Quinine, Quinidine and Their Tert-butyl Carbomylated Derivatives as Chiral Selectors in the Enantioselective, Potentiometric Membrane Electrodes Design: Their Application for the Assay of (S) and (R) Enantiomers of 3,5-dinitrobenzoyl Leucine

Abstract

Quinine, quinidine, tert-butyl carbomylated quinine and tert-butyl carbomylated quinidine are proposed as new chiral selectors in the construction of enantioselective, potentiometric membrane electrodes (EPMEs). A matrix based on carbon paste is used for the design of the electrodes. Electrodes revealed near-Nernstian values for the concentration range of the analytes ((S) and (R)-dinitrobenzoyl leucine (DNB-Leu)) situated in low magnitude order, with low limits of detection (lower than 10−7 mol/L). Quinine and quinide based EPMEs proved to be enantioselective for the (S)-DNB-Leu, while the tert-butyl carbomylated quinine based EPME was enantioselective for (R)-DNB-Leu. The tert-butyl carbamoyl quinidine based electrode was enantioselective only for specific ratios between the (S) and (R)- DNB-Leu enantiomers.