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/
S. Mcclean et al., 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/, Electroanalysis, 6(11-12), 1994, pp. 996-1003
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.