Ammonia, UV method

Enzymatic method for the determination of ammonia (main inorganic source of Yeast Available Nitrogen -YAN). Based on the spectrophotometric measurement of NADPH consumed through the reaction, after addition of glutamate dehydrogenase (GlDH). This rapid and simple specific enzymatic method is used for the determination of ammonia (ammonium ions) in foodstuffs such as wine, fruit juice, bakery products, dairy products, egg products, meat, seafood and dietetic food, as well as in paper, fertilizer, pharmaceuticals, cosmetics, water and biological samples. Ammonia is mainly produced by microbial protein catabolism of organic material. Therefore, high concentrations of ammonia can indicate the decomposition of substances like milk, meat and seafood, being ammonia a major component of the off-flavours and odours. Ammonia also indicates the presence of faeces, urine and microorganisms in water. In the wine industry, ammonia determination is important in the calculation of yeast available nitrogen (YAN). This kit uses a glutamate dehydrogenase that is not inhibited by tannins found in grape juice and wine. However, YAN comprises three components: free ammonium ions, amino nitrogen from free amino acids and from the side chain of L-arginine. Thus, for the most accurate determination of YAN, all three components should be quantified, which is possible by using Nzytech's L-Arginine/Urea/Ammonia kit. Components: Solution 1 (2x). TEA buffer (24 mL, 0.5 M, pH 8.0) plus imidazole (200 mM), 2-oxoglutarate (40 mM) and sodium azide (0.02 % w/v) as a preservative. Store at 2 °C to 8°C.Tablets 2. 192 tablets of NADPH supplied in a plastic vial containing desiccant. Allow this container to warm to room temperature (in the presence of a desiccant if possible) before opening to remove tablets. Store desiccated at 2 °C to 8°C (Long term storage: -30 °C to -15 °C) Add 2 tablets and 0.5 mL of solution 1 per assay, including blank reaction, to a test tube and stir intermittently over 2-3 min (Solution 1+2).Suspension 3. Glutamate dehydrogenase (GlDH) is provided in 2.5 M lithium sulphate (EC 1.4.1.2, 2.2 mL, 785 U/mL). Store at 2 °C to 8°C. Swirl bottle before use.Solution 4. Ammonia standard solution (5 mL, 0.04 mg/mL) in 0.02 % (w/v) sodium azide. Store at 2 °C to 8°C. This standard should be used when there is doubt about the method accuracy. Shipping Conditions: Room Temperature. Storage Conditions: 2 °C to 8 °C. Application: Biofuel, Dairy, Feed, Fermentation, Food, Wine. Features: Detection limit: 0.07 mg/L, Range: 10-70 mg/L. Detection Method: UV Method. Analyte: Ammonia