Folates analysis

Since the 1970s numerous HPLC methods using lEC, RP and ion-pair chromatography have been proposed. In the last years, RP chromatography has become the most used method, thanks to its simplicity, sensitivity, and compatibility with different detection techniques. The stationary phases usually used are C18 or phenyl-bonded silica-based phases. More recently, alternative stationary phases, such as polar-embedded, polar endcapped, and perfluorinated phases, have been successfully tested for folate analysis [577]. The mobile phase is usually a mixture of phosphate or acetate buffer and acetonitrile or methanol. 

CA Martin. Folate analysis in foods. How accurate is it BNF Nutr Bull 20 8-15, 1995. 

L Vahteristo, PM Finglas, C Witthoft, K Wigertz, R Seale, I de Froidmont-Gortz. Third EU MAT intercomparison study on food folate analysis using HPLC procedures. Food Chem 57 109-111,1996. 

Wright AJ, Finglas PM, and Southon S (1998) Erythrocyte folate analysis a cause for concern Ciinicai Chemistry 44, 1886-91. 

FIG. 6. Expanded model of in vivo folate metabolism. Tbe pools are defined as follows 1, rapid turnover folate 6, slow turnover folate (tissues) 2, irretrievable losses by fecal excretion and catabolism 3, cumulative excretion of urinary folate 4, fractional (daily) excretion of urinary folate. Analysis was performed with parallel models for labeled and nonlabeled folate. 

Dietary folate intake determines folate nutritional status. It is therefore important to accurately measure folate in food using the best analytical platform currently available. In particular, folate analysis is confounded by several factors, such as the presence of many vitamers, low concentrations, physicochemical instability, and complex sample preparation [12]. It has been reported that the levels of endogenous 5-methyltetrahydrofolate and 5-formyltetrahydrofolate in canned chickpeas, a rich folate source, were 52 and 8 pg/lOO g, respectively [13]. Folate-fortified foods contain higher total folate concentrations than those found in natural folate-rich foods. We recently determined folic acid in Australian fortified bread varieties that was approximately 100 [tg/100 g [14]. 

Chandra-Hioe, M. V., Bucknall, M. R, and Arcot, J. 2011. Folate analysis in foods by UPLC-MS/MS Development and validation of a novel, high throughput quantitative assay folate levels determined in Australian fortified breads. Anal. Bioanal Chem. 401 1035-1042. 

Hyun, T. H. and Tamura, T. 2005. Trienzyme extraction in combination with micro-biologic assay in food folate analysis An updated review. Experimental Biology and Medicine. 230 444-454. 

Table 11.2 Principles of most frequent methods used for folate analysis.

Different methods are available for folate status measurement and for folate analysis in foods. 

Lin, Y., Dueker, S.R., and Clifford, A.J., 2003. Human whole blood folate analysis using a selected ion monitoring gas chromatography with mass selective detection protocol. Analytical Biochemistry. 312 255-257. 

Tracer Folates and SIDAs in Folate Analysis of Clinical Samples... 

As folate analysis is highly challenging, the accuracy of the single quantitation methods is controversial. Different methods often yield conflicting results and the true folate content remains open. Several method comparisons have been performed to shed light on this issue the more complex the sample matrix, the more disagreement has to be expected. 

In order to establish SIDAs as official reference methods, standard operation protocols have to be developed. In particular, the highly variable mass spec-trometric settings depending on the respective instruments retarded collaborative trials. However, in the area of mycotoxins, isotope dilution assays have been elaborated as reference methods and point to a way to implement SIDAs as official methods also in folate analysis (Rychlik and Asam 2008). This could lead to the establishment of reference materials with certified values obtained by SIDA. Lability of folates is still a roadblock but will be essential for quality assurance in accredited laboratories. 

Hyun TH, Tamura T. Trienzyme extraction in combination with microbiologic assay in food folate analysis an updated review. Exp Biol Med 2005 230 444-54. 

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