2714100 Total Nitrogen Cuvette Test, 10-150 mg/L N

16 mm Test 'N Tube Cuvette test measures 10-150 mg/L N in water, wastewater and other liquids. The product uses persulphate digestion method (10072). Article 2714100 can be used to conduct evaluation of 25-50 tests. The product may be evaluated using DR900 colorimeter only.

Procedure for N measurement

Pour the content of Total Nitrogen (TN) Persulfate Reagent Powder Pillow to each vial. Prepare the sample by pipetting 0.5 mL of sample in the vial. Prepare the blank by pouring 0.5 mL of deionized nitrogen-free water in the blank vial. After that close vials, shake the vial content and put in the reactor for 30 minutes. Put the content of TN Reagent A Powder Pillow and TN Reagent B Powder Pillow to each vial. It is required to shake and use the instrument timer after adding reagents (see manual). Add 2 mL of the prepared sample into the TN Reagent C vial. Pipet 2 mL of the prepared blank in the second TN Reagent C vial. Insert the stirred blank vial in the cell holder of the colorimeter and push ZERO. Remove the blank vial and evaluate the sample vial.

Summary of method

Alkaline persulfate digestion converts nitrogen to nitrate. Sodium metabisulfite is added after the digestion to eliminate halogen oxide interferences. Nitrate enters into reaction with chromotropic acid under strongly acidic conditions forming yellow complex that must be evaluated photometrically.

Sample preparation

For short-term sample conservation, the pH of the collected sample is required to be 3-7 pH. For long-term preservation, the water and wastewater sample must be stored at temperature of -18 °C. The sample should be kept in the glass, polyethylene and borosilicate glass container. The recommended storage temperature of the product is from 10 °C to 25 °C.