Performance Verification Statement for the Real Tech Real Nitrate Analyzer GL Series

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Ref. No. [UMCES] CBL 2017-050
ACT VS17-05
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– Salinity levels were developed using Instant Ocean additions to the RO water matrix, which
could have contributed trace amounts of nutrients, but would have measured in the final
reference samples.
– Instruments were exposed for three hours at each of the 3 concentrations with reference
samples collected every 30 minutes following an initial 30 minute equilibration period to
each condition.
Test 4: Turbidity Response
– Accuracy and precision were tested over two elevated turbidity levels (approximately 10
and 100 NTU) at the C3 concentration level of the range test at 20 oC.
– Test tanks were continuously mixed with submersed pumps but there was some settling of
the material as noted by continuous monitoring with the EXO2 sonde and analysis of
discrete turbidity samples on the Hach 2100.
– Turbidity concentrations were established using Elliot Silt Loam reference material (cat #
1B102M) available from the International Humic Substances Society -
) added into RO water matrix.
– Instruments were exposed for three hours at each of the 3 concentrations with reference
samples collected every 30 minutes following an initial 30 minute equilibration period to
each condition.
Test 5: DOC Response
– Accuracy and precision were tested against two DOC levels (1 and 10 mg/L) at the C3
concentration level of the range test at 20 oC.
– DOC concentrations were established using the Upper Mississippi River Natural Organic
Matter standard (cat# 1R110N) available from the International Humic Substances Society
added to RO water matrix.
– Instruments were exposed for three hours at each of the 3 concentrations with reference
samples collected every 30 minutes following an initial 30 minute equilibration period to
each condition.
Field Tests
In situ field performance evaluations of the test instruments were conducted under extended
mooring deployments at three ACT Partner Institution sites covering freshwater, estuarine, and
marine conditions. Site specific details for each test site were as follows:
Freshwater Deployment : The freshwater deployment occurred on the Maumee River in
Waterville, OH for one month duration and provided a high nutrient, high turbidity test
environment. The ACT Partner at the University of Michigan established a flow-through system on
the Maumee River near Waterville Ohio (83.74 oN; 41.48 oW), located within the pump house of
the City of Bowling Green Municipal Water Treatment Plant. Instruments were deployed in a 180
gallon flow-through tank with a water depth of approximately 0.8m and exchange time of
approximately 10 minutes. The Maumee River main stem flows 137 km before flowing into the
Maumee Bay of Lake Erie at the city of Toledo, Ohio. The Maumee watershed is the largest
watershed of any Great Lakes river with 8,316 square miles. The majority of the watershed is
cultivated crop land, mostly corn and soybeans, though concentrated areas of pasture are located in
the northwestern and southeastern areas of the watershed.