Detection of Metals Using Stripping Voltammetry on 3D Printed Electrodes

The current detection methods for determining the concentrations of metals (AAS and ICP) are problematic as they are very expensive instruments and often require pretreatment of samples before they can be measured. With the technique discussed today, stripping voltammetry, only two instruments are required: a 3D printer and potentiostat, which are both significantly less expensive than the aforementioned instruments. Here, we employ monolithic 3D printed fluidic devices for quantifying lead, cadmium, mercury, and copper. We employ fluidic devices as they can potentially be more sensitive than commercially developed electrodes and can thus detect lower levels of metal analyte concentrations. Coating the electrode in bismuth has been found to result in better peak-to-peak separation for lead and cadmium in solution, while mercury and copper can be analyzed without pretreatment. Initially, both the voltage and time of the bismuth and metal depositions were optimized to provide the highest sensitivity. Once these parameters were determined, a study involving mercury in dilute hydrochloric acid was conducted, and excellent linearity (R2 = 0.9971) and limits of detection below the EPA limit for drinking water (~20 nM) were observed. Another experiment was run with cadmium and lead in an acetate buffer. For both lead and cadmium, concentrations below the set EPA limit were able to be detected: 15 ppb for lead and 5 ppb for cadmium. Currently, a 3D printed flow device is used, which can conduct more sensitive and precise measurements. Overall, these results are very promising, as it indicates that these electrodes can potentially test multiple analyte metal concentrations in tap water matrices.