Design and Synthesis of the Poly Vinyl Chloride (PVC) Membrane for Fe(III) Ion Selective Electrode (ISE) Based on Ester Modified Humic Acid (EHA) as an Ionophore

Design and synthesis of the poly vinyl chloride (PVC) membrane as Fe(III) ion selective electrode (ISE) sensor based on EHA ionophore as an excellent sensory molecule for monitoring Fe(III) in the sample solution had been done. Simple and efficient EHA was made by condensation of carboxylic acid HA with ethanol and sulfuric acid as catalist. PVC membrane was prepared by mixed all component such as PVC powder, EHA, plasticizer (o-NPOE and DOP) and anion lipophilic (Sodium-TPB and oleic acid) with a total weight of 100 mg and dissolved in 1 mL of dry THF. The electrode membrane responses showed that the electrodes were highly selective to ion Fe3+ at pH 3 with response time of ±50 seconds. The dynamic range of the membrane ISE sensor was 10-1–10-7 M with the value of Nernst factor was ±19 mV per decade. The membrane electrode can be used for at least 5 weeks. The analytical results of Fe(III) measurement showed good confirmity with reference method (AAS), suggesting that the developed analytical tool could be used to measure and monitor Fe(III) in the real water samples.