Rapid determination of gallamine triethiodide (Flaxedil®) and pancuronium bromide (Pavulon®) in pharmaceutical and urine matrices by means of modified-carbon-paste ion-selective electrodes

A new analytical method for the determination of gallamine triethiodide (Flaxedil®; 1) and pancuronium bromide (Pavulon®; 2), two muscle relaxants used in surgical operations and in pain relief, has been developed. Our approach relies on rapid, precise, and sensitive potentiometric sensors based on modified-carbon-paste ion-selective electrodes (CP-ISEs). Linear calibration graphs in the working ranges of ca. 4.5-892 and 7.3-733 μg/ ml (in H₂O, pH 7.0, T = 25°) were established for 1 and 2, respectively; and Nernst slopes corresponding to three- or two-electrons transfers, respectively, were obtained. The method works best in a pH range of 7-9. Average relative errors of 2.12 and 2.14%, with average standard deviations of 1.98-2.47 and 2.64-3.45, respectively, were obtained for urine samples of 1 and 2. The corresponding relative errors for the pharmaceutical samples were 1.59 and 1.64%, with standard deviations of 0.54 -1.34 and 0.52 -1.67, respectively. Statistical Student and F tests were applied to the data, and satisfactory results were obtained.