Trace analysis
The trace analysis is a special discipline of chemical analysis . It tries to record substances in very low concentrations , ie to detect them or to determine them quantitatively.
properties
While the main and secondary components of a sample (for example a piece of a metal alloy) are in the two or one-digit percentage range, the trace range begins in the per thousand range and below. Below 1 ppm (corresponds to about 1 mg / l in the liquid phase) one speaks of the ultra-trace range. The concentration range examined in trace analysis comprises about six powers of ten of
In most cases, other components of the sample (the sample matrix) must first be removed during these analyzes, as these either react with the same reagent or prevent a reaction or mask the low concentration of the substance sought. We speak here of chemical interferences that have to be eliminated or compensated. On the one hand, careful sample preparation and on the other hand instrumental measures such as background correction in atomic spectrometry serve this purpose .
A wide range of instrumental methods is available for trace analysis . These include, in particular, the following chromatographic processes: gas chromatography , HPLC and thin-layer chromatography, often in combination with spectroscopic methods, mostly with mass spectroscopy .
Individual evidence
- ^ Herbert Feltkamp, Peter Fuchs, Heinz Sucker (editors): Pharmaceutical Quality Control , Georg Thieme Verlag, 1983, p. 351, ISBN 3-13-611501-5 .
- ↑ Eric Reid (Ed.): Assay of Drugs and other Trace Compounds in Biologicsl Fluids , North-Holland, Amsterdam, NY, Oxford (1976)