Thiamine assay

Medium for Thiamine Assay with Ochromonas malhamensisa... 

Fig. 1. Typical growth curve in thiamine assay with Ochromonas malhamensis [Baker et al. (B15)].

Pre-column derivatization is normally used although post-column derivati-zation should be more convenient for routine analyses, it is not often applied. In this case, the separation of thiamine requires the use of ion-pair liquid chromatography since it is not retained on a reverse-phase column (Blake 2007). This technique also increases the sensitivity and reproducibility of the thiamine assay. 

Thiochrome. Tricyclic alcohol (C12H14 N4OS) formed by oxidation of thiamine and giving a blue fluorescence under ultraviolet light that serves as the basis of a method for thiamine assay. 

Thiamine has also been measured by bioassay, a marine yeast being used as the assay organism [474,475]. Marine bacteria [476,477], marine yeasts [475], and dinoflagellates [478] have been used for the assay of biotin. 

The recognition of their structure permits the determination of vitamins by the tools of analytical chemistry, but while such methods are widely used in industrial production, the minute quantities in body fluids and tissues limit the purely chemical approach to a few members of this group present in relatively high concentration, e.g., vitamin C (K5). Microchemical methods are in use for the determination of thiamine, riboflavin, and some of the fat-soluble vitamins, based on the most sensitive colorimetric and, in particular, fluorometric techniques. Vitamin D, on the other hand, is determined by animal assay. 

The inoculum for the assay is prepared by growing Ochromonas for 4-6 days in the basal medium supplemented with 10 m ig/ml of thiamine. The culture is then diluted 1 100 with basal medium a drop of this dilution serves as an inoculum for each assay flask. There is no... 

The clinical significance of thiamine and its necessity for pyruvic acid oxidation has been discussed. Recent reports concerning the coenzyme function of thiamine in pentose (H13), tryptophan (D2), and lipoic acid metabolism (R6) have increased our knowledge of thiamine in metabolism and lend added interest to the role of thiamine in clinical problems. This method has also been used to assay thiamine in liver and brain. 

B20. Banhidi, Z. G., Some aspects of the nutrition of Lactobacillus fermenti 36 on the tube assay of thiamine. Acta Chem. Scand. 12, 517-527 (1958). 

Strong acid/strong base titrations are used in pharmacopoeial assays of perchloric acid, hydrochloric acid, sulphuric acid and thiamine hydrochloride. 

Argentimetric titration is used in pharmacopoeial assays of sodium chloride and potassium chloride tablets, thiamine hydrochloride, mustine chloride and carbromal. 

The determination of vitamins in pharmaceutical preparations continues to receive considerable attention. The voltammetric oxidation of vitamin A at a carbon paste electrode in the presence of vitamin E, a potential source of error in the assay, has been described [142,143]. Other assays involve the polaro-graphic determination of niacinamide [144-146], menadione (vitamin K3) [147], riboflavin (vitamin B2) [148], thiamine, riboflavin, and nicotinamide in multivitamin preparations [149], and multivitamins [150]. 

Kawasaki (68) briefly reviewed HPLC methods for determining total thiamine alone and in combination with riboflavin. Russell (44) provided a more detailed summary of HPLC methods, published between 1990 and 1994, for thiamine alone and in conjunction with other vitamins. Ball (45) reviewed selected HPLC analyses for thiamine in various foods, as well as other chemical and microbiological assays. 

Assay Determine as directed in the monograph for Thiamine Hydrochloride. Calculate the quantity, in milligrams, of C12H17N504S in the sample taken by the formula... 

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