Ri. Stefan et al., A new construction for a potentiometric, enantioselective membrane electrode - its utilization to the S-captopril assay, TALANTA, 48(5), 1999, pp. 1139-1143
A novel potentiometric, enantioselective membrane electrode based on graphi
te paste (graphite powder and paraffin oil) has been constructed. The graph
ite paste is impregnated with 2-hydroxy-3-trimethylammoniopropyl-beta-cyclo
dextrin (as chloride salt) solution, 10(-3) mol l(-1). The potentiometric,
enantioselective membrane electrode can be used reliable for S-captopril as
say as raw material and from Novocaptopril tablets, using a chronopotentiom
etry (zero current) technique, in the 10(-6)-10(-2) mol l(-1) concentration
range (detection limit 2 x 10(-7) mol l(-1)), with an average recovery of
99.99% (RSD = 0.05%). The enantioselectivity was determined over R-captopri
l and D-proline. The response characteristics of the enantioselective, pote
ntiometric membrane electrode were determined also for R-captopril. It was
shown that only L-proline is the main interfering compound. The surface of
the electrode can be regenerated by simply polishing, obtaining fresh surfa
ce ready to be used in a new assay. (C) 1999 Elsevier Science B.V. All righ
ts reserved.