Voltammetric Determination of Codeine on Glassy Carbon Electrode Modified with Nafion/MWCNTs

Abstract

A glassy carbon electrode modified with a Nafion/MWCNTs composite is shown to enable the determination of codeine using differential pulse voltammetry in phosphate buffer of pH 3.0. At a preconcentration time of 15 s, the calibration graph is linear in the 0.5 µ M (0.15 mg·L −1 ) to 15 µ M (4.5 mg·L −1 ) concentration range with a correlation coefficient of 0.998. The detection limit at a preconcentration time of 120 s is as low as 4.5 μ g·L −1 . The repeatability of the method at a 0.6 μ g·L −1 concentration level, expressed as the RSD, is 3.7% (forn=5). The method was successfully applied and validated by analyzing codeine in drug, human plasma, and urine samples.