Measurement of vitamin B 12 concentration: A review on available methods

The IIOAB Journal 01/2011; 2(2).
Source: DOAJ


Vitamin B12 is a water-soluble vitamin. It is one of the eight vitamins of vitamin B complex, needed for blood and cell maturation. It helps maintain healthy nerve cells and red blood cells, and it is needed in DNA replication. Its deficiency may cause megaloblastic anemia (amidst others health issues). For these and many similar reasons, it sometimes becomes necessary to measure its concentration. This article has carefully reviewed the different methods used for measuring vitamin B12 concentration, and the unique principles involved. The principles, basically, depend on the molecular structure of Vitamin B12 and its reactions with other substances. The methods include microbiological assay and spectrophotometric methods – these are old methods: they were the first available methods, but they are still in use for reference purposes. Another method is electroluminescent (ECL) which involves highly reactive materials. However, inductive-coupled plasma-mass spectrometry (ICP-MS) is a very important method, which is used routinely, even in many research. On the other hand, atomic absorption spectroscopy depends on measuring the amount of energy involved in the reaction; while radioimmunoassay (RIA) is a highly sensitive immunoassay technique. In addition, there are different techniques for separating and preparing samples to be used in the various measurement methods. High-performance liquid chromatography (HPLC) is used for non-validate analyst, while capillary-electrophoresis (CE) that have high resolving power than traditional electrophoresis, which when they are coupled with certain detectors they afford us another principle for measuring this vitamin. Choosing the best method for measuring vitamin B12 concentration depends on many factors – including the type of sample, purpose of the test, necessity of pre-processing, time limitations, cost, sensitivity, specificity.

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Available from: Ola Karmi, Jan 29, 2014
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    • "Therefore, the determination of the level of Vitamin B 12 is very important for blood, drugs, dairy products, and fermentation products . In literature, some techniques such as microbiological assay, radioisotope assay, immunoassay, mass spectrometry, electrochemiluminescence , spectrophotometry, electron spin resonance spectrometry, atomic absorption spectrometry, capillary electrophoresis , high performance liquid chromatography, fluorometry and electrochemical analysis are used for the determination of the level of Vitamin B 12 [36] [37] [38]. Electrochemical techniques such as cyclic voltammetry, differential pulse voltammetry, square-wave voltammetry, and amperometry have provided sensitive Vitamin B 12 detection. "
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    ABSTRACT: In this study, peptide nanostructures from diphenylalanine were synthesized in various solvents with various polarities and characterized with Scanning Electron Microscopy (SEM) and Powder X-ray Diffraction (PXRD) techniques. Formation of peptide nanofibrils, nanovesicles, nanoribbons, and nanotubes was observed in different solvent mediums. In order to investigate the effects of peptide nanotubes (PNT) on electrochemical behavior of disposable pencil graphite electrodes (PGE), electrode surfaces were modified with fabricated peptide nanotubes. Electrochemical activity of the pencil graphite electrode was increased with the deposition of PNTs on the surface. The effects of the solvent type, the peptide nanotube concentration, and the passive adsorption time of peptide nanotubes on pencil graphite electrode were studied. For further electrochemical studies, electrodes were modified for 30 min by immobilizing PNTs, which were prepared in water at 6 mg/mL concentration. Vitamin B12 analyses were performed by the Square Wave (SW) voltammetry method using modified PGEs. The obtained data showed linearity over the range of 0.2 μM and 9.50 μM Vitamin B12 concentration with high sensitivity. Results showed that PNT modified PGEs were highly simple, fast, cost effective, and feasible for the electro-analytical determination of Vitamin B12 in real samples.
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    • "Among them the HPLC/MS technique is probably the most frequently used to determine B12 in biological samples. Determination of B12 involves several analytical problems (Karmi et al., 2011). Analytes are present in food products at very low concentrations and have various chemical forms. "
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    ABSTRACT: Vitamin B12 is an animal origin nutrient of a substantial importance in human diet. Its concentration in foodstuffs is low and its chemical forms are diverse, which significantly hampers its precise determination. The determination method of choice is HPLC (high performance liquid chromatography) coupled with inductively-coupled-plasma mass spectrometry (ICP-MS). The main disadvantage of this method is high instrumentation cost and complexity of handling. The aim of this work was to develop a novel approach for determination of vitamin B12 bio-active forms in beef and beef liver. The proposed method comprises the following steps: (i) vitamin B12 is cleaved off from peptides using thermal denaturation in a weakly acidic environment; (ii) sample is cleaned-up using liquid-liquid extraction and reversed phase solid phase extraction; and finally (iii) vitamin B12 is determined using HPLC and single-quadrupole mass spectrometer with ESI source. Vitamin B12 concentrations in various beef meats were in the 2.84-3.95 μg 100g(-1) range. Average B12 concentration in beef liver was 153,60 μg 100g(-1) (n = 15). Major forms of B12 present in beef meat include adenosine cobalamin (AdoCbl) and in smaller quantities hydroxycobalamin (OHCbl). Major forms of vitamin B12 present in beef liver include OHCbl (48.2%), AdoCbl (33.8%), methylocobalamin (MeCbl, 16.3%), and cyanocobalamin (CNCbl, 1.7%). Thermal treatment noticeably decreases B12 the content in meat. Depending on conditions of treatment, B12 concentrations in the 1.04-2.20 μg 100g(-1) range were found in processed meats.
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