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A study of the differential pulse polarographic and stripping voltammetric behavior of the H + /K + ATPase inhibitor SK&F 95601 and its degradation products
Author(s) -
McClean S.,
Maxwell T.,
Ramachandran V. N.,
O'Kane E.,
Smyth W. F.
Publication year - 1994
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.1140061113
Subject(s) - polarography , chemistry , deprotonation , stripping (fiber) , detection limit , adsorptive stripping voltammetry , analytical chemistry (journal) , chelation , molecule , nuclear chemistry , inorganic chemistry , chromatography , voltammetry , electrochemistry , ion , electrode , organic chemistry , electrical engineering , engineering
The differential pulse polarographic (DPP) behavior of SK&F 95601 (I) has been studied I the pH range 0 to 14. At pH ≤ 2, (I) rapidly degrades into the sulfenamide (D 1 I ) and (D 2 I ), which are both reduced by 2e − processes, the former being subject to strong reactant adsorption. SK&F 95601 itself is reduced in a 4e process up to pH10, and either pK 2 or pK 3 values, determined spectrophotometrically, are manifested polarographically at neutral pH. A pK 5 value of 9.0 corresponding to the benzimidazole N‐H group deprotonation is manifested polarographically with a pK′ 5 value of ca. 11. SK&F 95601 and its degradation produce D 1 I , degraded D 1 I , and D 2 Ican all be determined by adsorptive stripping voltammetry (AdSV) with limit of detections (LODs) of 10 −8 mol dm −3 , except for the latter molecule with an LOD of 10 −7 mol dm −3 . These LODs are superior to those determined by DPP. Mixtures of these molecules can also be resotved with similar LODs. Cd 2+ can be determined by ASV with a superior LOD in the presence of (I), i.e 0.08 ppb as compared to 0.57 ppb in its absence, due to chelation phenomena.