Vitamin determination

Gel permeation ehromatography (GPC)/normal-phase HPLC was used by Brown-Thomas et al. (35) to determine fat-soluble vitamins in standard referenee material (SRM) samples of a fortified eoeonut oil (SRM 1563) and a eod liver oil (SRM 1588). The on-line GPC/normal-phase proeedure eliminated the long and laborious extraetion proeedure of isolating vitamins from the oil matrix. In faet, the GPC step permits the elimination of the lipid materials prior to the HPLC analysis. The HPLC eolumns used for the vitamin determinations were a 10 p.m polystyrene/divinylbenzene gel eolumn and a semipreparative aminoeyano eolumn, with hexane, methylene ehloride and methyl tert-butyl ether being employed as solvent. 

The researcher in food and its analysis is keenly aware that his task will not be finished until the quality of a food product can be defined completely in precise terms of its flavor, color, texture, and nutritive value. The goal is distant but the journey is well begun. The papers contained herein describe the present state of affairs in each of as many of the fields of food analysis as time for the symposium permitted. Each has been covered by an outstanding worker in his field. It is unfortunate that B. L. Oser s excellent paper on Advances in Vitamin Determination does not appear. His more comprehensive review of food analysis which appeared in Analytical Chemistry [21, 216 (1949)] should by all means be studied along with the papers contained herein. 

The requirements of dairy cattle for B-vitamins, determined almost half a century ago, concluded that a ruminant animal does not require an exogenous supply of B-vitamins because its rumen microflora should synthesise enough of these compounds to avoid deficiency. Since then, dairy cows have greatly increased their average milk and milk component yields. More recent studies have shown that B-vitamin supply in dairy cows is increased by supplementation, although losses in the rumen are extensive (Santschi et al., 2005). Whilst there are few reports of B-vitamin supplementation affecting milk quality, supplemental biotin has been shown to directly improve milk yield (Majee et al., 2003). 

Analysis of vitamin content of food materials appears to be a developing field. B vitamins in rice were analyzed using a mobile phase which contained pentanesulfonic acid and heptanesulfonic acid (558). Although the peaks were not sharp, the separation of the vitamins was satisfactory. Vitamin D in fortified milk has b n analyzed after removal Of cholesterol and carotenes in a preliminary cleanup (559, 540). Vitamin A has been analyzed in margarine, infant formula, and fortified milk (541, 542). Reports of the analysis of other vitamins in food are few to te but this mode of analysis can be expected to rapidly expand in the future in light of the variety of vitamin determinations in formulations which have been done (see Section VIII,F,l). 

According to the vitamin determination by Hemandez-Carmona et ah (2009), there are significant differences of certain vitamins content caused by seasonal variations, for example, in Eisenia arborea. It was observed that the highest content of some vitamins (A, Bi, B2, and partly also vitamin C) was in spring opposite to the lowest spring value of vitamin E. Moreover, season was observed as the factor of carotenes content affection also in Palmaria. The highest content of carotenes was foimd in summer and the lowest in winter (L0vstad Holdt and Kraan, 2010). 

The delay in the acquisition of systematic data on the tissue concentrations of vitamins in relation to age is probably to a great extent due to the lack of suitable procedures for the analysis of several of these compounds. When proper techniques for vitamin determinations have been developed, it would be desirable to obtain such information from analyses of both human and animal tissues. 

Research into new analytical techniques for foodstuffs continues, striving for greater accuracy, sensitivity or simplicity, for more rapid methods, for simultaneous multielement analysis, etc. Chromatographic techniques, e.g., LC, GLC, GC-MS, have led to great improvements in the levels of accuracy, sensitivity, and detection that can be achieved for many analytes including carbohydrates, certain vitamins, chemical residues, and additives. Work is still required, for instance, in the area of vitamin analysis in order to provide standard techniques that are applicable to all food types and that would enable concurrent multi-vitamin analysis to take place. Many of the microbiological assays currently used for vitamin determination involve long incubation times and more rapid techniques are needed. 

Methods employed largely vary from sample material to sample material, and for determination of most vitamins many different analytical methodologies can be used. Care must be taken in choosing the best method. Different methods can yield different results, e.g., due to different sample preparation or different specificity of the method toward the analyte. For example, the result of microbiological vitamin determinations is usually a biological activity expressed as an amount of pure vitamin showing the same effect in the test. This assumption is often correct, but the possible presence and influence of, e.g., vitamers or metabolites with vitamin... 

Different samples or matrices require suitable adaptation to the quantification system, such as fat-soluble vitamin determination in serum, human nutritional supplements,and infant formulas, using... 

The next generation of HPLC detectors, namely mass spectrometers, are now available and being deployed for water-soluble vitamin determinations in dietary supplements with electrospray ionization interface (ESI) (Holler et al. 2006). There remain obstacles to overcome for multivitamin analyses in complex food matrices, as co-elution of vitamins or excipients can compromise... 

In food analysis using ME-ED technology, CNTs modification has been studied using both GCE and CSPEs for vitamin detection [51]. CSPE-CNTs modified have become the best approach since their improvement of sensitivity and lowered LCDs with the advantages of easy surface modification, inherent miniaturization, and disposability. The performance of these CNT detectors for vitamins determination integrating calibration has also been evaluated with an excellent results. Vitamins calibration and analysis were carried out in less than 400 s with recoveries higher than 95%. 

Crevillen, A.G., Blasco, A.J., Gonzalez, M.C., and Escarpa, A. (2006) Fast and reliable route integrating calibration and analysis protocols for water-soluble vitamins determination on board microchip-electrochemistry platforms. Electrophoresis, 27, 5110-5118. 

Due to the complicated composition of food, it is clear that reliable vitamin determinations require high chromatographic efficiency and detection sensitivity, as well as excellent detection specificity. Huorescence detection fulfills these requirements. This mode of detection is therefore virtually exclusively used in modern chromatographic vitamin Be analysis of food. Several methods suitable for food analysis, summarized in Table 4, have been described in the iiterature. 

Vitamins determined Chromatographic conditions Detection Foods analyzed Reference... 

Turner C, Persson M, Mathiasson L, Adlercreutz P, King JW. Lipase-catalyzed reactions in organic and supercritical solvents application to fat-soluble vitamin determination in milk powder and infant formula. Enzyme Microb Tech 2001 29(2-3) 111-21. 

Hie problem has been approached mainly by adding labeled organic compounds to growing cultures of the riboflavin-producing organism. The riboflavin was then isolated from the fermentation broth, and the position of label in the vitamin determined. The methods employed for the chemical degradation of riboflavin are summarized in Fig. 1. 

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