Diffusion Coefficient of Phosphate Ion in Citric Acid-Agarose Gel Used in Diffusive Gradient in Thin Films (DGT) Passive Sampler

In this research, the diffusion coefficient of phosphate ions in agarose-citric acid diffusive gel has been studied. The layer was prepared by mixing 1.5% agarose solution with addition citric solutions at various concentration. casted between two glass plates which were separated using a spacer 0.1 cm thickness and clamped together three sides. Gel formed for 15 minutes an oven 40oC. then calculated Fick's First law formula. that produced 0.45% absorbed more water during immersion 3 hours facilitating diffusion. Swelling degree gels not affected storing condition either or NaNO3 M. Coefficient 1.009×10-7 cm2s-1, less than pure 1.367×10-7 cm2s-1. is ionic strength solution. Phosphate higher 2 mgL-1 nitrate. Increasing causes lower because electrostatic attractive repulsive force