Microwave-assisted robotic method for the determination of trace metals in soil

A fully automated method for the determination of metals (Fe, Cu and Zn) in soil based on the use of a robotic station is reported. The time-consuming sample digestion traditionally performed by stirring has been substituted by microwave-assisted digestion by including a focused microwave digester as a module of the robotic station that was controlled by the robot. Thus, the digestion step was shortened from 2 h to 3 min. After digestion, the sample is transported to an atomic absorption spectrometet for measurement either after dilution by the robot or by aspiration to feed a valve-loop in a flow-injection system where dilution is adjusted as required depending on the concentration of the metal concerned. Both dilution methods have proved to yield reproducible results (R.S.D. < 2%).