Determination of Ni2+ in Waters with Sodium Poly(aspartic acid) as a Binding Phase in Diffusive Gradients in Thin Films

Abstract

The technique of diffusive gradients in thin films (DGT) for the measurement of Ni2+ in waters was developed using sodium poly(aspartic acid) (PASP) solution as the liquid binding phase in the liquid-type DGT devices (PASP DGT). The Ni2+ uptake of PASP DGT increased linearly with time (r2 = 0.9990) with a DGT-labile fraction (Ψ) of 98.04 ± 1.76% in synthetic solution. The Ψ values of Ni2+ were measured in spiked river water (37.82 ± 2.79%) and spiked domestic wastewater (28.46 ± 1.87%). The stability constant (log K) of PASP–Ni was 8.56, indicating that PASP can coordinate strongly to Ni2+. The binding capacity of PASP DGT decreased with increase of ionic strength, whereas it remained fairly constant in the pH range 4–9. The results show that PASP can be used as a binding phase in the liquid-type DGT device for the measurement of Ni2+ in waters.

Measurement of Dissolved Reactive Phosphorus in Water with Polyquaternary Ammonium Salt as a Binding Agent in Diffusive Gradients in Thin-Films Technique

“…However, polyacrylamide hydrogel has some disadvantages, such as a weak mechanical resistance and not a well-defined gel structure, and the DGT method requires elution of analyte from the binding gel that may introduce analytical deviation. Li et al invented a liquid-type DGT sampler with a diffusive phase, such as a dialysis membrane, and a liquid binding phase, such as poly(4-styrenesulfonate) solution, with some advantages, such as a good contact between the binding phase and the diffusive phase, ideal transportion and enrichment of analyte, a well-defined reproducible diffusive phase, and no need for the elution of analyte accumulated in the binding phase. , Sodium polyacrylate solution, , poly(vinyl alcohol) solution, thiol–poly(vinyl alcohol) solution, poly(aspartic acid), , and polymer-bound Schiff base have been developed as liquid binding phases recently.…”