Development and characterization of an automated direct sample insertion inductively coupled plasma atomic emission spectrometry system

A new direct sample insertion (DSI) device that can be used vertically with inductively coupled plasma atomic emission spectrometry (ICP-AES) or horizontally with ICP mass spectrometry (ICP-MS) has been designed, and an automated ICP-AES system has been developed around this DSI device. The automated DSI-ICP-AES system was characterized by using microliter volumes of liquids and milligram amounts of powders. Analysis of solids with minimum pretreatment was a key goal in developing this system, and several calibration methods for powders were investigated. Examples of these are liquid standards, a few milligrams of different reference material or a different weight of the same material and standard additions of liquids onto a powder in the cup. Sample handling, weighing, sampling, and homogeneity concerns were partially addressed by using slurries. In addition, slurry DSI-ICP-AES for botanical, geological, and biological powdered reference materials is briefly described. Carbide formation is a key chemical limitation of graphite-cup DSIs, and it was addressed by using in situ chemical modification by mixing SF6 with the plasma gases.