Disposable electrochemical sensor for determination of nitroaromatic compounds by a single-run approach

Environmental and security applications have generated major demands for effective field-deployable tools for detecting nitroaromatic compounds, such as chloramphenicol (an antibiotic), parathion (an organophosphate nerve agent), and TNT (2,4,6-trinitrotoluene, an explosive) in a fast, simple, sensitive, reliable, and cost-effective manner. We report here a single-run approach for such a purpose. The reduction potential of different nitroaromatic compounds was found to systematically shift with the substituent group at an electrochemically preanodized screen-printed carbon electrode. The preanodization treatment makes the peak sharp and hence provides a precise way to identify the substituent effect on nitroaromatic compounds. By using potential shifts as analytical characteristics of nitroaromatic compounds, a suitable internal standard can be chosen based on the criteria of well-separated peak potential and rarely found in the real sample of interest. Simply by measuring the ratio of peak currents between analytes of interest and internal standard, the analysis can be done in a single-run measurement. Both the matrix effect and the variation of electrode during the preparation process can be canceled out in this approach and thus allows for a high-precision analysis. Just by placing a 20-microL drop on a single-use amperometric sensor strip incorporating a three-electrode configuration is enough for rapid and sensitive detection of nitroaromatic compounds by square-wave voltammetry. For example, the linear detection range can be up to 100 microM with a detection limit of 0.42 microM (S/N = 3) in the detection of chloramphenicol. This approach was successfully demonstrated in real sample analysis to verify the applicability of the method. The promising performances open new possibilities for rapid determination of nitroaromatic compounds in environmental and biological samples.