A proposed new ASTM International test method will present a means to perform nitrate analysis of water without the use of hazardous chemicals. WK27289, Test Methods for Nitrite-Nitrate in Water by Nitrate Reductase, is being developed by Subcommittee D19.05 on Inorganic Constituents in Water, part of ASTM International Committee D19 on Water.
William Lipps, business unit manager (environmental/chemical), Shimadzu, and D19 vice chairman, says that in WK27289 nitrate reductase is used to reduce nitrate to nitrite and the nitrite is measured colorimetrically. In addition, nitrate reductase replaces cadmium, a toxic heavy metal, or hydrazine, which is explosive and a carcinogen, making the new method a green chemistry. .
According to Lipps, the proposed reductase method is well adapted to discrete analyzers, a new type of instrument that can be used for rapid, low cost colorimetric testing of nutrients in water.
"This proposed new standard will enable testing laboratories with discrete analyzers to eliminate cadmium reduction methods with a more reliable means to measure nitrate," says Lipps.
Lipps notes that the primary users of the proposed standard, once it has been approved, will be testing laboratories. Results obtained from tests using the standard will be used to inform consumers, manufacturers and regulatory agencies whether the water tested meets certain criteria, for example a drinking water limit of 10 mg/L for nitrate nitrogen, which is regulated in drinking water and in wastewater effluents.
All interested parties are invited to join in the standards developing activities of D19.05. The subcommittee is currently seeking participation in the development of standards for total nitrogen, online nutrient analysis and analysis of fracking solutions.