Vitamin assay

Assoc. Vitamin Chemists, Methods of Vitamin Assay," New York, Interscience Publishers,... 

Coupled LC-LC can separate high-boiling petroleum residues into groups of saturates, olefins, aromatics and polar compounds. However, the lack of a suitable mass-sensitive, universal detector in LC makes quantitation difficult SFC-SFC is more suitable for this purpose. Applications of multidimensional HPLC in food analysis are dominated by off-line techniques. MDHPLC has been exploited in trace component analysis (e.g. vitamin assays), in which an adequate separation for quantitation cannot be achieved on a single column [972]. LC-LC-GC-FID was used for the selective isolation of some key components among the irradiation-induced olefinic degradation products in food, e.g. dienes and trienes [946],... 

A10. Association of Vitamin Chemists, Inc., in Methods of Vitamin Assay, pp. 69-97. Interscience, New York, 1947. 

D6. Diderig, N. A., Biochemical mutants of microorganisms in vitamin assay. Svensk Farm. Tidskr. 59, 1-7 (1955). 

Considering the importance of vitamins in human health and the legislation regarding them, the analysis of these compounds appears to be very important. Indeed, vitamin assays in food... 

G. F. M. Ball, Water-Soluble Vitamin Assay in Human Nutrition, Chapman Hall, Cornwell, U.K., 1994. 

Bill . G.F.M Fat Soluble Vitamin Assays in Foot I Anolssis . 4 Comprehensive Reriesr. Elsevier. New York. NY. 1989. 

One of the more important areas of use of ultraviolet instruments is the identification and determination of biologically active substances. Many components in body fluids can be determined either directly or through colorimetric methods. Drugs and narcotics can be measured both in the body as well as in formulations. Vitamin assay is another related activity. Nearly all metals and nonmetals can be determined through their ultraviolet absorption or by colorimetric methods. In recent years, ultraviolet instruments have been used extensively for the determination of air and water pollutants, such as aldehydes, phenolics, and ozone ... 

Cleanup or fractionation procedures that have been used in the more recent fat-soluble vitamin assays include sterol precipitation, open-column chromatography, solid-phase extraction, and high-pressure gel permeation chromatography. High-performance LC has been used on a semipreparative scale in vitamin D and vitamin K assays to obtain purified fractions of sample extracts. This technique is discussed in Sec. V.B.3. 

The more recent applications of open-column chromatography in fat-soluble vitamin assays utilize liquid-solid (adsorption) chromatography using gravity-flow glass columns dry-packed with magnesia, alumina, or silica gel. Such columns enable separations directly comparable with those obtained by thin-layer chromatography to be carried out rapidly on a preparative scale. 

The majority of published HPLC techniques used in fat-soluble vitamin assays have utilized 5- or 10-/zm particles of porous silica or derivatized silica packed into stainless steel tubes of typical length of 250 mm and standard internal diameter (ID) of 4.6 mm. Radially compressed... 

GFM Ball. Fat-Soluble Vitamin Assays in Food Analysis. London Elsevier Applied Science, 1988, pp 116-141. 

ER Elkins, JA Dudek. Sampling for vitamin analyses. In J Augustin, BP Klein, D Becker, PB Venu-gopal, eds. Methods of Vitamin Assay. 4th ed. New York Wiley, 1985, pp 135-151. 

Association of Vitamin Chemists. Vitamin E (tocopherols). Methods of Vitamin Assay. 3rd ed. New York Interscience, 1966, pp 363-402. 

GFM Ball. Water-Soluble Vitamin Assays in Human Nutrition. London Chapman Hall, 1994, pp 142-386. 

R. Strohecker and H. M. Henning, Vitamin Assay, Tested Methods, Verlag Chemie, Weinheim, 1966. 

Ball GFM. Pantothenic acid. Water-soluble vitamin assays in human nutrition. New York Chapman and Hall, 1994. 

Immobilized Lactobacillus arabinosus strain ATCC 8014 was used for analysis of nicotinic acid (31). The vitamin assay was performed with a pH-electrode and bacteria immobilized in agar. 

There are a number of chemical and physical requirements for bacterial growth, such as carbon and nitrogen sources, pH, and temperature (see Chapter 1). Some antibiotic assay organisms, such as Bacillus subtilis and Escherichia coli, grow on simple media, others, such as the lactobacilli used for vitamin assay, need an enriched medium containing a wide range of nutritional supplements. Many media are commercially available in the dehydrated form from various suppliers. 

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