Thiamine determination from medicines using gas chromathography

Lucian Copolovici1, Simona Bungǎu2 and Felicia Drǎgan2

1Tartu University, Institute of Molecular and Cell Biology, 23 Riia St., Estonia, e-mail: clucian@chem.ubbcluj.ro
2Oradea University, Faculty of Medicine and Pharmacy, 23 N. Jiga St., Oradea, Romania

Thiamine (vitamin B1), a water-soluble vitamin, is a natural nutrient present in many foods and is also added as an essential nutrient. It has been used for the prevention and treatment of beriberi, neuralgia, etc. in medical doses or vitamin B1-enriched food or drinks. The recommended USP (United States Pharmacopeia) methods for the determination of water soluble vitamins are tedious and time-consuming, and currently automated methods, although fast and reliable, can assay only a single vitamin in each run. Thus, the development of a rapid and reliable method for the simultaneous liquid chromatographic assay of these vitamins is necessary [1]. UV-Vis spectrophotometry [2], chemiluminiscence [3], capillary electrophoresis [4], microbiology [5], kinetic methods [6] and high-performance liquid chromatography [7] have been also proposed for the determination of vitamins. In this study, a simple and rapid chromatographic method for the determination of thiamine is proposed. The samples were injected directly into the chromatographic system without previous treatment or dilution. 
Calibration lines have been obtained under appropriate conditions. Statistic equation for the curve is:
[thiamine]		with r=0.9998; s0=4; N=11.
Detection limit was established at 0.06 g/L and determination limit was 0.2 g/L. The effect of some organic compounds and heavy metals associated with drugs was studied. Most cations and organic substance did not interfere even when present in 200-fold excess relative to B1 vitamin. Vitamins B6, B2, B12 do not interfere in determination at 100-fold excess relative to thiamine. 
The method was applied for the solid sample of pharmaceutical preparation and for injections. An acceptable correlation is found between certified content given by producers and the results obtained by the proposed method.

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