High performance liquid electron ionization/chemical

ECD = electron capture detector GC = gas chromatography HPLC = high-performance liquid chromatography MC = microcoulometric detector MS = mass spectrometry NICI = negative ion chemical ionization RSD = relative standard deviation SPE = solid phase extraction... 

Figure 2.1 Mass spectrometric approach. Dl, direct inlet GC, gas chromatography HPLC, high performance liquid chromatography CZE, capillary zone electrophoresis El, electron ionization Cl, chemical ionization ESI, electrospray ionization DESI, desorption electrospray ionization APCI, atmospheric pressure chemical ionization MALDI, matrix assisted laser desorption ionization B, magnetic analyzer E, electrostatic analyzer...

Note. Abbreviations g.l.c., gas-liquid chromatography e.i.-m.s., electron-impact mass spectrometry c.i.-m.s., chemical-ionization mass spectrometry h.p.l.c., high-performance liquid chromatography h.p.a.e., high pH anion-exchange f.a.b.-m.s., fast-atom-bombardment mass spectrometry l.s.i.-m.s., liquid secondary-ion mass spectrometry n.O.e., nuclear Overhauser enhancement. Details of these methodologies are given in Ref. (3). 

Strege summarized the technique of high-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS) in dereplication of natural products. In contrast to earlier electron impact ionization (El), ESI technique is applicable to virtually any ion in solution with a soft ionization process. A comparison of ESI with fast atom bombardment (FAB), matrix assisted laser desorption ionization (MALDI), atmospheric pressure chemical ionization (APCI) and other techniques demonstrates its superior sensitivity, compatibility and reliability when coupled with HPLC [51]. 

Many approaches have been used to form ions, both in high-vacuum and near-atmospheric pressure conditions. Electron ionization (El) and chemical ionization (Cl) are ionization techniques used when gas phase molecules can be introduced directly into the analyzer from a gas chromatograph. In other analyses, such as high-performance liquid chromatography-mass spectrometry (HPLC-MS),... 

Abbreviations APCI Atmospheric Pressure Chemical Ionization DAG Diacyl-glycerols DE Delayed Extraction DHB 2,5-Dihydroxybenzoic Acid El Electron Impact ESI Electrospray Ionisation FACS Fluorescence-activated cell sorting GC Gas Chromatography HDL High Density Lipoprotein HPLC High-Performance Liquid Chromatography IR Infrared LDL Low Density Lipoprotein LOD Level of Detection LOQ Level of Quantification LPC Lyso-Phosphatidylcholine LPL Lyso-Phospholipid MALDI Matrix-... 

Chemical analysis of hazardous substances in air, water, soil, sediment, or solid waste can best be performed by instrumental techniques involving gas chromatography (GC), high-performance liquid chromatography (HPLC), GC/mass spectrometry (MS), Fourier transform infrared spectroscopy (FTIR), and atomic absorption spectrophotometry (AA) (for the metals). GC techniques using a flame ionization detector (FID) or electron-capture detector (BCD) are widely used. Other detectors can be used for specific analyses. However, for unknown substances, identification by GC is extremely difficult. The number of pollutants listed by the U.S. Environmental Protection Agency (EPA) are only in the hundreds — in comparison with the thousands of harmful... 

A high-performance liquid chromatographic/atmospheric pressure chemical ionization-mass spectrometric (HPLC/APCI-MS) method has been developed for the determination of the pesticide clofentezine (3,6-bis(2-chlorophenyl)-l,2,4.5-tetrazine) in plum-, strawberry-, and blackcurrant-based fruit drinks <1995RCM1441>. The structural characterization and the mass spectrometric behavior of pyridazinofurocoumarins, prepared by the inverse electron demand Diels-Alder reaction between furocoumarinones and 3,6-bis(methoxycarbonyl)-l,2,4,5-tetrazine, were studied under electron ionization conditions via sequential product ion fragmentation experiments <2004RCM564>. 

GC-gas chromatography, HPLC-high performance liquid chromatography, SFC-supercritical fluid chromatography, TLC-thin layer chromatography, MS-mass spectrometry, MF-mass fragmentography, Cl-chemical ionization, El-electron ionization, ECI-electron capture ionization, IS-ionspray, FAB-fast atom bombardment, ESI-electrospray, SIMS-secondary ion mass spectrometry. 

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