Total vitamin

As described ia the USP, phytoaadioae is a mixture of the cis- and trans-isomers of vitamin IQ. This mixture should not contain mote than 103% and not less than 97.0% of total vitamin K content. The amount of the cis-isomer is also specified and is not to exceed 21%. In addition to the pure substance, the USP also describes methods for the analysis of parental as well as tableted forms of the vitamin (21). 

Six compounds have vitamin Bg activity (Figure 45-12) pyridoxine, pyridoxal, pyridoxamine, and their b -phosphates. The active coenzyme is pyridoxal 5 -phos-phate. Approximately 80% of the body s total vitamin Bg is present as pyridoxal phosphate in muscle, mostly associated with glycogen phosphorylase. This is not available in Bg deficiency but is released in starvation, when glycogen reserves become depleted, and is then available, especially in liver and kidney, to meet increased requirement for gluconeogenesis from amino acids. 

Carotene content is a critical factor for several fruits and vegetables such as carrots, because consumers consider this vegetable as a major single source of provitamin A, providing 17% of the total vitamin A consumption (Barry-Ryan and O Beirne 2000). Recently, the demand for carotenoids, especially (3-carotene, has increased because of its health benefits (Ruiz-Cruz and others 2007). 

Blood of normal subjects was obtained from an antecubital vein, diluted 1 5 with pH 4.5 buffer,2 and autoclaved 30 minutes to convert bound cobalamin into its microbiologically active form serum was treated like blood. This procedure allowed estimation of total vitamin Bi2. For the subsequent inoculation of specimens (a) E. coli as a loopful from nutrient agar suspended in 25 ml of medium, (b) L. leichmannii, an 18-hour culture diluted 1 10 in basal medium, (c) E. gracilis, strain Z, and (d) O. malhamensis are inoculated directly from a 5-day culture grown in liquid maintenance medium. One drop into a culture flask served as inoculum. The bacteria required 18-hours for full growth protozoa, 4-5 days. 

Homogenization in NaOAc buffer and Na cyanide addition of enzyme amylase and pepsin (for total vitamin) incubation at 32°C for 30 min (or 37°C for 3h) immuno-affinity column... 

Near-total vitamin A depletion of the eye does not significantly decrease photic signalling to the SCN, as measured by photic immediate-early gene induction... 

The vitamin D activity in animal products is contributed by both vitamin D3 and 25-hy-droxyvitamin D3. Typical values of the hydroxylated metabolite (/zg/100 g) are bovine muscle, 0.2-0.3 bovine liver, 0.3-0.5 bovine kidney, 0.5-1.0 (36) and egg yolk, 1.0 (37). 25-Hydrox-yvitamin D3 is of nutritional significance it is about five times more potent than vitamin D3 and occurs in significant amounts. In milk, for example, it accounts for 75% of the total vitamin D activity as estimated by the calcium transport assay (38). 

In the analysis of foods that contain significant amounts of both naturally occurring toco-pherols and supplemental a-tocopheryl acetate, saponification, by hydrolyzing the esterified vitamin E, allows the total a-tocopherol content to be measured as a single peak by HPLC. It should be noted that if totally synthetic all-rac-a-tocopheryl acetate is the supplemental form used, its hydrolysis product, all-rac-a-tocopherol, is less biologically active than is naturally occurring RRR-a-tocopherol, making it impossible to calculate a potency value for the total vitamin E. This problem does not arise if the supplement used is / / / -a-tocopheryl acetate. 

HE Indyk. Simplified saponification procedure for the routine determination of total vitamin E in dairy products, foods and tissues by high-performance liquid chromatography. Analyst 113 1217-1221, 1988. 

Fruits and vegetables are the most common food sources for vitamin C (15-18). In food, vitamin C exists as two vitamers L-ascorbic acid (AA) and its oxidation product, dehydro-L-ascor-bic acid (DHAA) (Fig. 1) (15,17-19). Total Vitamin C is the sum of the AA and the DHAA contents. A stereoisomer, isoascorbic acid (IAA) is often added to food as an antioxidant. Both LAA and its oxidation product, dehydroisoascorbic acid (DHIAA), can interfere in Total Vitamin C determinations. 

Vitamin C continues to be the water-soluble vitamin upon which the bulk of the method development attention is focused. The HPLC methods published from 1992 to 1997 for total vitamin C... 

Table 1 HPLC Methods for Quantitating Total Vitamin C in Foods (C,8 Columns Fluorescence Detection)... 

Metaphosphoric acid + acetic acid extraction AA oxidized to DHAA using Norit total vitamin C as DHAA derivatized with o-phenylenediamine... 

AA + DHAA) ready-to-eat cereals pizza processed meat as internal standard when absent from sample cleanup as required with hexane to remove lipid material or n-butanol to remove starch S in series (150 X 4.6 mm + 250 X 4.6 mm, 5 gm, 100-A pore Polymer Laboratories). 4°C. 0.8 ml/min. CuCl2 derivatization of DHAA and DHIAA with o-phenylene-diamine. Fluorescence 350/430 nm (ex/em). Linear range = 3-2,000 ng. Recoveries 80-113% for total vitamin C (AA + DHAA) in a variety of food samples. Good agreement with results of AOAC International reference method. ... 

The six principal B6 vitamers are widely distributed in foods (102,103). They include pyridoxine (PN), pyridoxal (PL), pyridoxamine (PM), and their 5 -phosphate esters, pyridoxine phosphate (PNP), pyridoxal phosphate (PLP), and pyridoxamine phosphate (PMP) (Fig. 5). The predominate B6 vitamer in animal-based foods is PLP, whereas plant products generally contain PN and PM or their phosphorylated forms. Conjugated vitamers in the form of PN-glycosides have also been isolated from plant-based foods. Pyridoxal is readily converted to PM during cooking and food processing. Total vitamin B6 is the sum of the six principal vitamers inclusion of the conjugated forms depends on the extraction procedure. 

Total vitamin B6 has traditionally been assayed microbiologically (112). The HPLC methods have recently gained popularity as a result of their ability to distinguish between individual vitamers, including the glycosylated forms. Recent publications include both HPLC methods for total vitamin BA in foods and those for the individual vitamers (Tables 15-17). Much of the recent work has been dedicated to the direct determination of the glycosylated forms in the presence of the other vitamers. The simultaneous determination of vitamin B6 with one or more other vitamins is summarized later in Sec. XI. 

Results were lower than AOAC International microbiological method for total vitamin B6. 

Total Vitamin C extraction with 12.5% trichloroacetic acid reduce DHAA with 0.8% DL-homo-cysteine (minimum 40 1 excess of homocysteine DHAA). 

KY Dodson, ER Young, A-GM Soliman. Determination of total vitamin C in various food matrixes by liquid chromatography and fluorescence detection. J AOAC Int 75 887-891, 1992. 

AJ Speek, J Schrijver, WHP Schreurs. Fluorometric determination of total vitamin C and total isovitamin C in foodstuffs and beverages by high-performance liquid chromatography with precolumn de-rivatization. J Agric Food Chem 32 352-355, 1984. 

M Hoare, S Jones, J Lindsay. Total vitamin C analysis of orange juice. Food Australia 45 341-345,... 

M Chiari, M Nesi, G Carrea, PG Righetti. Determination of total vitamin C in fruits by capillary zone electrophoresis. J Chromatogr 645 197-200, 1993. 

Many vegetables and fruits, other than citrus, contain ascorbic acid. It was estimated that citrus fruits and tomatoes provided only 18% of the total vitamin C intake in the American diet during the decade of 1910. These two fruits supplied 41% of vitamin C in 1956-58 (6j. Today orange juice alone provides nearly 60% of the U.S. Recommended Daily Allowance (U.S. RDA) of vitamin C in the American diet (7). 

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