A STUDY OF THE DIFFERENTIAL-PULSE POLAROGRAPHIC AND STRIPPING VOLTAMETRIC BEHAVIOR OF THE H+ K+ ATPASE INHIBITOR SK-AND-F-95601 AND ITS DEGRADATION PRODUCTS/

The differential pulse polarographic (DPP) behavior of SK&F 95601 (I) has been studied in the pH range 0 to 14. At pH less than or equal to 2, (I) rapidly degrades into the sulfenamide (D-1(I)) and sulfide (D-2 (I)), which are both reduced by 2e(-) processes, the former being subj ect to strong reactant adsorption. SK&F 95601 itself is reduced in a 4 e process up to pH10, and either pK(2) or pK(3) values, determined spe ctrophotometrically, are manifested polarographically at neutral pH. A pK(5) value of 9.0 corresponding to the benzimidazole N-H group depro tonation is manifested polarographically with a pK'(5) value of ca. 11 . SK&F 95601 and its degradation products D-1(I), degraded D-1(I), and D-2(I) can all be determined by adsorptive stripping voltammetry (AdS V) with limit of detections (LODs) of 10(-8) mol dm(-3), except for th e latter molecule with an LOD of 10(-7) mol dm(-3). These LODs are sup erior to those determined by DPP. Mixtures of these molecules can also be resolved with similar LODs. Cd2+ can be determined by ASV with a s uperior LOD in the presence of (I), i.e., 0.08 ppb as compared to 0.57 ppb in its absence, due to chelation phenomena.