An oxalate selective electrode based on modified PVC-membrane with tetra-butylammonium - Clinoptilolite nanoparticles

A modified PVC-membrane electrode with tetra-butylammonium bromide Clinoptilolite nano-particles (TBA-NCP) showed good Nernstian slope (29.9 +/- 0.6 mV per decade of oxalate concentration) in concentration range of 3.1 x 10(-7) -8.3 x 10(-1) mol L-1 with a detection limit of 1.5 x 10(-7) mol L-1 The best performance was obtained with a membrane composition of 31.5% PVC, 62.5% DOP and 6% TBA-NCP in the temperature range of 20-35 degrees C and the pH range of 4-9. The fast response time and good reproducibility over a period of 3 months are other characteristics of the sensor. The proposed electrode was successfully used as an indicator electrode in titration of oxalate ions with CaCl2 solution. The proposed electrode was also used in direct potentiometric determination of oxalate in many real samples such as: mushroom, black and green tea, spinach and beet. (C) 2015 Elsevier B.V. All rights reserved.