Potentiometric membrane sensors for the selective determination of pyridoxine hydrochloride (vitamin B6) in some pharmaceutical formulations.

The construction and general performance characteristics of two novel potentiometric PVC membrane sensors responsive to the pyridoxine hydrochloride known as vitamin B6 (VB6) are described. These sensors are based on the use of the ion-association complexes of the pyridoxine cation with phosphomolybdate, and phosphotungstate counter anions as ion pair in a plasticized PVC matrix. The electrodes show a stable, near-Nernstian response for 6x10(-5)-1x10(-2) M VB6 at 25 degrees C over the pH range 2-4 with a cationic slope of 54.