Green and fast ultrasound-assisted extraction procedures for Fe, Mn, Mg and Ca analysis in cane syrups by FAAS

New methodologies for the analysis of Fe, Mn, Mg, and Ca content in cane syrups using FAAS combined with ultrasound-assisted extraction (UAE) were developed and validated. For multivariate optimization of UAE, a simplex-centroid mixture design and individual desirability functions were applied to achieve the best composition of extraction solvents (HNO3, HCl, and water). Under optimal conditions of ultrasound-assisted extraction (100 W, 37 kHz, 10 min, 5.0 mL of extraction solvent (ultrapure water for Fe and Mn and HNO3:H2O (75:25%, v/v), corresponding to a 1.19 mol L−1 HNO3 solution for Mg and Ca)), method validation showed good linearity, confirmed by regression analysis, and low LOD and LOQ values of 0.266–0.284 μg g−1 and 0.114–0.861 μg g−1. Estimates of repeatability and mean precision (RSD = 0.44–2.11%), Horrat values (0.07–0.26), and assessment of trueness by comparing sample preparation methods using a paired t-test demonstrated the excellent precision and trueness of the developed methods. The methods were applied to twenty-five cane syrup samples, and the results of the multivariate analysis showed that the metal ions can be used as indicators of geographical origin or contamination during manufacturing or processing, thus helping to ensure the food quality and safety of this sweetener.