Sample preparation methods Inorganic samples

How critically interdependent matrix and analytical methods can be is illustrated in the example of the analysis of a soil sample. Table 7.1 shows the method dependent certified values for some common trace elements. The soil had been subjected to a multi-national, multi-laboratory comparison on a number of occasions (Houba et al. 1995) which provided extensive data. The data was subjected to a rigorous statistical program, developed for the USEPA by Kadafar (1982). This process allowed the calculation of certified values for a wide range of inorganic analytes. Uniquely, for the soil there are certified values for four very different sample preparation methods, as follows ... 

APPENDIX VIII SOME COMMON INORGANIC AND ORGANIC SAMPLE PREPARATION METHODS USED IN ARCHAEOLOGY... 

See also Environmental and Agricultural Applications of Atomic Spectroscopy Environmental Applications of Electronic Spectroscopy Geology and Mineralogy, Applications of Atomic Spectroscopy Inorganic Compounds and Minerals Studied Using X-Ray Diffraction IR and Raman Spectroscopy Studies of Works of Art IR Spectroscopy Sample Preparation Methods MRI of Oil/Water in Rocks X-Ray Fluorescence Spectrometers. 

Table 1.13, which lists the main techniques used for polymer/additive analysis, allows some interesting observations. Classical extraction methods still score very high amongst sample preparation techniques on the other hand, not unexpectedly, inorganic analysis methods are not in frequent use for separation purposes... 

Sample preparation for the common desorption/ionisation (DI) methods varies greatly. Films of solid inorganic or organic samples may be analysed with DI mass spectrometry, but sample preparation as a solution for LSIMS and FAB is far more common. The sample molecules are dissolved in a low-vapour-pressure liquid solvent - usually glycerol or nitrobenzyl alcohol. Other solvents have also been used for more specialised applications. Key requirements for the solvent matrix are sample solubility, low solvent volatility and muted acid - base or redox reactivity. In FAB and LSIMS, the special art of sample preparation in the selection of a solvent matrix, and then manipulation of the mass spectral data afterwards to minimise its contribution, still predominates. Incident particles in FAB and LSIMS are generated in filament ionisation sources or plasma discharge sources. 

In this method, inorganic lead in seawater samples are converted to tetra-ethylead using sodium tetraethylboron (NaB(C2H5)4) which is then trapped in a graphite furnace at 400 °C. Quantitation is achieved by using a simple calibration graph prepared from aqueous standards. An absolute detection limit of (3relative standard deviation. 

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