Fabrication of an Enhanced carbon paste Electrochemical Sensor for the Determination of Cobalt(II) Ion

Abstract

A selective sensor for Cobalt ions (Co²⁺) was developed, consisting of( 5% complex LO:(3-(2-Nitrophenylazo) -pentane-2,4-dione )  With Cobalt Ions as  Ionophore, 50.94% Graphite ,0.28 Tetra phenyl borate sodium, 43.78% Di Butyl phthalate ), the  sensor exhibited  a Nernstian response in the range ( 1.0 ˣ 10^-7 – 1.0 ˣ 10^-1 ) M . with aa Nernstian slope of (29.48±1.00) mv per decade of Cobalt Ions. In terms of technical properties, the sensor demonstrated a response time of  (10) Seconds and a lifetime exceeding 25 weeks, with a wide linear pH range of (3.0-10.0) and an operating temperature range of (15-80) ͦ C.

Selectivity coefficient calculations for the proposed sensor, using the Matched potential Methods(MPM).revealed high selectivity in the presence of various heavy and transition metal ions (Mg²⁺, Co²⁺, Zn²⁺, Cd²⁺, Pb²⁺, Fe³⁺, Na⁺, K⁺) Commonly associated with Cobalt in its ores, with a correlation coefficient (R) of (0.999), ensuring the required analytical accuracy and precision. Furthermore, the sensor was successfully applied and compared to a validated spectrophotometric method, showing no significant difference between the two methods, according to Fisher's(F) and student's (t) statical criteria, in applications to both standard and real samples.