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Automatic potentiometric flow titration procedure for ascorbic acid determination in pharmaceutical formulations.

Ana Paula S Paim·Cristina M N V Almeida·Boaventura F Reis·Rui A S Lapa·Elias A G Zagatto·José L F Costa Lima
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Abstract

A flow procedure for the determination of ascorbic acid in pharmaceutical formulations exploiting potentiometric titration is described. The method is based on the reduction of IO3- by ascorbic acid and the detection was carried out employing a flow-through ion selective electrode for iodide. The flow network controlled by a microcomputer was designed to implement multicommutation for ease of operation and robustness. The titration system allowed the determination of ascorbic acid in pharmaceutical formulations with concentrations ranging from 7.5 to 15.0 mmol l(-1). No significant differences at the 95% confidence level were observed in comparison with results obtained by a manual procedure. Merit figures of results such as a relative standard deviation of 1.0% (n=6) and a reagent consumption of 21.4 mg IO3- per determination were obtained.

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Ascorbic AcidChemistry, PharmaceuticalFree Radical ScavengersPotentiometryJournal ArticleResearch Support, Non-U.S. Gov't

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Ana Paula S Paim, Cristina M N V Almeida, Boaventura F Reis, Rui A S Lapa, Elias A G Zagatto, José L F Costa Lima. 2002-06-15. Automatic potentiometric flow titration procedure for ascorbic acid determination in pharmaceutical formulations.. https://doi.org/10.1016/s0731-7085(02)00018-3

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Ascorbic acid (AsA) is an essential nutritional component and powerful antioxidant in vegetables, and in plants, AsA levels are regulated by light. AsA levels in the leaves of Chinese chive (Allium tuberosum Rottler ex Spr), a popular vegetable, are poorly understood. Thus, this study was performed to assess the influence of light on AsA biosynthesis in chive and select related genes (AtuGGP1 and AtuGME1); in addition, bioinformatic analyses and gene expression level assays were performed. The biological information obtained for AtuGGP1 and AtuGME1 was analysed with several tools, including NCBI, DNAMAN, and MEGA11. After different light treatments were performed, the Chive AsA content and AtuGGP1 and AtuGME1 expression levels were determined. These results suggest that 1) compared with natural light, continuous darkness inhibited AsA synthesis in chives. 2) The amino acid sequences of AtuGGP1 and AtuGME1 are very similar to those of other plants. 3) The trends observed for the expression levels of AtuGGP1 and AtuGME1 were consistent with the AsA content observed in chives. Hence, we speculated that light controls AsA biosynthesis in chives by regulating AtuGGP1 and AtuGME1 expression. This study provided impactful and informative evidence regarding the functions of GGP and GME in chives.

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