Infrared spectrometry is widely used in CTL as an identification method. Organic compounds as well as many inorganic materials whether solids, liquids or gases may be examined by means of this technique. Infrared spectra should be sufficient enough for direct comparison and rapid identification of unknowns in most cases. Infrared spectroscopy may serve also as a method to determine composition of mixtures and to quantify the content of single constituents inside.
Infrared microspectrometry, i.e. method using on-line attached microscope, permits to identify distinguishable structures in non-homogeneous mixtures. This technique is quite simple and precise enough for analysis of details of diameters as small as 0.1 mm or smaller. Microspectrometry may be applied for stains, fibres and single crystals examination serving especially in the forensic analysis. In addition to basic reflection and transmission modes, some more sophisticated techniques as diamond cell or micro ATR are acceptable.
FTIR systems represent important part of equipment of customs laboratories and they are supplemented with horizontal Attenuated Total Reflection (ATR) and Diffuse Reflection (DRIFT) and FTIR microscope.
IR spectrometry is in CTL aplied for:
- Confirmation of declared composition of products or articles.
- Characterisation and identification of unknown material or symplex.
- Differentiation of functional groups and structures of organic compounds.
- Quantitative analysis, e.g. determination of methylesters in mineral oil mixtures