Matrix Normalization For Spatially Resolved Analysis Of Garnet In Laser Ablation-Inductively Coupled Plasma Mass Spectrometry

Laser ablation inductively coupled plasma mass Spectrometry (LA-ICP-MS) has been playing an increasingly important role in the in-situ trace elements analysis of geological sample. A valid calibration method is indispensable to equalize the matrix effect and the variety of sampling and transport in LA-ICP-MS, which are more serious than sampling in solution. Calibration was a main problem that astricted the extensively application of LA-ICP-MS. In order to improve the accuracy, all kinds of calibration methods were used, for example, the internal calibration,solid-liquid standard calibration,dried aerosols calibration,liquid ablation calibration,normalization calibration and so on, but the internal calibration was the most popular method up to now. We have to determinate the internal standard in advance with other micro analysis technique such as electron probe microanalysis (EPMA),X ray fluorescence Spectrometry and so on, because it is impossible to add internal standard in solid samples and the internal standard which belong to the samples is a common choose.The principals and scope of application of normalization calibration were discussed in details in this paper. Determination of internal standard in samples by other micro analysis technique is not needed in normalization calibration, which will reduce the cost of analysis significantly. Normalization calibration method with one more standard was achieved by relative sensitivity coefficient and its usability was proved by comparing the relative sensitivity coefficients in NIST612 and KL2-G. 43 elements were determined with this calibration method in natural garnet. The results were agreed well with the results obtained by internal calibrationGeologists are interested in the spatially distribution pattern of elements in the zoning geological samples. A series of uniform distribution spots were used to ablated to obtain the spatially distribution pattern of elements. This need the same spots in LA-ICP-MS and EPMA and certainly the cost and difficulty would increase, much time spending,annoying data processing and information losing are the worst.The spatially distribution pattern of elements in the zoning natural garnet were determined by normalization calibration method combining with raster ablation mode, The results agreed well with the results obtained by ablating spots traditionary. This method was proved to be a quicker,simpler and lower cost way in the determination of spatially distribution pattern of elements.The relative sensitivity coefficients were compared between laser ablating spots and raster. The results indicated that they agreed pretty well with each other while keeping the same depth. So the samples ablated in raster can be calibrated with standard ablated in spots in order to cut down the use of standard.