LaMotte SMART3 Colorimeter User Manual
Page 216
APPLICATION:
swimming pools, drinking water, surface and saline
waters
RANGE:
0.00 – 80.0 ppm nitrate
MDL:
2 ppm
METHOD:
Zinc is used to reduce nitrate to nitrite. The nitrite that
was originally present, plus the reduced nitrate, reacts
with chromotropic acid to form a red color in proportion
to the amount of nitrite in the sample.
SAMPLE HANDLING
& PRESERVATION:
Analysis should be made as soon as possible. If
analysis cannot be made within 24 hours, the sample
should be refrigerated at 4°C. When samples must be
stored for more than 24 hours, add 2 mL of concentrated
sulfuric acid per liter of sample. For best results, the
analysis for nitrate should be determined at temperatures
between 20°C and 25°C.
INTERFERENCES:
Nitrite interferes at all concentrations. Strong oxidizing
and reducing substances interfere. Low results might be
obtained for samples that contain high concentrations of
copper and iron.
NITRATE, UDV
SMART3 Test Procedures 11,11
Test P
rocedures