Multivitamin methods

Russell (44) and Ball (45) summarized multivitamin methods for foods that determined various combinations of thiamine, riboflavin, niacin, vitamin B6, folacin, and biotin. 

Thiamine Analysis by Multivitamin Methods with Potential to Improve Performance in the Future... 

The recently elaborated multivitamin methods for B vitamins assay using LC with MS/MS detection, micellar LC, LC-DAD/MS, LC/ESI-MS or LC-IDMS systems offer better sensitivity and selectivity, and can be potentially used for thiamine determination in fortified foods and infant formulas. These methods have potential to improve performance in the future. 

Particular attention has been paid in recent years for thiamine analysis with multivitamin methods with potential to improve performance in the future. These methods include up-do-date techniques of liquid chromatography and electrochemical methods based mainly on the voltammetric methods of analysis. 

The key step of a multivitamin method is the development of a simultaneous and quantitative extraction procedure. The intra- and intergroup heterogeneity of water-soluble vitamins makes it difficult to realize this goal. The application of an acid treatment, to hydrolyze the bound forms, can be used for simultaneous extraction of Bi, B2, B3, Bg, Bs,... 

Few analytical methods have been proposed for multivitamin determination in dietary supplements and food products by LC. The most emblematic multivitamin methods published in the last 10 years are summarized in Table 18.1. 

Preferably, high pressure Hquid chromatography (hplc) is used to separate the active pre- and cis-isomers of vitamin D from other isomers and allows their analysis by comparison with the chromatograph of a sample of pure reference i j -vitainin D, which is equiUbrated to a mixture of pre- and cis-isomers (82,84,85). This method is more sensitive and provides information on isomer distribution as well as the active pre- and cis-isomer content of a vitamin D sample. It is appHcable to most forms of vitamin D, including the more dilute formulations, ie, multivitamin preparations containing at least 1 lU/g (AOAC Methods 979.24 980.26 981.17 982.29 985.27) (82). The practical problem of isolation of the vitamin material from interfering and extraneous components is the limiting factor in the assay of low level formulations. 

It is known that Selenium catalyzes reaction of some dye reduction by Sulphide. On this basis spectrophotometric and test-techniques for Selenium determination are developed. Inefficient reproducibility and low sensitivity are their deficiencies. In the present work, solid-phase reagent on silica gel modified first with quaternary ammonium salt and then by Indigocarmine was proposed for Selenium(IV) test-determination. Optimal conditions for the Selenium determination by method of fixed concentration were found. The detection limit of Se(IV) is 10 ftg/L = 2 ng/sample). Calibration curve is linear in the range 50-400 ftg/L of Se(IV). The proposed method is successfully applied to the Selenium determination in multivitamins and bioadditions. 

Both WSV and FSV methods were rapid, with extraction and analysis completed in an honr. A single tablet was used to minimize sample volume and solvent nse. This is more acceptable for OTC prodncts. Further details and data were published elsewhere. Table 4 shows assay data on precision and recovery and Figure 7 shows HPLC chromatograms of WSV in standard solution and in multivitamin extracts. 

A large number of methods have been developed for analysis of water-soluble vitamins simultaneously in pharmaceutical products (like multivitamin tablet supplements). In fact, for these products no particular sample preparations are required and the high concentrations simplify the detection, enabling the use of UV [636]. The use of MS is also reported [637]. As well, Moreno and Salvado [638] reports also the use of a unique SPE cartridge (C18) for separating fat-soluble and water-soluble vitamins, which are, then analyzed using different chromatographic systems. 

HPLC is the method of choice for multivitamin determinations. Tables 25-27 summarize simultaneous HPLC determinations of multiple B vitamins in foods, published from 1992 to 1997. 

DeVries et al. (67) reported the summary of studies by a number of collaborating laboraties for the HPLC assay of vitamin D in multivitamin preparations. Saponification and a reverse-phase Merck LiChrosorb RP-8 column were used for sample cleanup. The analytical column was a Partisil , 5 nm column (Whatman, Clifton, N.J.) with hexane-amyl alcohol (99.65 0.35%) as the mobile phase. The cleanup procedure although a deparature from the usual analytical methods, was incorporated to ensure predictable, interference-free vitamin D assays (D2 and D3 co-elute). 

R. N. James and B. Boneschans, A reversed-phase HPLC method for the determination of niacinamide and riboflavin in dissolution samples of multivitamin-mineral combination capsules, Drug Dev, Ind. Pharm., 75 1989 (1992). 

Pharmaceuticals. In commerce, ascorbic acid is produced exclusively by synthesis (98). Because of its rather pure nature and high concentrations in vitamin-multivitamin tablets, analysis by conventional or sophisticated procedures can be performed easily. The USP provides a reference standard of L-ascorbic acid for assay purposes. The methods used can be chosen from the many discussed above. The method officially approved by the Association of Official Analytical Chemists is the micro-fluorometric procedure developed by Deutsch and Weeks (44). 

Intravenous vitamins and trace elements should be initiated on the first day of therapy and continued as a daily component of the PN solution. Children under age 11 should receive a vitamin product formulated for pediatric patients. Two multivitamin dosing schemas have been suggested for infants and children. One method recommends 2 mL/kg per day for infants weighing less than 2.5 kg and 5 mL... 

Multivitamin + Calcium Syrup (1 RDA of Vitamins/20 ml) 3. Chemical stability (20-25 °C HPLC methods)... 

The determination of vitamin in multivitamin preparations can be hampered by extraction difficulties but the use of sodium diethylene penta-acetic acid facihtates recoveries in excess of 90% (Walker et al., 1981). Subsequently, reversed phase ion-pair chromatography can be carried out using a mobile phase of 0.001 M hexanesulphonic acid in 1% acetic acid-methanol (75 25). Using this method, thiamine, niacinamide, riboflavin and pyridoxine can be quantitated. 

The first liquid chromatography-mass spectrometry (LC-MS) method was developed by Stokes and Webb (1999). Here, folate was separated using reversed-phase chromatography, detected in a single ion monitoring (SIM) mode and quantified using external standards [25]. These authors successfully identified and determined folic acid, tetrahydrofolate, 5-methyltetrahydrofolate, and formyltetrahydrofolate in multivitamins and foods. 

Figure 14.1 presents chromatograms of vitamins analysed in fruit drinks. The detection limit for thiamine hydrochloride deteetion was 9.2 ng/ml, whereas the limits for pyridoxine and cyanoeobalamin were 2.7 and 0.08 ng/ml, respectively. The proposed separation and detection procedure was applied sueeess-fully for quantitative evaluation of the studied B vitamins in pharmaeeutieal preparations and dietary supplements, and for routine control of multivitamin enriched foods. Based on those sueeessful results, we have developed also a method for analysis of vitamins Bg, B12 and Bi in seafood produets (Lebiedzinska et al. 2007). 

Vidovic, S., Stojanovic, B., Veljkovic, J., and Prazic-Arsic, L., 2008. Simultaneous determination of some water-soluble vitamins and preservatives in multivitamin syrup by validated stability-indicating high-performance liquid chromatography method. Journal of Chromatography A. 1202 155-162. 

Recent multivitamin analytical methods, including thiamine analysis recent development of high quality instrumental methods for thiamine analysis when a food sample is subjected to the multivitamin assay. The application of the methods to pharmaceutical materials is indicated. 

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