Design of a Vitamin B1-Selective Electrode Based on an Ion-Pair and Its Application to Pharmaceutical Analysis

Vitamin B-1-selective electrodes with PVC membrane were developed that contain ion associates of vitamin B-1 with an inorganic anion, BiI4-, and an organic anion, brilliant yellow, as electrode-active substances. The linearity ranges of the electrode function are 1.0 x 10(-5)-1.0 x10(-2) and 1.0 x 10(-4)-1.0 x10(-2) M, the electrode function slopes are 33.0 +/- 1.0 and 33.1 +/- 1.1 mV decade(-1), the detection limits are 5.5x10(-6) and 8.3 x 10(-5) M for BiI4- and brilliant yellow respectively. The working range of pH is 5-12. The efficiency of the use of electrodes for the vitamin B-1 content control in multivitamin pharmaceutical preparations was shown by direct potentiometry and potentiometric titration methods.