Automated infrared ashing with palladium nitrate as an ashing aid for the determination of selenium in plant foods by inductively coupled plasma mass spectrometry.

Based on the automatic light wave ashing instrument, palladium nitrate was used as an ashing aid for the first time to collect selenium in the process of food ashing pre-treatment, and a method for the determination of selenium in food by ashing method was established with inductively coupled plasma mass spectrometry. At the same time, the effects of magnesium nitrate, rhodium nitrate, and nickel nitrate as ashing aids on selenium collection were investigated using certified plant standard materials. The capture of selenium by magnesium nitrate, rhodium nitrate, and nickel nitrate as ashing aids did not exceed 50%. Using palladium nitrate as an ashing aid, six food standard materials were measured, with selenium recovery rates ranging from 97 to 106%. A complete analysis cycle can be completed within an hour. The method detection limit of selenium was 0.021 µg g-1, and the relative standard deviation of five measurements was less than 7%. The experimental results show that palladium nitrate is an excellent ashing aid for capturing selenium, and it is far superior to the other three aids. In addition, the mechanism of palladium nitrate as an ashing aid for capturing selenium was discussed.

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

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.