Determination of Salicylate ion by Potentiometric Membrane Electrode based on Zinc Aluminium Layered Double Hydroxides-4(2,4-dichlorophenoxy)Butyrate Nanocomposites

A new salicylate ion sensor based on zinc aluminium layered double hydroxides-4(2,4-dichlorophenoxy) butyrate (Zn/Al-DPBA) nanocomposite was developed. Three plasticisers with different polarity, namely 2-nitrophenyloctylether (2-NPOE), tris(2-ethylhexyl) phosphate (TEHP) and bis(2-ethylhexyl) adipate (BEHA) were used to study the performance characteristic of the sensor. The membrane electrode having compositions 7:30:60:3 (Zn/Al-DPBA:PVC: 2-NPOE:NaTPB) exhibited excellent Nernstian slope of 58.8 ± 1.0 mV/decade in the concentration range of 1.0 x 10-5 to 1.0 x 10-1 M. It had a detection limit of 3.9 x 10-6 M and was able to give a constant potential response in the pH range of 4.0 to 12.0 at 25 ± 1 °C. The proposed sensor was easy to develop, low cost, showed fast response time (within 11-35 s) and can be used up to 4 months without any divergence in potential. The electrode was used for the determination of salicylate in pharmaceutical samples and the results were comparable with those obtained with high performance liquid chromatography method.