Infrared spectroscopy (IR)
Infrared spectroscopy is a robust and flexible method for testing both inorganic and organic matter without destroying the sample. The technique involves detecting the bonding vibrations of the molecules. This produces a spectrum in which characteristic bands can be assigned to functional groups. Even if this is not the case, the IR spectrum of a substance is distinctive and can be used as a “fingerprint”.
A special feature of this kind of spectroscopy is that it can be performed in all three states of matter. In the solid phase, we use attenuated total reflection (ATR) or even sample preparation as a classic KBr blank. The ATR technique can also be applied to liquid samples. For this process, we use a diamond or germanium crystal to ensure optimum sensitivity in the relevant wavelength range. Alternatively, it is also possible to move liquid samples or solutions – either in an IR cuvette or as a film between KCl plates – into the beam for testing. We also have a suitable measuring cell for analyzing gases.
IR spectroscopy is a fast, easy and reliable method, particularly in the field of identity screening. This is an important analytical step when testing raw materials, qualifying reference standards or applying for REACH approval, for example.
Identity screening can be carried out by comparing samples against a reference spectrum (from a database or pharmacopoeia, for example) or a reference substance (e.g. CRS or USP), or through interpretation.
CURRENTA Analytics makes use of GMP analytical practices in accordance with the regulations of Ph.Eur., USP or JP, with the appropriate prescribed sample preparations (e.g. ATR or as a KBr blank).
When testing unknown substances or materials, important structural information can be obtained quickly via IR spectroscopy. There are extensive databases that can be used to search for a measured spectrum. If the database search results in a hit, the identity can be clearly determined. Even similar database spectra can provide information about the substance or material class at this stage. A spectrum can also be interpreted for additional structural elucidation. Functional groups such as nitrile or carbonyl groups are represented by specific bands, which can be clearly identified in the structure. When combined with other methods such as MS and NMR, this approach can then be used to elucidate a structure.
Specific bands can also be used for quantification. This can be done relatively, by comparing samples with each other, e.g. in a stability test or by monitoring their reactions. It is also possible to externally calibrate the signal intensity.
Many substances show specific absorption in visible and ultraviolet light. Dyes and pigments in particular exhibit a unique UV spectrum. For many areas, a UV spectrum is therefore an essential part of a complete dataset. We offer this method in accordance with DIN EN ISO 17025, GLP and GMP.