The significant progress achieved in modern instrumental analysis has led to a continuous lowering of detection limits and improved precision. This should in principle permit the reliable and extremely precise analysis of trace compounds mainly trace elements, at levels down to the lowest natural concentrations. However, the frequently observed very high discrepancies between the analyt­ ical results of different laboratories as well as the deviations from true values are, regrettably, still common in analytical practice. Basic methodological errors at the determination step can usually be minimized or even avoided by carefully per­ formed quality control measures - e. g. by interlaboratory comparisons and the proper use of certified reference materials. The most severe and often under­ estimated error sources, however, are those connected with the whole and often extremely complex sampling process, and also to a lesser extent, with sample pre­ paration prior to analysis. Thus, for these initial steps of an analytical procedure particular experience is needed, as well as a detailed knowledge of the interrela­ tions between these steps, which always have to be applied with the utmost care. In collaboration with a number of very experienced colleagues working in dif­ book has tried to contribute to a better ferent research areas, the editor of this understanding of these particular error sources and how they can be overcome in a series of training courses held during the last decade at the "Haus der Technik", Essen, Germany.

Table of Contents:
1 Sampling:an Introduction.- 1.1 General Remarks.- 1.2 Error Sources Prior to Total Element Determination.- 1.3 Sampling for Subsequent Determination of Chemical Species.- 1.4 Studies to Evaluate Sampling Errors.- 1.5 References.- 2 Human Specimens.- 2.1 Introduction.- 2.2 Human Specimens.- 2.3 Characterization.- 2.4 Sampling Procedures.- 2.5 References.- 3 Wet Precipitation:Rain and Snow.- 3.1 Introduction.- 3.2 Sampling Strategy.- 3.3 Sampling Equipment.- 3.4 Sampling in Winter.- 3.5 Sample Storage.- 3.6 Sample Preparation.- 3.7 Analytical Procedures.- 3.8 Results and Discussion.- 3.9 Conclusions.- 3.10 References.- 4 Sampling of Sea- and Fresh Water for the Analysis of Trace Elements.- 4.1 Introduction.- 4.2 Sample Handling.- 4.3 Sampling Procedures.- 4.4 Digestion.- 4.5 Typical Concentration Levels of Selected Trace Elements in the Aquatic Environment and Suitable Analytical Methods.- 4.6 Quality Assurance During Analysis and Data Evaluation.- 4.7 References.- 5 Soils and Soil Solutions.- 5.1 Introduction.- 5.2 Materials.- 5.3 Aspects of Soil Sampling and Recommendations for Its Realization….- 5.4 Sample Storage.- 5.5 Quality Control.- 5.6 Safety Precautions.- 5.7 References.- 6 Waste.- 6.1 Introduction.- 6.2 Theoretical Considerations for Sampling.- 6.3 Sampling and Storage.- 6.4 Decomposition and Analysis.- 6.5 Legal Requirements, Standards and Instruction Leaflets.- 6.6 Specific Problems.- 6.7 References.- 7 Collection, Preparation and Long-Term Storage of Marine Samples.- 7.1 Introduction.- 7.2 Tasks of the Environmental Specimen Bank.- 7.3 Collection.- 7.4 Sample Preparation.- 7.5 Conclusions.- 7.6 References.- 8 Biological Samples.- 8.1 Introduction: Ecological Basis – Information Content, Function and Indicative Value of Biological Specimens.- 8.2 QualityAssurance in Biological Sampling.- 8.3 Development of Specified Sampling Plans.- 8.4 Specific Problems of Sampling and Preparation of Biological Environmental Specimens.- 8.5 References.- 9 Sampling of Industrial Material (Sampling for the Balancing of Elements in the Cement Industry).- 9.1 Introduction.- 9.2 The Cement Clinker Burning Process.- 9.3 Sampling.- 9.4 Sample Preparation, Decomposition and Analysis.- 9.5 Checking Mass Flows.- 9.6 Conclusions.- 9.7 References.- 10 Food Products of Animal and Plant Origin.- 10.1 Introduction.- 10.2 Recommendations, Standards and Estimations of the Tolerable Intake of Toxic Metals via Food.- 10.3 Sample Collection.- 10.4 Sample Preparation.- 10.5 Homogenization.- 10.6 Decomposition Procedures.- 10.7 Analysis and Quality Control.- 10.8 Consumption Recommendations.- 10.9 References.- 11 Sample Preparation:an Introduction.- 11.1 General Remarks.- 11.2 Error Sources.- 11.3 Decomposition Directly Prior to Determination in Analytical Systems.- 11.4 Quality Assurance.- 11.5 References.- 12 Pressure Digestion: Apparatus, Problems and Applications.- 12.1 Introduction.- 12.2 Liner.- 12.3 Body.- 12.4 Safety Devices.- 12.5 Heating System.- 12.6 Conditions for Digestion.- 12.7 Completeness of Sample Decomposition.- 12.8 References.- 13 Microwave-Assisted Decomposition.- 13.1 Introduction.- 13.2 Microwave-Assisted Decomposition Apparatus.- 13.3 Comparison of Different Microwave-Assisted Digestion Systems.- 13.4 Criteria for the Evaluation of Microwave Digestion Systems.- 13.5 Conclusions.- 13.6 References.- 14 Decomposition Methods for the Electrochemical Determination of Elements.- 14.1 Introduction.- 14.2 Determination without Sample Decomposition.- 14.3 Oxidative UV-Digestion !..- 14.4 Mineralization by Oxygen.- 14.5 Open Wet Digestion.-14.6 Pressurized Digestion.- 14.7 Conclusions.- 14.8 References.- 15 Decomposition of Materials for Trace Analysis in the Cement Industry.- 15.1 Introduction.- 15.2 Decomposition Methods.- 15.3 Examples.- 15.4 References.