A Novel and Validated Chemical-Enzymatic Strontium Fractionation Method for Wheat Flour from Celestite Mining Area: the First Approach for Sequential Fractionation Sema Bağdat 1 & Mehmet Hikmet Özkan 2 & Feyzullah Tokay 1 & Şeref Güçer 3 Received: 6 June 2018 /Accepted: 6 September 2018 # Springer Science+Business Media, LLC, part of Springer Nature 2018 Abstract In this study, a sequential Sr fractionation scheme was developed for wheat flour matrix. The lipid, water-soluble, and starch fractions were separated successfully. Total and fractionated Sr was determined by ICP-MS. The limits of detection and quan- tification of the technique were 4.4 and 17.7 μgL -1 , respectively. The distribution of Sr was varied between 21.2–31.3%, 28.1– 51.2%, and 22.9–49.3% in water-soluble, starch, and residue fractions, respectively. The lipid-bounded strontium was only determined for sample 3 as 0.42 mg kg -1 . Additionally, water-soluble content was divided into sub-fractions. The accuracy of the experimental procedure was tested with NIST-8436 durum wheat flour. The certified and sum of the fractionated Sr concen- trations were in good agreement with a recovery of 105.0% of the stated concentration. Moreover, simulated in vitro digestion methods were also applied to find out the bioaccessible Sr and to investigate the statistical correlation between fractions and gastrointestinal digests. Keywords Strontium . Fractionation analysis . Wheat flour . Bioavailability . ICP-MS Introduction Cereals are the basic and most important foodstuff in daily life for many parts of the world. Considering the wide range of growth conditions, wheat (Triticum aestivum L.) is one of the most cultivated crops among the other cereals such as rice, maize, barley, oats, rye, and millet. Besides economic impor- tance in global production, wheat and its products have an important role in a healthy diet. Wheat flour is an indispens- able and most consumed product of wheat in bread and pastry manufacture. It is the source of carbohydrate, fiber, protein, lipid, vitamins, and phytochemicals. Additionally, its potential contribution of essential elements to the diet cannot be underestimated (Shewry and Hey 2015). Considering its consumption routinely in daily life, the elemental composition of wheat and wheat flour attracts attention. There are several opportune and detailed papers on metal determination in wet- or dry-ashed wheat and wheat flour samples (Martins et al. 2015; Zhao et al. 2013). Moreover, different sample pretreatment investigations such as direct sampling (Araujo et al. 2008), slurry sampling (Araujo et al. 2007), pressed wheat flour pellet (Peruchi et al. 2014), and microwave-assisted extraction (Khajeh 2009) prior to detec- tion technique have been reported. Flame atomic absorption spectrometry (FAAS) (Araujo et al. 2007), electrothermal atomic absorption spectrometry (ETAAS) (Araujo et al. 2008), high-resolution continuum source electrothermal atom- ic absorption spectrometry (HR-CS ETAAS) (Santos et al. 2009), laser-induced breakdown spectrometry (LIBS) (Peruchi et al. 2014), energy dispersive X-ray fluorescence spectroscopy (EDXRF) (Peruchi et al. 2014), high-resolution inductively coupled plasma mass spectroscopy (HR-ICP-MS) (Zhao et al. 2013), inductively coupled plasma mass spectros- copy (ICP-MS) (Erdemir and Gucer 2016a, b), inductively coupled plasma optical emission spectrometry (ICP-OES) (Martins et al. 2015), and gamma spectroscopy (Bonafaccia et al. 2003) techniques have been utilized for determination of analytes in wheat or wheat flour after sample preparation step. Among these techniques, ICP-MS offers multi element * Sema Bağdat sbagdat@balikesir.edu.tr 1 Department of Chemistry, Faculty of Science and Arts, Balıkesir University, Çağış Campus, 10145 Balıkesir, Turkey 2 Republic of Turkey Ministry of Trade, İstanbul Custom Laboratory, Bakırköy, 34149 İstanbul, Turkey 3 Department of Chemistry, Faculty of Science and Arts, Uludag University, 16059 Bursa, Turkey Food Analytical Methods https://doi.org/10.1007/s12161-018-1362-3