Rapid and Reliable HPLC Method for the Determination of Vitamin C in Pharmaceutical Samples

Purpose: To develop and validate an accurate, sensitive and reproducible high performance liquid chromatographic (HPLC) method for the quantitation of vitamin C in pharmaceutical samples.Method: The drug and the standard were eluted from Superspher RP-18 (250 mm x 4.6 mm, 10ìm particle size) at 20 0C. The mobile phase was prepared by carefully adding acetic acid (500 ml) to 1.5g of 1-hexanesulfonic acid sodium salt and mixing well (pH 2.6). The flow rate was 0.7 mL min-1. UV detector, set at 280 nm, was used to monitor the effluent.Results: Each analysis required no longer than 4 min. The limit of quantitation was 1.95 ìg mL-1. Recovery (%) for different concentrations ranged from 99.58 to 101.93.Conclusion: The simplicity of this low-cost, rapid technique and its high specificity to ascorbic acid, even in the presence of a variety of excipients, demonstrate that this HPLC method would be particularlysuitable for the determination of ascorbic acid in the investigated preparations as well as other similar pharmaceutical/veterinary formulations without prior sample preparation

A New Kinetic Spectrophotometric Method for Total Polyphenols Determination in White Wines

This paper describes a new, simple and sensitive catalytic kinetic spectrophotometric method for the determination of total polyphenols in white wines. The method was based on the catalytic effect of Cu(II) on the oxidation of phenolic compounds by H2O2 in acid media. The reaction was followed spectrophotometrically by measuring the increase in absorbance of oxidation products at 420 nm. Under optimal experimental conditions, a differential variation of the tangent method was used to obtain a calibration curve over the range of 23.01–194.11 g mL–1 of phenols. The calculated detection limit (3.3S0/b) was 6.77 g mL–1 for ten replicate measurements of blank signal. The relative standard deviations for five replicate determinations on 70.0, and 170.0 gmL–1 of galic acid were 2.49 and 1.79 %, respectively. The proposed method was successfully applied for the determination of total polyphenols in white wine samples and the results were in excellent agreement with the Folin-Ciocalteau method.KEYWORDS: Kinetic-spectrophotometric method, phenolics oxidation, white wine