BACKGROUND High-performance liquid chromatography-tandem mass spectrometric (LC-MS/MS)1 analysis of plasma free metanephrines is the most diagnostically sensitive and specific screening test for the diagnosis of pheochromocytoma. We sought to develop an in-house method for this expensive test METHODS We used off-line isopropanol protein precipitation of plasma to remove interfering substances...

A polymeric microfluidic device for solid-phase extraction (SPE)-based isolation of nucleic acids is demonstrated. The plastic chip can function as a disposable sample preparation system for different biological and diagnostic applications. The chip was fabricated in a cyclic polyolefin by hot-embossing with a master mold. The solid phase consisted of a porous monolithic polymer column impregna...

A simple, semi-automated, microcolumn solid-phase extraction (SPE) system is optimized for the extraction, preconcentration and HPLC analysis of seven different explosives and explosive derivatives contaminating seawater, river water and well water samples. The microcolumns were constructed from 1/16 in. O.D. PTFE tubing (1 in.=2.54 cm) packed with 0.5-1.5 mg of SPE material. LiChrolut EN or Po...

Among the most important Relds in analytical chemistry are medical, food and environmental analysis, where the target analytes are often present at very low concentrations in rather complex matrices. Methods currently used for analysis, such as liquid chromatography, gas chromatography or capillary electrophoresis, must therefore be preceded by a selective isolation and concentration step. Comm...

Commercial solid-phase extraction columns packed with a stationary phase with bonded benzenesulfonic acid groups are readily converted to the silver ion form and can then be used for silver ion chromatography of lipids. To illustrate the utility of such procedures, methyl ester derivatives of fatty acids with zero to six double bonds were separated from each other by a simple stepwise elution s...

Solid-phase extraction methods are being used for increasing numbers of applications in lipid analysis, but especially as a rapid means of isolating particular components for further analysis. Many different types of packing material are available enabling most different modes of chromatography to be used, including adsorption, reversed-phase, silver-ion and ion-exchange. However, there are occ...

Consider how these problems could be solved by using a solid phase (such as a chromatographic sorbent) instead of the second liquid phase. There are still two distinct phases that can be readily segregated. Also, by proper selection of pH and type of solid phase sorbent, one could optimize the conditions to selectively partition the component(s) of interest on the solid phase. After removal of ...

reversed-phase (ISRP) material. Proteins do not adsorb on the hydrophilic exterior surfaces and do not penetrate into the hydrophobic interior surfaces, while analytes can reach the interior surfaces and be separated. (Reproduced with permission from Perry JA (1991) The internal surface reversed phase. Concept and applications. Journal of Liquid Chromatography 13: 1047}1074.) Gelfferich F (1962...

a novel magnetic mixed hemimicell solid phase extraction (mmhspe) technique for speciation analysis of soluble, ferrous and ferric iron in legumes sample by flame atomic absorption spectrometry analysis (faas) was developed. mmhspe system consisting of alumina-coated magnetite nanoparticles (fe3o4/al2o3nps) modified by sodium dodecylsulfate-1-(2-pyridylazo)-2-naphthol (sds-pan) have been succes...