Ultrasound-Assisted Enzymatic Extraction Method for Multi-element Analysis of Rice

An ultrasound-assisted enzymatic extraction followed by a diluted acid washing was introduced into the multi-element analysis of rice samples. The recoveries of the elements including As, Cd, Mn, and Zn were evaluated by inductively coupled plasma mass spectrometry. The experimental parameters including enzyme type, enzyme dosage, ultrasound power, and duration of ultrasonication were investigated. The optimized condition was pancreatin with the dosage of 6.75 mg enzyme to 30-mg rice and ultrasonication for 5 min with the power of 800 W. The whole extraction procedure can be accomplished in 20 min. Three certified reference rice samples (GBW (E) 100348, GBW10043, and GBW10044) were used for method verification. The recoveries of As, Cd, Mn, and Zn ranged from 82.2 to 97.3%. The relative standard deviations of the four elements were all lower than 10%. Finally, the present method was successfully applied in the multi-element analysis of real samples. Graphical Abstract