Enantioselective potentiometric membrane electrodes based on alpha-, beta- and gamma-cyclodextrins as chiral selectors for the assay of L-proline.

Novel enantioselective, potentiometric membrane electrodes based on carbon paste impregnated with alpha-, beta- and gamma-cyclodextrins are reported. Response characteristics showed that the proposed electrodes could be reliably used in the assay of l-proline (l-pro), with the best enantioselectivity and time-stability exhibited by alpha-cyclodextrin. The enantioselective, potentiometric membrane electrodes based on the proposed unsubstituted cyclodextrins (CDs) showed lower detection limits (in the region of 10(-10) to 10(-9)mol L(-1)) than the one previously studied, based on beta-cyclodextrin derivative [R.I. Stefan, J.F. van Staden, H.Y. Aboul-Enein, Anal. Lett. 31 (1998) 1787-1794]. The surfaces of the electrodes are easily renewable by simply polishing on an alumina paper.