Development of an ultrasensitive chemically modified carbon paste electrode for selective determination trace amount of sulfate ion

Abstract

A recently synthesized Schiff base complex of nickel ion was examined to investigate its potential to act as an ion carrier in carbon paste matrix. The carbon paste electrode (CPE) modified with the Schiff base complex represents a Nernstian slope of 29.7 mV/decade for sulfate ion through a broad concentration range of 7.5 × 10-9 – 1.5 × 10-3 M and a trace detection limit of 5.0 × 10-9 M. The CPE displays suitable reproducibility, appropriate lifetime (more than two months), fast response time (4 s) and excellent anti-Hofmeister selectivity versus a vast diversity of other inorganic anions and biological species. The temperature dependence of sensor potential was tested in the temperature range of 5–45 °C (temperature coefficient = 0.5 mV/◦C). The CPE is appropriate for SO42- determination in real samples such as mineral water and blood serum samples. The CPE detection limit is much better than the prior reported potentiometric sensors for the sulfate ion.