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

超声波辅助的酶法提取，然后用稀酸洗涤，被引入大米样品的多元素分析中。通过电感耦合等离子体质谱法评估包括As，Cd，Mn和Zn在内的元素的回收率。实验参数包括酶的种类，酶的用量，超声功率和超声持续时间。最适条件是将胰酶以6.75 mg酶的量加入30 mg大米中，并以800 W的功率超声处理5分钟。整个提取过程可在20分钟内完成。使用三个认证的参考大米样品（GBW（E）100348，GBW10043和GBW10044）进行方法验证。砷，镉，锰和锌的回收率在82.2％至97.3％之间。四种元素的相对标准偏差均小于10％。最后，本方法成功地应用于实际样品的多元素分析。

图形概要