Gas chromatography Fourier transform infrared spectroscopy (GC/FT-IR) has been examined as a new forensic drug identification technique. The method is found to be specific for many closely related isomers including cocaine and pseudococaine or phentermine and methamphet-amine. Distinguishing some isomers may require spectral subtraction or examination of band positions. The useful range of GC/FT-IR sensitivities was determined to be from 5O to 500 nanograms per component.
Supercritical fluid extraction using 100% carbon dioxide is able to remove antioxidant additives from flaked polyethylene. SFE appears to be more selective for the lower-range low-MW polymer than Soxhlet-type extraction. This yields a chromatogram with less interference from low-MW polymer peaks in the region where the additive components elute. Infrared detection is able to locate peaks corresponding to distinct types of additives by generating chromatograms from chemically specific regions of the SFC/IR data. Infrared spectra are sufficient for identification of additives and determination of the oxidation state of phosphorus-containing antioxidants.
The six insecticidally active components in a commercial preparation of pyrethrin extract are separated by capillary gas chromatography (GC) and by capillary supercritical fluid chromatography (SFC). Thermal degradation of pyrethrin I and II are observed under the GC conditions required to separate the pyrethrin components. The use of shorter columns and thinner stationary phase coatings reduce the amount of degradation but cannot eliminate degradation of pyrethrin II. The SFC chromatograms, obtained under thermally mild conditions, show that all components including pyrethrin II elute without degradation. Infrared spectra of cinerin I & II, jasmolin I & II, and pyrethrin I & II are obtained using a flow through SFC/IR detection cell. Spectra clearly reveal the structural differences needed to distinguish and identify the components in the extract.
The analysis of solvents for both purity and component identifications is routinely performed by gas chromatography (GC). Coupling it with the latest FT-IR systems results in a technique which yields ppm sensitivity and excellent library search results.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.