Reflectometric determination after reduction to nitrite and reaction with Griess reagent.
Excess nitrate in wastewater can lead to contamination of groundwater and subsequent environmental problems including eutrophication— excessive growth of algae and plants— upsetting marine ecosystems.1 In addition, human consumption of excess nitrate has been linked to cancer and a blood condition called methaemoglobinaemia.2 As a result, monitoring nitrate levels is critical for both environmental and health reasons. Here we describe nitrate determination in wastewater using reflectometry and the Reflectoquant® Nitrate Test Kit.
Nitrate ions are reduced to nitrite ions by a reducing agent. In the presence of an acidic buffer, these nitrite ions react with an aromatic amine to form a diazonium salt, which in turn reacts with N-(1-naphthyl)-ethylenediamine to form a red-violet azo dye that is determined reflectometrically.
*Note: This application note pertains to RQflex® 20 and all discontinued instruments (RQflex® 10, RQflex® plus).
The sample can be analyzed in its original form.
The value [mg/l] will be stored automatically. (Please refer to the RQflex® operating instructions and the instruction for use of the Reflectoquant® Nitrate Test.)
Note: If a semi-quantitative determination is sufficient there is the possibility to use MQuant® test strips, Cat. No. 1.10020 10 - 25 - 50 - 100 - 250 - 500 mg/l NO₃⁻
Samples containing more than 500 mg/l NO3- must be diluted with distilled water. The pH must be within the range 1 - 12. If the pH is lower than 1, buffer the sample with sodium acetate; if it is greater than 12, adjust to approx. 3 - 5 with tartaric acid.