Ultrasound-assisted digestion using choline chloride-oxalic acid deep eutectic solvent for macro and microelements determination in rice by ICP-OES

Abstract

Abstract A rapid, straightforward, and environmentally friendly method was developed for the extraction of K, Na, Ca, Mg, Fe, Mn, Cu, Zn and P from rice samples using ultrasound-assisted deep eutectic solvents (DESs). The investigation focused on deep eutectic solvents derived from choline chloride and oxalic acid. The response surface methodology, based on the Box-Behnken design, was employed to determine the optimal conditions of the significant parameters. The determination results of the reference samples revealed a relative error ranging from -8.3% to 3.8%, while the relative standard deviation remained below 5.5%. F-test and t-test results indicated that there was no statistically significant difference observed between the accuracy and precision of the method proposed in this study and the microwave digestion method for determining actual rice samples. The proposed method exhibits advantages over classical microwave-assisted digestion procedures based on concentrated acids, considering critical parameters such as cost, green chemistry, and analyst safety.