Free Access
Volume 27, Number 1, January/February 1999
Importance de la lipophilie en modélisation moléculaire
Page(s) 53 - 56
Section Original articles
Analusis 27, 53-56 (1999)
DOI: 10.1051/analusis:1999105

Potentiometric enantioselective membrane electrode for s-enalapril assay

H.Y. Aboul-Enein1, R. I. Stefan2 and J.F. van Staden2

1  Bioanalytical and Drug Development Laboratory, Biological and Medical Research Department (MBC-03), King Faisal Specialist Hospital and Research Centre, P.O. Box 3354, Riyadh 11211, Saudi Arabia
2  Department of Chemistry, University of Pretoria, Pretoria 0002, South Africa

A novel potentiometric, enantioselective membrane electrode based on graphite paste (graphite powder and paraffin oil), impregnated with 10-3 mol/L 2-hydroxy-3-trimethylammoniopropyl-$\beta$-cyclodextrin (as chloride salt) solution, has been constructed. The potentiometric, enantioselective membrane electrode can be used for the reliable assay of S-enalapril as raw material and from its pharmaceutical formulations in the concentration range of $3.6 \times 10^{-5}{-}6.4 \times 10^{-2}$ mol/L with a detection limit of $1.0\times 10^{-5}$ mol/L and with an average recovery of 99.96% (RSD = 0.098%), using a chronopotentiometric (zero current) technique. The enantioselectivity was determined versus D-proline and it was shown only L-proline is the main interfering compound. The surface of the electrode can be regenerated by simply polishing to obtain a fresh surface which is ready to be used in a new assay.

Key words: Potentiometry / enantioselective membrane electrode / enantioselective analysis / 2-hydroxy-3-trimethylammoniopropyl-$\beta$-cyclodextrin / S-enalapril.

© EDP Sciences, Wiley-VCH 1999