Simultaneous determination of arsenic, cadmium and lead in plant foods by ICP-MS combined with automated focused infrared ashing and cold trap

•Automated infrared ashing was used for ICP-MS determination of As, Cd and Pb.•Charring, ashing, dissolution and homogenization was automatically completed.•Cold trap and the semi-sealed ashing tube improve the recovery of volatile elements. A fully automated focused infrared lightwave ashing sample preparation system was proposed and applied to the pretreatment of volatile arsenic, cadmium and lead in plant foods prior to inductively coupled plasma mass spectrometry (ICP-MS) determination. All the steps of ashing pretreatment were automatically accomplished within forty minutes. Gold-plated infrared quartz tubes produced focused infrared to supply a rapid heating. Ozone was used to accelerate sample carbonization. A cool trap was used to capture volatile arsenic, cadmium and lead. Three certified plant food reference materials were determined. The recoveries of the three elements were between 90% and 107%. Five real plant foods were analyzed by the proposed method and microwave digestion. The results showed no significant difference.