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

Vitamin B1‐selective electrodes with PVC membrane were developed that contain ion associates of vitamin B1 with an inorganic anion, BiI4−, and an organic anion, brilliant yellow, as electrode‐active substances. The linearity ranges of the electrode function are 1.0×10−5–1.0×10−2 and 1.0×10−4–1.0×10−2 M, the electrode function slopes are 33.0±1.0 and 33.1±1.1 mV decade−1, the detection limits are 5.5×10−6 and 8.3×10−5 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 B1 content control in multivitamin pharmaceutical preparations was shown by direct potentiometry and potentiometric titration methods.