PNNL

Abstract

Mercury-free sensors for lead (Pb2+) assay based on chemical modification of screen-printed carbon electrodes (SPCEs) with acetamide phosphonic acid self-assembled monoloyer on mesoporous support (Ac-Phos SAMMS) have been developed. The preconcentration of Pb2+ at SAMMS-based sensors utilize the binding affinity of the acetamide phosphonic acid and Pb2+, which can be accomplished at open circuit potential without electrolyte and solution degassing. Due to the strong covalent bonding of the functional groups on SAMMS, the SAMMS based sensors with a built-in 3 electrode system can be reused for tens of measurements with minimal degradation, enabling the establishment of the calibration curve and lowering the costs. Linear calibration curve was found in the range of 0 to at least 100 ppb Pb2+ after 5 minutes of preconcentration. The detection limit was calculated from 3S/N to be 1 ppb of Pb2+. Reproducibilty (%RSD) was found to be 5% for a single sensor (6 measurements) and 10% for 5 sensors. The reproducibility can be improved through the precision of manufacturing of the sensors, in which SAMMS modification can be done in-situ, increasing the user-friendliness of the sensors. Cadmium, lead, and copper can also be detected simultaneously at the SAMMS screen-printed sensors.