Development of cerium oxide-based diffusive gradients in thin films technique for in-situ measurement of dissolved inorganic arsenic in waters

Abstract A diffusive gradients in thin films (DGT) method using a new high-capacity cerium oxide (CeO 2 ) binding gel, for the first time, was developed for measuring dissolved inorganic arsenic in freshwater and seawater. The capacities of the new CeO 2 binding gel were 682 μg and 375 μg for As III and As V , respectively. The masses of As III and As V accumulated by CeO 2 -DGT device increased linearly with time and agreed well with the theoretical value calculated by DGT equation. The arsenic accumulation by CeO 2 -DGT was independent of pH (4.05–9.04) and ionic strength (0.1–750 mM), and common anions including CO 3 2− , SO 4 2− , Cl − and PO 4 3− had no obvious interference. CeO 2 -DGT showed excellent long-term deployment performance in freshwater and synthetic seawater. Field trials with CeO 2 -DGT achieved successfully the time-weighted-average concentrations of total inorganic arsenic in reservoir water (1.38 ± 0.09 μg/L) and coastal seawater (0.45 ± 0.06 μg/L). The results were comparable to those measured by grab sampling. The proposed method was reliable and robust for in-situ measurements of dissolved inorganic arsenic in environmental waters.