Supercritical fluid chromatography absorption

Supercritical fluid chromatography Thin-layer chromatography Atomic absorption spectroscopy Nuclear magnetic resonance spectroscopy Mass spectrometry Fourier transform infrared spectrometry... 

Atomic absorption spectrometry (organomercury and tin compounds) and gas chromatography (organoarsenic, lead, mercury and tin compounds) are the two most popular techniques (Table 1.11(c)) while supercritical fluid chromatography is making some inroads (organotin compounds). 

Spectro- photometry Atomic absorption spectrometry Supercritical fluid chromatography GLC... 

The most convenient way to prepare thermosetting gel is to add reactive monomers such as acrylate and metacrylate of the alkylene oxide to the liquid electrolyte and cross-link by irradiating heat, ultraviolet, or electron beam. The residual monomer can be detected by methods of infrared absorption measurement (on basis the peak of 1638 cm ), supercritical fluid chromatography, and photo-DSC (optical difference scanning thermal analysis). 

Supercritical fluid chromatography (SFC) is a hybrid of GC and HPLC in which the mobile phase is a compound that is held above its critical temperature Tc) and critical pressure Pc)- By far the most common compound that is used as an SFC mobile phase is CO2, for which Tc 31°C and Pc 73 atm. The diffusivities of many compounds in supercritical CO2 are high enough that either packed-column or open-tubular columns may be used. The solvent strength of supercritical CO2 is roughly intermediate between those of n-hexane and benzene thus, many compounds that are too nonvolatile to be separable by GC can be separated by SFC. Detection of solutes separated by SFC is also easy, since GC detectors such as the FID and HPLC detectors such as UV absorption detectors can both be used. 

Absorption spectroscopy, transmission spectroscopy with integrating sphere, liquid chromatography, gas chromatography, supercritical fluid chromatography... 

There are a variety of detectors that will be found suitable for the detection of organic compounds in supercritical fluid chromatography. Carbon dioxide is the most widely used fluid and has the advantage of being transparent in the ultraviolet part of the spectrum to 190 nm. Variable wavelength UV absorption detectors used for liquid chromatography may be employed for SFC but they must incorporate a cell that can withstand the very high pressures employed in the technique. A number of UV detector manufacturers produce suitably modified instruments for use with SFC. 

Steady-State Solvatochromism. The majority of the reports on supercritical fluid solvation have used steady-state solvatochromic absorbance measurements (21-28). The original aim of these experiments was to determine the solvating power of supercritical fluids for chromatography and extraction (SFC and SFE) (26,28). To quantify solvent strength, researchers (21-28) adopted the Kamlet-Taft x solvent polarity scale (50-55). This scale best correlates solvatochromic effects on a- x and x- x electronic absorption transitions. 

D. E. Martire and R. E. Boehm, Unified molecular theory of chromatography and its application to supercritical fluid mobile phases. 1. Fluid-liquid (absorption) chromatography , J. Phys. Chem. 91 2433-2446 (1987). 

D. E. Martire, Unified theory of absorption chromatography gas, liquid and supercritical fluid mobile phases , J. Liq. Chromatogr. 10 1569-1588 (1987). 

Figure 6.1 Bar-graph of MeHg in CRM 580. The results correspond to six replicate determinations as performed by different laboratories using various methods. MEANS indicates the mean of laboratory means with 95% confidence interval. Abbreviations-. CVAAS, cold vapour atomic absorption spectrometry CVAFS, cold vapour atomic fluorescence spectrometry ECD, electron capture detection GC, gas chromatography HPLC, high-performance liquid chromatography ICPMS, inductively coupled plasma mass spectrometry MIP, microwave induced plasma atomic emission spectrometry QFAAS, quartz furnace atomic absorption spectrometry SFE, supercritical fluid extraction.

A very recent volume edited by Berthed (2002) is on countercurrent chromatography - the support-free liquid stationary phase. Ebdon et al. (1987) review directly coupled liquid chromatogramphy-atomic spectroscopy. The review by Uden (1995) on element-specific chromatographic detection by atomic absorption, plasma atomic emission and plasma mass spectrometry covers the principles and applications of contemporary methods of element selective chromatographic detection utilizing AA, AES and MS. Flame and furnace are considered for GC and HPLC, while MIP emission is considered for GC and ICPAES for HPLC. Combinations of GC and HPLC with both MIPAES and ICPAES are covered and supercritical fluid chromatographic (SFC) and field flow fractionation (FFF) are also considered. 

See also-. Extraction Supercritical Fluid Extraction. Forensic Sciences Gunshot Residues Thin-Layer Chromatography. Fourier Transform Techniques. Gas Chromatography Mass Spectrometry Forensic Applications. Microscopy Appiications Forensic. X-Ray Absorption and Diffraction X-Ray Absorption X-Ray Diffraction - Powder. 

See also Atomic Absorption Spectrometry Principles and Instrumentation. Atomic Emission Spectrometry Inductively Coupled Plasma. Cosmetics and Toiletries. Derivatization of Analytes. Electrophoresis Is-otachophoresls. Environmental Analysis. Enzymes Overview. Extraction Supercritical Fluid Extraction Solid-Phase Extraction Solid-Phase Microextraction. Ion Exchange Ion Chromatography Applications. Liquid Chromatography Reversed Phase Liquid Chromatography-Mass Spectrometry. Nuclear Magnetic Resonance Spectroscopy - Applicable Elements Carbon-13 Phosphorus-31. Perfumes. 

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