engleski

The electrochemical study of gallic acid in calcium oxalate system

Gallic acid (3, 4, 5-trihydroxybenzoic acid) is a secondary polyphenolic metabolite and natural antioxidant mostly found in plants and foodstuff (e.g. strawberry, blueberry, plums, walnut, tea etc.). It shows antioxidative, anticancer and antibacterial activity [1]. Gallic acid is often used in pharmaceutical industry and herbal medicine as well as food supplement [2]. It can also be used as a potential inhibitor of calcium oxalate precipitation [3]. The main goal of our study was to use voltammetric methods for detection of gallic acid in calcium oxalate system. Calcium oxalate was prepared by spontaneous precipitation after mixing calcium solution and oxalate solution in the presence of gallic acid as additive. Calcium oxalate precipitates and calcium oxalate supernatant solution were isolated for electrochemical detection of gallic acid. Electrochemical measurements were conducted in a three electrode voltammetric cell: working glassy carbon electrode, counter electrode platinum wire and Ag/AgCl reference electrode in a phosphate buffer at three different pH values (pH = 5.8, 6.5 and 7.5). The system was purged with high purity argon before each measurement. Differential pulse voltammetry was used to detect gallic acid in calcium oxalate supernatant solution. Measurements in model systems (only gallic acid solution) revealed linear response in a concentration range from 80 mol dm-3 to 1.75 mmol dm-3. The obtained results indicated adsorption/incorporation of gallic acid in the calcium oxalate precipitates, regardless of the pH values. Cyclic voltammetry was used to detect interactions between gallic acid and calcium oxalate precipitates.

gallic acid ; calcium oxalate ; voltammetry

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