A Solid State Polymer‐Coated Electrode Containing a Chiral Crown Ether Derivative for Enantioselective Detection of Phenylglycine Methyl Ester Isomer

All solid‐state enantioselective electrode (ASESE) based on a newly synthesized chiral crown ether derivative ((R)‐(?)‐(3,3′‐diphenyl‐1,1′‐binaphthyl)‐23‐crown‐6 incorporating 1,4‐dimethoxybenzene) was prepared and characterized by potentiometry. The ASESE clearly showed enantiomer discrimination for methyl esters of alanine, leucine, valine, phenylalanine, and phenylglycine, where the enantioselectivity for phenylglycine methyl ester was the highest (K_R,S=8.5±7.1%). Experimental parameters of ASESE for the analysis of (R)‐(?)‐phenylglycine methyl ester were optimized. The optimized ASESE showed a slope of 55.3±0.2 mV/dec for (R)‐(?)‐phenylglycine methyl ester in the concentration range of 1.0×10^?5–1.0×10^?2 M and the detection limit was 9.0×10^?6 M. The ASESE showed good selectivity for (R)‐(?)‐phenylglycine methyl ester against inorganic cations and various amino acid methyl esters. The concentration of (R)‐(?)‐phenylglycine methyl ester was determined in the mixture of (R)‐(?) and (S)‐(+)‐phenylglycine methyl ester, which ratios varied from 2 : 1 to 1 : 9. The lifespan of the electrode was alleged to be 30 days.