Simultaneous Measurements of Eight Oxyanions Using High Capacity Diffusive Gradients in Thin Films (Zr Oxide DGT) with a High Efficiency Elution Procedure.
A zirconium oxide binding gel based diffusive gradients in thin films (Zr oxide DGT) was developed for simultaneous measurements of P(V) As(V) Cr(VI) Mo(VI) Sb(V) Se(VI) V(V) and W(VI) All of the oxyanions were rapidly bound to Zr oxide gel with differences in binding affinity. The eight bound oxyanions were successfully recovered by one step elution using a mild reagent of 0.2 M NaOH 0.5 M H2O2 by overcoming the problems in analyses of the oxyanions. The optimized elution time was reduced to 3 5 h from 24 48 h required by other DGTs. DGT uptakes of all the oxyanions were independent of pH (4.42 8.45) and ionic strength (0.1 500 mM) The DGT capacities for six oxyanions detected in multioxyanion solution were only 0.19 to 0.35 times of those detected in single oxyanion solution, reflecting a strong competition among the oxyanions during DGT uptake. Except for Se(VI) in seawater, Zr oxide DGT accurately measured all of the oxyanions in synthetic freshwater and seawater, with the capacities ~29 to >2397 times and ~7.5 to 232 times those of two commonly used DGTs (Metsorb and precipitated ferrihydrite (PF) DGTs) in freshwater and seawater, respectively. Measurements by Zr oxide DGT in contaminated sediments were in agreement with only two oxyanions with the two commonly used DGTs; the two DGTs accumulated less or no mass of other oxyanions. This study demonstrates significant advantage of Zr oxide DGT over the other DGTs in simultaneous measurements of the eight oxyanions due to the former's high capacity and a wide tolerance to environmental interferences, together with a high efficiency in elution.
Environmental science technology