Development of a rotary disc voltammetric sensor system for semi-continuous and on-site measurements of Pb(II)

Atomic absorption spectrometry and inductively coupled plasma-mass spectrometry are widely used for determination of heavy metals due to their low detection limits. However, they are not applicable to on-site measurements of heavy metals as bulky equipment, and highly skilled laboratory staffs are needed as well. In this study, a novel analytical method using a rotary disc voltammetric (RDV) sensor has been successfully designed, fabricated and characterized for semi-continuous and on-site measurements of trace levels of Pb(II) in non-deoxygenating solutions. The square wave anodic stripping voltammetry was used to improve the sensitivity of the Pb(II) detection level with less than 10 nM (2 μg L−1). The RDV sensor has 24-sensing holes to measure concentrations of Pb(II) semi-continuously at sampling sites. Each sensing hole consists of a silver working electrode, an integrated silver counter, and a quasi-reference electrode, which requires only a small amount of samples (<30 μL) for measurement of Pb(II) without disturbing and/or clogging the sensing environment. In addition, the RDV sensor showed a correlation coefficient of 0.998 for the Pb(II) concentration range of 10 nM-10 μM at the deposition time of 180 s and its low detection limit was 6.19 nM (1.3 μg L−1). These results indicated that the advanced monitoring technique using a RDV sensor might provide environmental engineers with a reliable way for semi-continuous and on-site measurements of Pb(II).