Abstract
Food is the main way of intake of trace elements by human, and rice is the most important food that Taiwanese eat every day. This research aimed to construct a simple, fast and reliable method to analyze multi trace elements in rice by using inductively coupled plasma mass spectrometer, ICP-MS. Prior to instrumentalanalysis, microwave digestion system was successfully applied to decompositionof samples by using 6 ml of concentrated nitric acid and 3 ml of 30 % hydrogen peroxide under 10 minutes and 110 ℃digestion. To validate the proposed method, three Standard Reference Materials from the National Institute of Standard and Technology,were analyzed, and the recovery of each element was in the range of 80-120 %. The measurement uncertainty was alsoevaluated by top-down approach, and the results are in the range of 0.08-5.08 mg/kg. Afterwards, 75 rice samples from different regions in Taiwan, 25 different species of fish samples and 42 pork samples were collected as field research samples. Finally, the provisional tolerable weekly/daily/monthly intake of adults and elementary childrenwere estimated. All of the 75 rice samples and 42 pork samples are under the regulation for heavy metals set by Food and Drug Administration. Further speciation method is needed for fish samples to check the concentration of inorganic arsenic and methyl mercury. Average weekly/daily/monthly intake of each element of elementary children is under the regulation set by World Health Organization, but the weekly intake of arsenic and mercury of adults are above the regulation.