Electrochemical determination of L-lactate using phenylboronic acid monolayer-modified electrodes

The surface of a gold (Au) disk electrode was modified with a self-assembled monomolecular layer of dithiobis(4-butylamino-m-phenylboronic acid) (DTBA-PBA) to prepare L-lactate-sensitive electrodes. The DTBA-PBA-modified electrodes exhibited an attenuated cyclic voltammogram (CV) for the Fe(CN)₆^3- ion in the presence of L-lactate, as a result of the formation of phenylboronate ester of L-lactate accompanied with the addition of OH^- ion to the boron atom. In other words, the negatively charged DTBA-PBA monolayer blocked the electrode surface from the access of the Fe(CN)₆^3-/4- ions. Thus, the DTBA-PBA monolayer-modified Au electrode can be used for determining l-lactate on the basis of the change in redox current of Fe(CN)₆^3-/4- ions. The calibration graph useful for determining 1 - 30 mM L-lactate was obtained.