In the U.S., water quality is monitored by the Safe Drinking Water Act (SDWA) and the Clean Water Act (CWA) and the U.S. Environmental Protection Agency (EPA) is responsible for setting the standards and methods for testing water to ensure its quality. In July 2016, the SDWA office of the EPA published a list of Alternate Test Protocols (ATP) in the Federal Register. With this action, they approved 16 alternate test methods as part of 40 CFR part 141 that could be used to measure the levels of contaminants such as free chlorine, total organic carbon, turbidity, copper, nitrate, and orthophosphate in drinking water. This allowed laboratories access to new techniques that could reduce monitoring costs while still maintaining public health standards.
One of these alternate tests was the Nitrate Elimination Company, Inc. (NECi) Method for Nitrate Reductase Nitrate-Nitrogen Analysis of Drinking Water. Nitrate is one of 16 inorganic ions on the EPA’s primary contaminant list and the presence of too much nitrate in drinking water can be harmful to both humans and livestock. The NECi method uses an enzyme as an environmentally friendly alternative to the established use of toxic cadmium reduction of nitrate to nitrite. In addition, this new method requires only a fraction of the previous sample volume and measures the sample colorimetrically at 540 nm. Validation studies, which included an inter-laboratory study with method comparison to EPA method 353.2, were conducted on three different finished drinking water matrices. The nitrate reductase method measured precision, accuracy and sensitivity against varying concentrations of nitrate standards and was found to be comparable to EPA method 353.2. Discrete photometric analyzers like the Thermo Scientific™ Gallery™ Analyzers provide excellent analytical performance for colorimetric, enzymatic and electrochemical measurements in a compact, tabletop design for water testing, enabling laboratories to measure multiple analytes simultaneously while reducing total analysis time.