Determination of Ascorbic Acid with Wells-Dawson Type Molybdophosphate in Sequential Injection System

Abstract

Two-electron reduced heteropolyblue is formed very fast at pH 3.75–4.75 in the reaction between Dawson-type molybdophosphate HPA and ascorbic acid (AsA) (ϵ⁸¹⁴ = 1.15 × 10⁴ L · mol⁻¹ cm⁻¹). Simple, fast, and direct SIA method for AsA determination was developed. Under found optimal conditions, linear calibration curve was obtained over the range 3 × 10⁻⁶–3.5 × 10⁻⁴ mol L⁻¹ AsA, and detection limit (3 s) was 1 × 10⁻⁶ mol L⁻¹. The proposed SIA method has high sample throughput of 60 h⁻¹ and small reagent consumption. The procedure was applied to the analysis of pharmaceuticals and juices.

Keywords:

• Ascorbic acid
• Dawson heteropolymolybdate
• Fruit juice
• Pharmaceuticals
• Sequential injection analysis

Acknowledgments

This paper was submitted as part of a Special Issue on Flow Injection Analysis.

P. Solich and H. Sklenářová gratefully acknowledge financial support of the Czech Ministry of Education, MSM 0021620822.

Notes

^a highest studied concentration of the interferent.

^a citric acid content is between 6 and 17 g L⁻¹(Penniston et al. 2008).

^b ordinary content of AsA in fresh juice (Nagy 1980).

^c citric acid content is about 48 g L⁻¹(Penniston et al. 2008).