A Novel Method for Chlorine and Sulfur Determination in Gluten-Free and Gluten-Containing Edible Flours from Different Raw Materials and Countries

A novel and eco-friendly analytical method using microwave-induced combustion (MIC) and ion chromatography (IC) was proposed for the determination of chlorine and sulfur in corn, potato, rice, and wheat edible flours from several countries (Austria, Brazil, Belgium, Ecuador, Poland, and Turkey). Agreement with certified reference material (NIST 1568a, rice flour) was 97% for Cl and 90% for S. The limits of quantification were 5.2 μg g−1 for Cl and 1.5 μg g−1 for S. The content of elements did not vary significantly between wheat flours from different countries. The highest concentration of Cl and S was found in wheat flours (Cl: 424 to 714 μg g−1; S: 1020 to 1477 μg g−1) when compared with corn (Cl: 330 to 408 μg g−1; S: 751 to 895 μg g−1), rice (Cl: 204 to 219 μg g−1; S: 1007 to 1041 μg g−1), and potato starch flours (Cl < 5.2 μg g−1; S: 8.44 to 11.2 μg g−1). It is important to highlight that the proposed method presents low limits of detection, low relative standard deviations, and high sample throughput, which indicates that it is an excellent alternative as a new analytical method that could be used for routine analysis of edible flours.