An automated direct sample insertion-inductively coupled plasma spectrometer for environmental sample analysis

Simultaneous multielement determinations were carried out on microgram portions of environmental samples by direct sample insertion—inductively coupled plasma emission spectrometry (DSI-ICP-AES). The success of the determination was mainly due to the use of oxygen (20%) in the plasma operation. As a result, the samples were burned into the plasma facilitated the direct determination of elements with different volatilities in hard to vaporize matrices. The samples used in the study included stack flyash, kiln slag, and landfill cell leachate from a hazardous waste treatment plant. The results of these analyses obtained from DSI-ICP were compared with the results obtained from conventional solution nebulization ICP after microwave acid digestion.; An automatic sample insertion system with a 24-sample holder tray was developed for the DSI system in order to speed up the analysis and provide consistency for each insertion. A simple car antenna was employed as the insertion driver. Insertion positions were controlled by a magnet and a Hall sensor. A dedicated computer with Window based custom software was developed to control the autosampler and synchronize data acquisition operation.; A dual mode torch was developed to accommodate both conventional solution nebulization operation and direct sample insertion. By placing or removing a cap on the central tube of the torch, either solution or solid sample analysis could be performed on a single torch. The sensitivity and stability for the solution operation on the dual mode torch were equivalent to the original set-up.; The new DSI sub-system was mounted on a LECO Plasma-Array spectrometer. Linear calibration curves for As, Cd, Cu, Mn, Pb and Zn were obtained. The average relative standard deviation for multiple analyses of solution residues was around 6%.; The system was then used for the determination of volatile elements in different NIST SRMs that included soil, ash, food and leaves. The results indicated that the partial matrix matched solution residues were valid for calibration in the determination of volatile elements in solid samples. In general, the results obtained with DSI were in good agreement with NIST certified values.