Simple, Sensitive, and Rapid Voltammetric Detection of Alloxan on Glassy Carbon Electrodes

Alloxan is a chemical generally administered to rats to induce diabetes mellitus, and pharmaceutical industries test the efficacy of their diabetic products on these rats. Alloxan is in a redox cycle with dialuric acid; hence, direct estimation of alloxan may not represent the actual concentration of the same in a given matrix. Also, in recent times, alloxan is added to food materials, especially to the all-purpose flour (maida) to bring softness and white color to the flour. Hence, consumption of food items made from such flour could induce diabetic mellitus in individuals, making it imperative to develop an accurate estimation of alloxan in food items. Herein, a voltammetric-based technique is developed to quantify the alloxan in refined wheat flour (maida) using an unmodified glassy carbon electrode (GCE). The electrochemical method offers rapid sensing while the use of an unmodified GCE surface offers repeatability and reproducibility between measurements. First, alloxan is converted to its stable adduct alloxazine by the reaction with o-phenylenediamine. The alloxazine adduct is electrochemically active, and the concentration of alloxan is estimated as a function of alloxazine formed using the voltammetric technique. The common shortfall in alloxan detection mainly involves its short half-life (similar to a minute) whereas the alloxazine adduct formed is stable over a period of time. Using the current approach, alloxan concentration ranging from 10 to 600 mu M is detected with a sensitivity of 0.0116 mu A/mu M. A low limit of detection of 1.95 mu M with a precision of 1.2% is achieved using the above method. Real sample analysis revealed the presence of alloxan in all-purpose flour (maida-refined wheat flour) and bread purchased from the local market to the values of 35.76 and 25.03 mu M, respectively. The same is confirmed using the gold-standard colorimetric technique.