding 0.95 were 

found, although the r2

 value for Pb decreased to 0.75 when the high Pb levels in Runs 1 and 2 were excluded. For 

Hg, an r2

 value of 0.39 was found. 

Precision: The XCEM’s precision ranged from 6 to 21% over the nine target metals. This precision includes 

variability in the metals injection and the test facility, as well as in the XCEM itself. 

Span, Zero, and Internal Standard Drift: XCEM span and zero drift were assessed over the four test days. Daily 

span readings of Cd, Cr, Hg, and Pb exhibited RSD values of 0.47 to 2.33% and no significant trends over time. 

Zero readings for all four elements were near or below the respective detection limits on all test days. The RSD of 

the XCEM’s Pd internal standard was approximately 2.5%. 

Bias: The XCEM results showed statistically significant positive or negative bias relative to M29 results for all the 

target metals, based on M301 procedures. 

Response Time and Other Parameters: The XCEM functioned in an automated manner and automatically 

recorded concentrations, temperatures, flow rates, and QA data. It exhibited no mechanical problems, had an 

effective up time of 100%, and a response time of 20 minutes. 

original signed by Gabor J.Kovacs 5/4/02 original signed by Gary J. Foley 8/15/02 

Gabor J. Kovacs Date Gary J. Foley Date 

Vice President Director 

Environmental Sector National Exposure Research Laboratory 

Battelle Office of Research and Development 

U.S. Environmental Protection Agency 
NOTICE: ETV verifications are based on an evaluation of technology performance under specific, 

predetermined criteria and the appropriate quality assurance procedures. EPA and Battelle make no expressed 

or implied warranties as to the performance of the technology and do not certify that a technology will always 

operate as verified. The end user is solely responsible for complying with any and all applicable federal, state, 

and local requirements. Mention of commercial product names does not imply endorsement.