Determination of iodinated X-ray contrast agents in pharmaceutical formulations and artificial urine samples by differential pulse voltammetry
A new differential pulse voltammetry (DPV) technique was developed and validated for the determination of iopromide (IOP), iodixanol (ION) and amidotrizoic acid (DTZA), which belong to the iodinated X-ray contrast agent group in pharmaceutical formulations and artificial urine samples. All measurements were performed in the three-electrode configuration with a glassy carbon electrode (GCE) as a working electrode, Ag|AgCl|KCl(sat.) as a reference and platinum wire as an auxiliary electrode. The supporting electrolytes for determination of selected contrast agents were mixtures of methanol and Britton–Robinson buffers with different pH values. Quantification was performed by means of calibration curve and standard addition methods. The calibration curves for ION, IOP and DTZA were linear over a concentration range of 0.032–0.258, 0.039–0.394 and 0.041–0.326 mM, respectively. Good linear behaviour over the investigated concentration ranges was observed with values of r2 higher than 0.994 for all the iodinated contrast agents (ICA). The limits of detection (LOD) and limits of quantification (LOQ) for all analysed contrast agents were calculated and recovery studies were also performed. The percentage recoveries varied from 94.44 to 101.05% (after SPE procedure). Analytical methods for the preparation of urine samples were worked out and optimized before its voltammetry measurements (solid phase extraction – SPE). The differential pulse voltammetry method described in this work is the first procedure allowing determination of three iodinated X-ray contrast agents (IOP, ION and DTZA) in pharmaceutical formulations and artificial urine samples.