Sustainable Nitrate Determination earns Standard Method Status with ASTM International

ASTM International (Formerly The American Society for Testing and Materials) has added a new standard method for nitrate determination that minimises waste, protects human and environmental health, and provides fast, accurate, and reliable results.

The newly added method, ASTM D7781 – 14, Standard Test Method for Nitrite-Nitrate in Water by Nitrate Reductase, was developed by The Nitrate Elimination Company (NECi), a biotechnology company in Michigan’s Upper Peninsula.  This method can be used to determine nitrate and nitrite (as nitrogen) content in drinking water, wastewater, and surface, saline, and ground waters.  Essentially, any aqueous solution containing nitrate can be used as the sample in this method.  The Standard Method range is from 0.05 to 5.00 mg Nitrate-N per Litre, but the upper limit may be extended by precise dilution of the sample.  The lower range can be extended by using the Low Range Method which has a lower limit of 0.005 mg Nitrate-N per Litre.

The NECi nitrate test method harnesses the biological machinery of the enzyme Nitrate Reductase to catalyse the conversion of nitrate to nitrite.  Then, addition of the Griess Reagents creates an AZO dye in the sample to produce a shade of pink.  This is then determined colorimetrically using a spectrophotometer measuring absorbance at 540 ±20nm.  By using a nitrate standard curve and a spreadsheet program or statistics package, samples may be accurately determined for precise nitrate content.

This method is suited and optimised for use in automated laboratory equipment such as discrete analysers, automated microplate readers, and machines measuring NADH disappearance.  It has been adapted to easy to use nitrate test kits that produce results within 30 minutes.  They are designed to test tap water, salt water, wastewater, agricultural runoff, water from environmental sources, soil, plant, and dry animal feed extracts, or any aqueous sample.  NECi also offers custom reagent packs and test kits for a broad range of applications.