Amperometric Detection of Hexavalent Chromium with L-DOPA Modified Screen Printed Electrode

Hexavalent chromium enters the environment through several anthropogenic activities and it is highly toxic and carcinogenic. Conventional analytical methods for determination of chromium ions are tedious, time consuming and expensive. Electrochemical sensor may serve the purpose due to its relative simplicity, selectivity, low-cost and fast response time. In the present study, we have used L-DOPA (L-3,4-dihydroxyphenylalanine) modified disposable screen-printed electrodes for development of amperometric sensor for measurement of hexavalent chromium. L-DOPA reduces hexavalent chromium to trivalent chromium and this redox reaction was exploited to develop the sensor. The proposed sensor showed linear response in the range 10-125 mu g/L and detection limit was determined to be 6.01 mu g/L. The repeatability of the amperometric sensor, evaluated in terms of relative standard deviation was 4.24% for five set of experiments. The amperometric sensor showed maximum activity pH 7.0 at 20 +/- 2 degrees C. No interference was observed in the presence of metal ions e.g., cobalt, cadmium, arsenic, iron etc. The proposed sensor was used for measuring chromium concentration in wastewater samples. The results were comparable to those obtained by atomic absorption spectrophotometer.