Folic Acid-fortified Flour: Optimised and Fast Sample Preparation Coupled with a Validated High-Speed Mass Spectrometry

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Folic Acid-fortified Flour: Optimised and Fast Sample Preparation Coupled with a Validated High-Speed Mass Spectrometry Analysis Suitable for a Fortification Monitoring Program Maria V. Chandra-Hioe & Martin P. Bucknall & Jayashree Arcot

Received: 8 October 2012 / Accepted: 19 December 2012 # Springer Science+Business Media New York 2013

Abstract In Australia, folic acid (FA) has been mandatorily added to bread making flour (non-organic wheat flour) since September 2009. The objective of FA fortification is to reduce the prevalence of neural tube defects. This study validated a quantitative assay to determine FA in fortified flour using ultra-performance liquid chromatographytandem mass spectrometry (UPLC-MS/MS). For this purpose, a procedure of aqueous extraction followed by solid phase extraction (SPE) was developed for isolating FA from fortified flour samples. SPE using phenyl cartridges is more selective and avoids the high sodium concentrations used to elute FA from ion exchange sorbents. The validated method is linear over the range 0.024–14 μg/g flour. Absolute recovery of FA was 89 %; inter-day variability coefficient of variation (CV) was 11 % and limit of detection (LOD) was 9.8 ng/g flour. The experimental data revealed that the majority of commercially fortified bread premixes and flour had mean FA concentrations lower than the minimum mandated level of 200 μg/100 g flour. The findings of this study

M. V. Chandra-Hioe (*) : J. Arcot Food Science and Technology, School of Chemical Engineering, University of New South Wales, Sydney 2052, Australia e-mail: [email protected] J. Arcot e-mail: [email protected] M. P. Bucknall Bioanalytical Mass Spectrometry Facility, Mark Wainwright Analytical Centre, Sydney, Australia e-mail: [email protected] M. P. Bucknall School of Chemistry, University of New South Wales, Sydney 2052, Australia

support the need for regular monitoring of actual fortification levels by the Australian States and Territories. Keywords Folic acid . Fortified flour . Sample extraction . SPE . Validation . UPLC-MS/MS

Introduction Vitamins required to sustain the human body's homeostasis constitute a dietary need because they are either not synthesised endogenously or not synthesised in adequate amounts. One of the essential micronutrients is watersoluble folate (vitamin B9), which can be sourced from foods high in folate like beans, legumes and leafy green vegetables. Pteroyl-L-monoglutamic acid, generally known as folic acid (FA), is present naturally in very low concentrations in food. Synthetic FA is added commercially to fortify or to enrich food in folate and is used in dietary supplements. FA is one of the diverse forms of folate; its chemical structure consists of three distinct moieties: a bicyclic, heterocyclic pteridine ring, named 6-methylpterin; para-aminobenzoic acid (PABA); and glutamic acid. Many Australian ‘ready to eat’ breakfast cereals are voluntarily enriched with FA, whilst bread (non-organic wheat grains) is mandatorily fortified, making these foods