Sample typical application
1. Water samples
- Drinking water: Internationally recognized techniques for water analysis have been brought together in ISO TC 147 . In examinations are carried out according to the Directive on Drinking Water for Observance of Limit Values for Heavy Metal Contents, anions and organic constituents.
- Effluents: According to the Law on Water Conservation and Effluent Discharge.
In the case of water samples a distinction is made between dissolved and undissolved components. Dissolved and undissolved components are separated by filtration through an 0.45μm membrane filter. The filtrate is then stabilized with 1 ml nitric acid per litre. The filter residue must be fused separately. Dissolved components can be distinguished as elementally or organically bonded components, which is also important for P analysis in water.
2. Clarification sludges, sludges
In effluent purification plants, in addition to effluent analysis, the clarification sludge is also frequently examined. Here again fusion of the sample and limit values are laid down by law.
Organically bonded heavy metals may elude determination by some analysis methods, the organic complexone must therefore be destroyed, which can be done inter alia by UV fusion.
3. Soil samples
Soil samples are frequently examined for heavy metals and halogene-containing substances in order to classify their suitability for dumping. In this case, elute products of the sample are produced and analysed. In Germany, classification is made into three classes for dumping.
4. Slags and geological samples.
Slags and geological samples, after being homogenized by fusion by melting, can be examined directly as solid substances by means of XRF. By dissolving the fused sample the solution can be used directly for AES or AAS. For trace analysis of eg. rare earth metals conversion of the samples to the dissolved form is unavoidable as only AES-ICP/MS or AAS give adequate LOD with the graphite tube technique.
Fusion of solid samples is an important aspect of sample preparation and must be carried out with care for race analysis. Selection of the method of fusion acid at atmospheric pressure or in a pressure bomb, the container material and the solvent will depend on the analytes. Possibilities are so varied that only a few important references can be indicated here.
5. Samples with organic matrix:
a. Chemical: alcohols, furans, PVC and other plastics
b. Oils and greases, refinery products
c. Biological samples: - foods of all kinds (sugar, flour, milk powder)
- plant samples ( spinach, lettuce, leaves)
- medical samples ( blood, serum, body fluid)
Separate fusion is necessary for each type of sample in order to obtain homogenization and remove the organic matrix. This applies in particular to organic solid in food, plants and medical samples.
Refuse analysis should be mentioned separately as it may be of very heterogeneous composition. Metals, also sulphur and chlorine, are determined from the residues of refuse incineration. Analysis makes it possible to draw conclusions regarding possible reclamation or danger to the environment.
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