Vitamin B_1-Sensitive Poly(vinyl chloride) Membrane Electrode Based on Hydrophobic Tetraphenylborate Cation Exchangers

There have been many papers on liquid membrane and solvent polymeric membrane electrodes sensitive to drug substances."2 Most of these electrodes are based on liquid ion-exchangers. One of the disadvantages of these types of electrodes is their short lifetime. This is due to dissolution of the ion exchanger in the membrane into a sample solution, which leads to a decrease in sensitivity of the electrode.3'4 To maintain the sensitivity of the electrode by using more hydrophobic ion exchangers was thought to be one way to solve problem. Recently, two (T.S. and H.K.) of the authors prepared tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (TFPB), which shows high acid-resistivity and has high hydrophobicity.5 TFPB is expected to be an excellent cation exchanger for many kinds of liquid cation exchange membrane electrodes having high sensitivity. In this paper, we briefly report on a highly sensitive new vitamin B1 electrode, which uses TFPB and its analogue with more hydrophobic substituent groups. Experimental