A Novel and Validated Chemical-Enzymatic Strontium Fractionation Method for Wheat Flour from Celestite Mining Area: the First Approach for Sequential Fractionation

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 quantification of the technique were 4.4 and 17.7 μg L −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 concentrations 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.