title: Determination of ascorbic acid in pharmaceutical dosage forms and urine by means of an oscillatory reaction system using the pulse perturbation technique.
abstract: A simple and reliable method for the determination of ascorbic acid (AA) is proposed and validated. It is based on potentiometric monitoring of the concentration perturbations of an oscillatory reaction system in a stable nonequilibrium stationary state close to the bifurcation point. The response of the Bray-Liebhafsky (BL) oscillatory reaction as a matrix, to the perturbation by different concentrations of AA, is followed by a Pt electrode. The linear relationship between maximal potential shift and the logarithm of the amount of AA is obtained between 0.01 and 1.0 micromol. The sensitivity of the proposed method (as the limit of detection) is 0.009 micromol and the method has excellent sample throughput (30 samples per hour). The procedure was used for AA determination in pharmaceutical formulations and urine. The results are in agreement with those obtained using the official method. Some aspects of the possible mechanism of AA action on the BL oscillating chemical system are discussed.
authors.affiliation: Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11000 Belgrade, Serbia. bimesel@eunet.yu
authors.forename: Natasa
authors.initials: N
authors.lastname: Pejić
authors.forename: Slavica
authors.initials: S
authors.lastname: Blagojević
authors.forename: Slobodan
authors.initials: S
authors.lastname: Anić
authors.forename: Ljiljana
authors.initials: L
authors.lastname: Kolar-Anić
mesh_terms: D001205:Ascorbic Acid / Q000652:urine*; D002138:Calibration; D002626:Chemistry, Pharmaceutical; D004304:Dosage Forms / Q000592:standards*; D004566:Electrodes; D006801:Humans; D010984:Platinum / Q000737:chemistry; D011199:Potentiometry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014815:Vitamins / Q000652:urine*
chemical_list: D004304:Dosage Forms; D014815:Vitamins; D010984:Platinum; D001205:Ascorbic Acid