Analytical Sciences

Abstract − Analytical Sciences, 24(12), 1569 (2008).

Simple and Sensitive Electroanalytical Method for the Determination of Ascorbic Acid in Urine Samples Using Measurements in an Aqueous Cationic Micellar Medium
Alaécio Pinheiro dos REIS,* César Ricardo Teixeira TARLEY,** Lucilene Dornelles MELLO,* and Lauro Tatsuo KUBOTA*
* Instituto de Química, UNICAMP, P. O. Box 6154, Campinas, SP, 13083-970, Brazil
** Departamento de Ciências Exatas, Unifal-MG, Alfenas, MG, 37130-000, Brazil
An electroanalytical study for the amperometric determination of ascorbic acid (AA) in a human urine sample at a bare glassy carbon electrode using the CPC (cetylpyridinium chloride) surfactant is described. Under the optimized conditions of Epa, Ipa, CPC concentration and pH, the oxidation peak potential of the AA shifts towards a less positive potential, and the peak current increase in a significant way in the presence of the surfactant. Under the best conditions, the method provided a linear calibration curve to AA in a 0.1 mol L-1 phosphate buffer solution (pH 7.0) in the concentration range from 5.0 × 10-7 up to 4.3 × 10-4 mol L-1, with a detection limit of 2.0 × 10-7 mol L-1 and a high correlation coefficient (r = 0.9996). The recovery test presented values of 98 - 105%, suggesting a great potential of the proposed method for AA determination in complex samples, such as urine.