A method for rapid determination of arsenic species in vegetables using microwave-assisted extraction followed by detection with HPLC hyphenated to inductively coupled plasma-mass spectrometry

Driven by the significant need for characterization of the chemical speciation of arsenic in food, this work developed a method for rapid determination of four common arsenic species, namely, arsenite, arsenate, monomethyl arsenic acid, and dimethyl arsenic acid, in vegetables using microwave-assisted extraction, followed by detection with high-performance liquid chromatography hyphenated to inductively coupled plasma-mass spectrometry. Initial screening results showed that microwave-assisted extraction using 1% HNO3 exhibited the highest overall efficiencies for all arsenic species without causing significant degradation of the organic ones. With the aid of response surface methodology, the optimum conditions established for extraction of arsenic species from vegetables were: 500 mg of freeze-dried vegetable sample, extracted by closed vessel microwave-assisted extraction using 10 mL of 2% v/v HNO3 at 90 degrees C for 17 min. Application of the method in the analysis of 24 market vegetable samples indicates that the extraction efficiencies for total arsenic species were in the range of 91.4-106%. Arsenite and arsenate were found to be the predominant arsenic species in the vegetables, which suggests that vegetable consumption could be an important route of inorganic arsenic exposure for the population with a heavy vegetable diet in arsenic polluted regions.