Selective determination of isoniazid using bentonite clay modified electrodes

Fe(dmbpy)32 + (where dmbpy is 4,4′-dimethyl-2,2′-bipyridine) was immobilized by ion-exchange in a bentonite clay film coating on a glassy carbon electrode. Cyclic voltammetry characteristics of the immobilized Fe(dmbpy)32 + were stable and reproducible corresponding to the Fe(dmbpy)32 +/3 + redox process. In the presence of isoniazid (IZ), the electrogenerated in film Fe(dmbpy)33 + oxidized IZ efficiently producing large anodic current. This current was linearly proportional to the IZ concentration in the solution. The process was described by an EC' electrocatalysis mechanism allowing for sensitive determination of IZ with a wide linear dynamic concentration range of 10.0 μM to 10.0 mM. The electrode was tested for its analytical suitability and possible discrimination of interferences by determining IZ in a commercially available pharmaceutical product. The paper reports on a simple, cheap, and easy to fabricate chronoamperometric chemical sensor for determination of IZ. Kinetic parameters, such as the catalytic rate constant (2.3 × 103 M− 1 s− 1) and diffusion coefficient of IZ (5.42 × 10− 5 cm2 s− 1), were determined using CV, chronoamperometry, and chronocoulometry.