APPLICATION OF PTFE CLOSED-VESSEL MICROWAVE OVEN DIGESTION METHOD FOR ANALYSIS OF ELEMENTS IN FOOD / 营养学报

ABSTRACT

A method for the digestion of food samples by using PTFE closed-vessel microwave oven has been established. Six elements in the solution were determined by ICP-AES. The effects of various acid mixtures and digestion time were studied. 0.2 g of powdered samples dried for four hours at 80℃ were weighed and put into 50 ml PTFE digestion vessels. 2 ml of 70% HNO3 and 1 ml of 30% H2O2 were added to each sample digestion vessel. The screw caps were tightened and placed on the microwave oven PTFE turntable for 3 min at 100% full power (500W). When digestion was finished, the vessels were cooled for 10 min in a medical refrigerator at -25℃. The sample solutions were diluted to 25 ml with subboiling water. The contents of Ca, Mg, Mn, Fe, Zn and Cu in 3 standard reference materials were determined by ICP-AES. The results are in good agreement with certified values.