Ion-selective membrane electrodes for the determination of the muscle relaxants pancuronium,tubocurarine, gallamine and succinylcholine

Ion-selective PVC membrane electrodes for the peripherial muscle relaxants pancuronium (PAN), tubocurarine (TUB), gallamine (GAL) and succinylcholine (SUC) are presented. The preparation of the electrode membranes contaimng ion pairs of the muscle relaxants with two different anionic counter ions, dipicrylaminate (DPA) and tetraphenylborate (TPB), are reported. The detection limits for all electrodes were ca. 10^?6 mol 1^?1 at physiological pH values and the measured slopes were dose to the values theoretically expected. Changes in the detection limits and the slopes of the electrodes in the pH range 2.5–11.0 were found to be due to reversible changes in the protonation state of the amine groups of the muscle relaxant (TUB) or the counter ion (DPA). The PAN-TPB and PAN-DPA ion-pair complexes were observed to have a bettet stability than those formed with TUB, GAL and SUC. The observed selectivity coefficients of the PAN-TPB electrodes were 10^?0.3 towards TUB and 10^?1.8 towards GAL.