Voltammetric determination of alpha lipoic acid using chitosan-based polyurethane membrane electrode

In this study, chitosan-based polyurethane (PU) membrane modified electrodes were prepared for sensitive, practical and fast measurement of alpha-lipoic acid (ALA), which is an important biomolecule. PU membranes were synthesized using hexamethylene diisocyanate, chitosan, caffeic acid and polyethylene glycol compounds. Chemical structure, thermal stability and morphological properties of the prepared PU membranes were determined with different instrumental techniques. Surface morphology, wettability and hydrophilicity of synthesized chitosan-based PU membranes were investigated. Gold electrode was modified by these PU membranes with different film thicknesses. The bare and PU membrane coated electrodes were used for deduction of ALA by cyclic voltammetry, differential pulse voltammetry and amperometry techniques. In addition, sensitivity, linearity, repeatability and deduction limit of PU modified electrodes were investigated. Modified electrodes showed wide linear detection range (5-200 mu molL(-1)), low detection limit (4.931 mu molL(-1)) and short response time. Results show that polyurethane modified electrodes are good alternative for ALA determination.