Maltodextrins as new chiral selectors in the design of potentiometric, enantioselective membrane electrodes

Maltodextrins (dextrose equivalent (DE) 4.0-7.0, 13.0-17.0, and 16.5-19.5) are proposed as novel chiral selectors for the construction of potentiometr ic, enantioselective membrane electrodes. The potentiometric, enantioselect ive membrane electrodes can be used reliably for the assay of S-captopril a s raw material and in pharmaceutical formulations such as Novocaptopril tab lets, by use of direct potentiometry. The best response was obtained when m altodextrin with higher DE was used for construction of the electrode. The best enantioselectivity and time-stability was achieved for the lower DE ma ltodextrin. L-proline was found to be the main interferent for all the prop osed electrodes. The surface of the electrodes can be regenerated by simply polishing; this furnishes a fresh surface ready for use in a new assay.