The diffusive gradient in thin film (DGT) is an analytical method on separation and determination of phosphate. The surface analysis of gel was used in the scanning electron microscopy (SEM) that show the chemical and physical interaction in diffuse gel and oxide gel. The response of DGT device in speciation of phosphorus as H2PO- 4, HPO2- 4 and PO3- 4 showed a linear correlation between concentration and accumulation of phosphate with the concentration of 0.2 – 1.0 mgL-1. Species of H2PO- 4 give a linear correlation of 0.9792 with regression linear at y = 9.8825x - 0.0503. The HPO2- 4 give a linear correlation of 0.8872 with regression linear at y = 7.2143x - 0.7545. The species of PO3- 4 give a linear correlation of 0.9769 with regression linear at y = 7.5558x - 0.1828. The phosphorus accumulation from different speciation showed H2PO- 4 ˃ PO3- 4> HPO4 2 with accumulation was 9.6525 μg, 7.1589 μg, and 6.8783 μg, respectively. The DGT can response of phosphate with various pH at 2-12 and showed the species of phosphate as H2PO- 4, HPO2- 4 and PO3- 4. The optimum response show at the pH of 4 that shows the species of H2PO- 4. Anion interference was studied in this research including SO2- 4, NO- 3 and CO2- 3. Effect of anion sulfate, nitrate and carbonate can reduce of phosphate accumulation in DGT device in the range of anion concentration from 0.05 to 0.25 mgL-1. The interferences of NO- 4, SO2- 4, CO2- 3 at 0.25 mgL-1 can reduce of phosphate accumulation with the efficiency of 64.64 %, 25.10 %, and 7.57 %, respectively. The effect of NO- 3 ˃ SO2- 4 ˃ CO2- 3 in the accumulation of phosphate in the binding gel of DGT unit. Keywords: orthophosphate, DGT, speciation, pH, anion interferences.
- Anion interferences