Thiamine-reineckate liquid membrane electrode for the selective determination of thiamine (vitamin B1) in pharmaceutical preparations

Abstract

The construction and electrochemical response characteristics of a liquid membrane electrode for thiamine (vitamin B1) based on the formation of an ion pair between the thiamine cation and the reineckate anion in nitrobenzene are described. The electrode showed a linear response for thiamine over the concentration range 10–3–10–6–M with a cationic slope of 31.6–mV per concentration decade and had a wide working pH range (4–8), fast response time (1–2–min), low detection limit (0.3–µg–ml–1) good stability and reasonable selectivity. The direct potentiometric determination of vitamin B1 in some pharmaceutical preparations using the proposed electrode gave an average recovery of 98.1% of the nominal values and a mean standard deviation of 1.3%, which compare fairly well with data obtained using the British and United States pharmacopoeial methods.