ascorbic-acid and sulfosalicylic-acid

Ascorbic acid in medicine was determined by fading spectrophotometric method, based on Fe3+ reduced into Fe2+ by ascorbic acid and reacting on sulfosalicylic acid. The results obtained were in agreement with those of Chinese pharmacopoeia's method and background correction method.

Topics: Ascorbic Acid; Benzenesulfonates; Pharmaceutical Preparations; Salicylates; Spectrophotometry, Ultraviolet

We use oxalate oxidase from barley seedlings for the colorimetric determination of oxalate in plasma. The oxalate is converted to hydrogen peroxide, which, in the presence of peroxidase, is detected by a Trinder-like chromogenic system. Optimization of the assay, including deproteinization and elimination of interferences from reducing substrates, is described. Ascorbate additions (200 mumol/L) did not affect oxalate concentration in plasma, even after long frozen storage. Mean analytical recovery of oxalate averaged 102% +/- 6.9%, imprecision (CV) at 2.0 mumol/L was 7.2%, and the lower limit of quantification (CV = 20%) was 0.6 mumol/L. Results correlated well with those by chromatography (r = 0.999, Sy/x = 0.29 mumol/L, n = 32, range for x, y = 0-140 mumol/L). Plasma oxalate concentrations measured in 32 healthy subjects ranged from 0.6 to 2.9 mumol/L (mean 1.28, SD 0.71 mumol/L), which agrees with those measurable by using indirect radioisotopic dilution methods. Patients with primary hyperoxaluria and chronic renal failure exhibited markedly greater plasma concentrations of oxalate.

Topics: Adolescent; Adsorption; Adult; Ascorbic Acid; Benzenesulfonates; Blood Proteins; Charcoal; Child; Chromogenic Compounds; Colorimetry; Drug Stability; Female; Freezing; Hordeum; Humans; Hyperoxaluria; Kidney Failure, Chronic; Male; Oxalates; Oxalic Acid; Oxidoreductases; Quality Control; Reference Values; Salicylates; Sensitivity and Specificity