THE ENVIRONMENTAL TECHNOLOGY VERIFICATION
PROGRAM
SERA
U.S. Environmental Protection Agency
Bairene
Ttiii Business ti/Innovation
ETV Joint Verification Statement
TECHNOLOGY TYPE: MULTI-PARAMETER WATER QUALITY PROBE
APPLICATION:
MEASURING WATER QUALITY
TECHNOLOGY NAME: RCM Mk II with Optode 3830
COMPANY: AANDERAA Instruments, Inc.
ADDRESS:
WEB SITE:
E-MAIL:
Nesttunbrekken 97
5221 Nesttun, Norway
http://www.aanderaa.com
info@aanderaa.no
PHONE: +47 55 109900
FAX: +47 55 109910
The U.S. Environmental Protection Agency (EPA) supports 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 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. Information and ETV
documents are available at www.epa.gov/etv.
ETV works in partnership with recognized standards and testing organizations, with stakeholder groups
(consisting of buyers, vendor organizations, and permitters), and with 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 pre-
paring 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 seven technology areas under ETV, is operated by
Battelle in cooperation with EPA's National Exposure Research Laboratory. The AMS Center has recently
evaluated the performance of multi-parameter water quality probes. This verification statement provides a
summary of the test results for the AANDERAA Instruments, Inc. RCM Mk II with Optode 3830.
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VERIFICATION TEST DESCRIPTION
The Mk II with Optode 3830 was evaluated by determining calibration check accuracy and by comparing Mk II with
Optode 3830 measurements with standard reference measurements and measurements from handheld calibrated
probes. Two Mk II with Optode 3830s were deployed in saltwater, freshwater, and laboratory environments near
Charleston, South Carolina, during a 3 !/2-month verification test. The saltwater site was in a tributary of Charleston
Harbor, the freshwater site was a wetlands on the campus of the National Oceanic and Atmospheric Administration
Center for Coastal Environmental Health and Biomolecular Research (CCEHBR), and the laboratory site was the
CCEHBR mesocosm facility. Water quality parameters were measured both by the Mk II with Optode 3830s and by
reference methods consisting of collocated field-portable instrumentation and analyses of collected water samples.
During each phase, performance was assessed in terms of calibration check accuracy, relative bias, precision,
linearity, and inter-unit reproducibility. Test parameters included dissolved oxygen (DO), temperature, and turbidity.
The saltwater phase lasted for 28 days, during which time the Mk II with Optode 3830 monitored the naturally
occurring range of the target parameters, collecting data every 10 minutes, 24 hours a day. For the duration of the
test, the Mk II with Optode 3830 was deployed at depths between approximately one and 10 feet, varying according
to the tide. Samples were collected at intervals throughout the test. Freshwater testing was conducted at the wetlands
on the CCEHBR campus. Because the salinity and stratification of the wetlands increased during this portion of the
deployment, an extended freshwater period was added to the end of the mesocosm deployment to provide data from
a freshwater deployment. For the mesocosm phase, the mesocosm tanks were filled with saltwater/freshwater and
drained daily, simulating a tide. Water samples were collected during each test day throughout the normal operating
hours of the facility (nominally 6 a.m. to 6 p.m.). During this phase, the mesocosm was manipulated to introduce
variations in the measured parameters. The turbidity of the system was varied by operating a pump near the sediment
trays to suspend additional solids in the water. Variations in temperature were driven by natural forces. The table
below provides a summary of the water conditions at the test sites.
Test Site Water Conditions
Parameter
DO
Temperature
Turbidity
Saltwater
Low
3 milligrams/liter
(mg/L)
20°C
8 nephelometric
turbidity units (NTU)
Freshwater
High
6 mg/L
28°C
3 7 NTU
Low
6.8 mg/L
11°C
1.7 NTU
High
11. 2 mg/L
27°C
3. 6 NTU
Mesocosm
Low
9.3 mg/L
9°C
0.4 NTU
High
12.1 mg/L
16°C
15 NTU
During this verification test approximately 12,000 data points were collected for each of the three parameters tested,
and 127 sets of reference measurements were made.
QA oversight of verification testing was provided by Battelle and EPA. Battelle QA staff conducted a technical
systems audit, a performance evaluation audit, and a data quality audit of 10% of the test data. This verification
statement, the full report on which it is based, and the test/QA plan for this verification are all available at
www.epa.gov/etv/centers/centerl.html.
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TECHNOLOGY DESCRIPTION
The following description of the Mk II with Optode 3830 was provided by the vendor and does not represent
verified information.
The Optode 3830 uses a platinum porphyrin complex as a dynamic fluorescence quencher to monitor oxygen in
water. The porphyrin complex is embedded in a gas-permeable foil that is exposed to the surrounding water. A black
optical isolation coating protects the complex from sunlight and fluorescent particles in the water. This sensing foil
is attached to a sapphire window, providing optical access for the measuring system from inside a watertight
titanium housing. The foil is excited by modulated blue light, and the phase of a returned red light is measured. By
linearizing and temperature compensating with an incorporated temperature sensor, the absolute oxygen
concentration can be determined. The diameter of the Optode 3830 is 36 millimeters (mm) (1.42 inches). It is 86 mm
(3.39 inches) long and weighs 0.23 kilograms (8.11 ounces). Pricing information is available from the vendor. The
range, resolution, and accuracy, as indicated by the vendor, are listed below.
Vendor-Provided Range, Resolution, and Accuracy
Parameter Range Resolution Accuracy
Air saturation 0 to 120% <0.4% <5%
Oxygen concentration 0 to 500 (iMolar (uM) <1 uM <8 uM or 5%, whichever is greater
Temperature -2.7 to 36.66°C 0.1% of range ±0.05°C
Turbidity 0 to 20 NTU 0.1% of full scale 2% of full scale
VERIFICATION OF PERFORMANCE
The table below summarizes the performance of the Mk II with Optode 3830. The two Mk II with Optode 3830s
collected data without interruption at 10-minute intervals from October 1, 2003, until January 5, 2004, and 100% of
the required data was collected.
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Performance Results
Statistical Measure Parameter
Calibration check DO (%)
accuracy^'
Turbidity (%)
Average relative bias(c) DO (%)
Temperature (%)
Turbidity (%)
Average precision DO (%RSD)
Temperature
(%RSD)
Turbidity (%RSD)
Linearity
Inter-unit reproducibility DO (mg/L)
Temperature (°C)
Turbidity (NTU)
1103 1104
Saltwater Freshwater Mesocosm Saltwater Freshwater Mesocosm
98.9 98.9 99.7 97.3 95.6 83.9
30 1,500 NA® 18 800 520
-19.7 -(d) -6.79 -13.8 -(d) 6.61
-0.99 -(d) -1.76 -1.76 -(d) -1.51
54.2 -(d) -521 69.0 -(d) -452
1103 1104
1.32 0.73
2.20 2.80
26.8 24.4
Best agreement between readings and reference values was for temperature.
During the saltwater deployment, the DO measurements resulted in slopes
between 0.70 and 0.74 and regression coefficients between 0.76 and 0.79 over
a range of 3 to 6 mg/L. During the mesocosm deployment, slopes and
regression coefficients both decreased. Finally, when the Mk II was within its
range, the turbidity measurements resulted in a slope of 0.99 and a regression
coefficient of 0.93 over a range of 0.4 to 15 NTU.
Average Difference Between 1103 and 1104 Readings
Saltwater Freshwater Mesocosm
1.02 1.42 1.78
0.16 0.04 0.03
3.12 10.9 7.26
^ The closer the percentage is to 100, the better.
^ Saturated; no data reported.
^ The closer the percentage is to zero, the better.
^ Stratification; no data reported.
Original signed bv Gabor J. Kovacs 7/27/04 Original signed bv Gary J. Folev 9/13/04
Gabor J. Kovacs Date Gary J. Foley Date
Vice President Director
Energy and Environment Division 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.
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