Niacin extraction

In order to extract niacin and to release the chemically bound forms, a digestion step is necessary as part of the sample preparation. 

The SP procedure of water-soluble vitamins from multivitamin tablets is particularly challenging due to the diverse analytes of varied hydrophobicities and pfC. Water-soluble vitamins (WSVs) include ascorbic acid (vitamin C), niacin, niacinamide, pyridoxine (vitamin B ), thiamine (vitamin Bj), folic acid, riboflavin (vitamin B2) and others. While most WSVs are highly water soluble, riboflavin is quite hydrophobic and insoluble in water. Folic acid is acidic while pyridoxine and thiamine are basic. In addition, ascorbic acid is light sensitive and easily oxidized. The extraction strategy employed was a two-step approach using mixed solvents of different polarity and acidity as follows ... 

Either acid or alkaline hydrolysis can be applied, converting nicotinamide to nicotinic acid. Alkaline hydrolysis releases also the unavailable vitamers providing the estimation of the total niacin content. Acid hydrolysis, instead, is slower than alkaline hydrolysis therefore the former is usually coupled with enzymatic digestion by using takadiastase, papain, and clarase. Extraction with water and dilute sulfuric or hydrochloride acid has been applied to release the vitamers from the matrix without degrading nicotinamide [598]. 

More recently [635], a unique extraction step in supplemented foods, by using hot water and a precipitation solution, following by HPLC-ELD/UV analysis has been performed for the simultaneous determination of pyridoxine, thiamine, riboflavin, niacin, pantothenic acid, folic acid, cyanoco-balamin, and ascorbic acid. The mobile phase consisting of phosphate buffer and methanol has been modified in order to perform ion-liquid chromatography by adding l-octanesulfonic acid sodium salt. Furthermore, triethylamine has been also added to improve peak symmetry. 

Due to the relative stability of the niacin vitamers, either acid or alkaline hydrolysis can be used to convert nicotinamide to nicotinic acid for quantitation of both vitamers as nicotinic acid (9,44). Acid hydrolysis is used to quantitate biologically available niacin. Alkaline hydrolysis releases both the biologically available and the unavailable vitamers and provides an estimate of the total niacin content. Because alkaline hydrolysis is much faster than acid hydrolysis, the latter is usually supplemented with enzymatic hydrolysis. The most common enzymes are takadiastase, papain, and clarase. On occasion, organic solvents such as methanol have been used to extract free nicotinic acid. 

Total niacin Fortified foods Sulfuric acid extraction Analytical PRP-X100 Isocratic dilute UV absorbance External standardization. 101... 

Total niacin Yeast spreads Extraction in aqueous... 

Malt extract is a good source of niacin, iron, and potassium... 

Preuss, H.C., Bagchi, D., Bagchi, M., Rao, C.V.S., Satyanarayana, S. and Dey, D.K. (2004) Efficacy of a novel, natural extract of (-)-hydroxycitric acid (HCA-SX) and a combination of HCA-SX, niacin-bound chromium and Cymnema syivestre extract in weight management in human volunteers a pilot study. Nutrition Research 24(1), 45-58. 

A small fraction of the niacin in niacytin may be biologically available as a result of hydrolysis by gastric acid. About 10% of the total is released as free nicotinic acid after extraction of maize or sorghum meal with 0.1 mol per L of hydrochloric acid, and Carter and Carpenter (1982) have shown that about 10% of the total niacin content of maize is biologically available to humans beings. 

Some itamirLS are water soluble, while others are fat soluble. This classification is valuable as it indicates whether the vitamin is likely to be absorbed similarly to lipids or like other water-soluble nutrients. The fat-soluble vitamins are A, D, E, and K. The water-soluble vitamins arc ascorbic acid, biotin, folate, niacin, pantothenic acid, riboflavin, thiamin, vitamin B i, and vitamin B 2. The classification is also valuable, as it helps chemists decide on the best way to extract and analyze a particular vitamin in foods and biological tissues. Aside from having some bearing on the path ways of absorption and distribution throughout the body, the question of whether a particular vitamin is fat soluble or water soluble has little or no relevance to its function in the body. 

Kyo-Chrome AGE Cholesterol Formula, 400-mg extract powder, niacin 20 mg, chromium 200 pg... 

Elucidation of the structure of the B vitamins resxilted in the development of analytical chemical methods. Such methods are useful in industries manufacturing vitamins in which measurements of microgram to milligram quantities are routine, but these same methods are often not applicable to biological fiuids that contain as little as picogram quantities. Colorimetric and fluorometric techniques have been developed for niacin and folate, but these techniques require complicated extraction procedures and blank determinations. They also suflFer from lack of specificity, and the results are often altered by interference from biologically inactive materials that occur naturally or are produced during extraction (16,20). 

Vinson, J.A. et al.. Beneficial effects of a novel IH636 grape seed proanthocyanidin extract and a niacin-bound chromium in a hamster atherosclerosis model. Mol. Cell Biochem., 240, 99, 2002. 

Windahl, K. W., Trenerry, V. C., and Ward, C. M., The determination of niacin in selected foods by capillary electrophoresis and high performance liquid chromatography Acid extraction. Food Chem., 65, 263, 1998. 

Niacin is found in foods as nicotinic acid and nicotinamide, which are the free forms, and as the coenzymes nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate. Niacin is stable and can be extracted into acids or alkalis. Niacin has been determined by CE in a range of food matrices, such as meat, fish, fruit, and vegetables, and CE is generally found to be faster and more cost-effective in comparison to established HPLC methods. 

The adsorption of thiamin, riboflavin, and niacin, components of the B vitamin present in Aspilia Africana extract, was investigated [50]. Those molecules may adsorb through a soft epitaxy mechanism on the metal surface, with accommodation of the molecular backbone in characteristic epitaxial grooves on the metal surface (Fig. 5.3). 

Coverage includes B vitamins and folate in the context of a historical background, disease, cardiovascular effects and the importance of vitamins in biochemistry as illustrated by a single vitamin. Thereafter there are chapters on the chemistry and biochemistry of thiamine, riboflavin, niacin, pantothenic acid, pyridoxine, biotin, folate and cobalamin. Methodical aspects include characterization and assays of B vitamins and folate in foods of all kinds, dietary supplements, biological fluids and tissues. The techniques cover solid-phase extraction, spectrofluorimetry, mass spectrometry, HPLC, enzymatic assay, biosensor and chemiluminescence. In terms of fimction and effects or... 

Table 19.3 contains results of niacin determinations of some milk samples, again in MRM mode, including RM 8435 (whole milk powder) from NIST. These samples are not fortified and contain niacin at considerably lower levels than the samples in Table 19.2. Precision obtained for these samples is in the range 1-5% RSD. An example of an extracted ion chromatogram for commercial milk Brand F is shown in Figure 19.2. The USDA Nutrient Database for Standard Reference, Release 23 (US Department of Agriculture 2010) lists a value of 0.89 ppm niacin for milk, whole, 3.25% milkfat and a value of 0.84ppm niacin for milk, producer, fluid, 3.7% milkfat . We thus assume that expected values for niacin for whole milk samples are near 1 ppm. The levels...

Figure 19.2 Extracted ion chromatograms obtained for commercial milk sample Brand F spiked with D4-niacin. These extracted ion chromatograms illustrate that the retention times are essentially the same for natural and D4-niacin, and that even at relatively low concentrations signal-to-noise ratios (S/N) are good and the chromatograms are essentially free of interfering signal. To obtain the chromatograms, 5 microlitres (pL) of a sample that was about 90 ppb each in natural niacin and D4-niacin were injected. The milk sample from which the sample was prepared was determined to be about 1 ppm in niacin.

The IDMS method using an acid digestion and reversed phase LC as described here should be applicable to niacin measurement in a wide variety of food matrices, but IDMS treatments should also be valid when using alkaline digestions, extractions and other chromatographic approaches. The key methodological requirement is that the labelled spike achieves equilibration with the analyte to be measured. 

Juraja, S.M., Trenerry, V.C., Millar, R.G., Scheelings, P., and Buick, D.R., 2003. Asia Pacific Food Analysis Network (APNFAN) Training Exercise The determination of niacin in cereals by alkaline extraction and high performance liquid chromatography. Journal of Food Composition and Analysis. 16 93-106. 

LaCroix, D.E., Wolf, W.R., and Vanderslice, J.T., 1999. Determination of niacin in infant formula and wheat flour by anion-exchange liquid chromatography with solid phase extraction cleanup. Journal of AOAC International. 82 128-133. 

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