Kinetic Potentiometric Determination of Penicillamine and N-Acetyl-L-Cysteine Based on Reaction with Iodate

Optimization and application of simple kinetic potentiometric method for the determination of D-penicillamine (PEN) and N-acetyl-L-cysteine (NAC) in pharmaceutical is described. The method was based on the reaction between thiol and iodate, in the presence of small quantity of iodide. The changes of potentials, AE, in fixed time interval were measured with an iodide ion selective electrode versus a double-junction reference electrode. Good linearity between AE and negative logarithm of analyte concentration is achieved in the range of the studied drugs concentration from 1.0 × 10–6 to 1.0 × 10–4 M. The limit of detection for PEN is 9.0 × 10–8 M and for NAC is 1.0 × 10–7 M. The applicability of the proposed method to the determination these thiols in pharmaceutical preparation was demonstrated by investigating the effect of potential interferences and by analysis of commercial preparations.