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Toxicité des substances chimiques, Analyse Toxicologique

Drugs Toxicological Analysis

Thin–layer Chromatography (TLC)

Introduction Thin–layer chromatography (TLC) is a widely used technique for the separation and identification of drugs. It is equally applicable to drugs in their pure state, to those extracted from pharmaceutical formulations, to illicitly manufactured materials and to biological samples. TLC as we know it today (see Fig 1) was established in the 1950s with… read more »

Mass Spectrometry

A mass spectrometer works by generating charged molecules or molecular fragments either in a high vacuum or immediately before the sample enters the high–vacuum region. Instruments typically maintain vacuums of about 10–6 mmHg, since ionised molecules have to be generated in the gas phase to be able to manipulate them using magnetic or electrostatic fields. In… read more »

Nuclear Magnetic Resonance Spectroscopy

Since its first observation in bulk phases in 1945, nuclear magnetic resonance (NMR) spectroscopy, has become one of the foremost methods for molecular identification, for evaluating detailed molecular structures, for understanding conformations and for probing molecular dynamics. If the measurements are carried out under appropriate conditions, NMR spectroscopy can also be used for quantitative analysis…. read more »

Raman Spectroscopy

Vibrational spectroscopy has been an integral tool for the identification and characterisation of drugs. When one thinks of vibrational spectroscopy, typically infrared (IR) techniques come to mind, not Raman spectroscopy. However, over the past 20 years a renaissance of the Raman technique has occurred, mainly through instrumentation development. These developments have led to unique applications… read more »

Near–infrared (NIR) Spectroscopy

The near–infrared (NIR) region of the electromagnetic spectrum extends from about 780 to 2500 nm (or 12800 to 4000 cm–1). It is therefore the part of the spectrum that exists between the red end of the visible spectrum and the beginning of the mid-infrared (IR) region. Its discovery by Herschel in 1800 was the first indication that… read more »

Infra–red Spectroscopy

Infra–red (IR) spectroscopy is the study of the scattering, reflection, absorption or transmission of IR radiation in the spectral range 800 nm to 1 000 000 nm (0.8 to 1000 μm). In older literature (pre–1970), IR radiation was referred to in terms of wavelengths as microns (μm). Nowadays, the wavenumber (ν̃) unit is used almost exclusively. The relationship between wavenumber… read more »

Spectrophotometry

Analytical absorption spectroscopy in the ultraviolet (UV) and visible regions of the electromagnetic spectrum has been widely used in pharmaceutical and biomedical analysis for quantitative purposes and, with certain limitations, for the characterisation of drugs, impurities, metabolites and related substances. By contrast, luminescence methods, and fluorescence spectroscopy in particular, have been less widely exploited, despite… read more »

Immunoassays

Immunoassays have a firm place among routine methods for the analysis of drugs in biological fluids and other matrices. The technique may be used by the smallest or largest of laboratories with methods that range from single–use point–of–care tests for the analysis of a single sample to fully automated systems capable of analysing thousands of… read more »

Colour tests

For some substances, the colour reaction with a particular chemical reagent may be quite specific, but it is much more common for the colour to be produced by a class of compounds. Moreover, compounds that do not fall into the class may also give colours. For some of the tests, the colour reactions can be… read more »

Colour tests methods

Amalic acid test (test for xanthines) Method Add to the sample a few drops of 10 M hydrochloric acid followed by a few crystals of potassium chlorate, and evaporate the mixture to dryness. Observe the colour of the residue then add two or three drops of 2 M ammonium hydroxide and again observe the colour. Indications A… read more »

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