PNNL

Abstract

Mercury-free sensors for europium (Eu3+) assay, based on chemical modification of screen-printed carbon electrodes (SPCEs), with self-assembled salicylamide ligands on mesoporous silica (Sal-SAMMS) have been developed. The preconcentration of Eu3+ at SAMMS-based sensors utilize the binding affinity between the salicylamide ligand and Eu3+, which can be accomplished at open circuit potential without electrolyte and solution degassing. This was followed by the anodic stripping voltammetric Eu detection in a new medium. Due to the strong covalent bonding of the functional groups on mesoporous silica, 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 response was found in the range of 75 to at least 500 ppb Eu3+ after a 5 minute preconcentration period. The detection limit was 10 ppb after a 10 minute preconcentration, and this limit can be improved with increased preconcentration time. Reproducibility (%R.S.D) of 100 ppb Eu2+ was 10% for a single sensor (5 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.