Determination of Inorganic Nitrate in Serum and Urine by a Kinetic Cadmium-Reduction Method

Abstract

Nitrate in serum and urine was assayed by a modification of the cadmium-reduction method; the nitrite produced was determined by diazotization of sulfanilamide and coupling to naphthylethylene diamine. After samples were deproteinized with Somogyi reagent, the nitrate was reduced by Cu-coated Cd in glycine buffer at pH 9.7 (2.5 to 3 g of Cd granules for a 4-mL reaction mixture). The reduction followed pseudo-first-order reaction kinetics, a convenient time interval for assay being 75 to 90 min. Maximum reduction (85%) occurred at about 2 h. Detection limits in urine or serum were 2 to 250 µmol/L. This method does not require the reaction to go to completion, does not require expensive reagents or equipment, and can assay several samples simultaneously. Repeated assays of two serum pools gave CVs of 9.0% and 4.7% for nitrate concentrations of 31.4 and 80.2 µmol/L, nitrate was 1704.0 ± 1294 (SD) µmol/L (n = 21) in untimed normal urine, 81.8 ± 50.1 µmol/L in serum of 38 renal dialysis patients, and 51.2 ± 26.4 µmol/L in serum of 38 controls.

Cardioprotective Effects of Nigella sativa Oil on Cyclosporine A‐Induced Cardiotoxicity in Rats

“…The resulting equation was then used to calculate the unknown sample concentrations. Results were expressed as nmol/g wet tissue [24].…”

Lipid peroxidation and antioxidant status in lichen planus

“…Total nitrite (nitrate + nitrite) was measured using a spectrophotometer at 545 nm after conversion of nitrate to nitrite by copperized cadmium granules. 6 A standard curve was established with a set of serial dilutions (10 )8 )10 )3 mol ⁄ L) of sodium nitrite. Linear regression was carried out using the peak area from the nitrite standard.…”

Protective role of carnitine in breast cancer via decreasing arginase activity and increasing nitric oxide

“…Nitrite and nitrate are the primary oxidation products of NO subsequent to its reaction with oxygen and, therefore, the nitrite/nitrate concentrations in tumour tissue were used as indicator of NO synthesis. Quantification of nitrate and nitrite was based on the Griess reaction, in which a chromophore with a strong absorbance at 545 nm is formed by the reaction of nitrite with a mixture of naphthylethylenediamine and sulphanilamide (Cortas and Wakid, 1990). Samples were de-proteinised with Somogyi reagent.…”