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.