Positive chemical ionization chromatography-mass

Bergh C, Torgrip R, Ostman C (2010) Simultaneous selective detection of organophosphate and phthalate esters using gas chromatography with positive ion chemical ionization tandem mass spectrometry and its application to indoor air and dust. Rapid Commun Mass Spectrom... 

The particle beam-liquid chromatography-mass spectrometry (PB-L0-M8) of phenols (phenol, 4-nitrophenol, and 1—naphthol) and their glucuronide and sulfate conjugates in electron impact (El) and positive chemical ionization (PCI) is described. 

Fig. 3. Plasma zl -tetrahydrocannabinol (THC), H-hydroxy-zl -tetrahydrocannabinol (11-OH-THC) and 11-nor-9-carboxy-zl -tetrahydrocannabinol (THCCOOH) concentrations in one participant over 24 h following administration of two 2.5-mgdronabinol(syntheticTHC) doses. Time zero is the time ofthefirst blood draw at 0730 hours. The 2.5-mg doses were administered with food at 1200 and 1800 (4.5 and 10.5 h after time zero). (Reprinted from Journal of Chromatography B, 789, Gustafson et al.. Validated method for the simultaneous determination of delta-9-tetrahydrocannabinol (THC), 1 Thydroxy-THC and 1 Tnor-9-carboxy-THC in human plasma using solid phase extraction and gas chromotography-mass spectrometry with positive chemical ionization, pp. 145, Fig. 2 therein. Copyright (2003) with permission from Elsevier)...

Gustafson RA, Moolchan ET, Barnes A, Levine B, Huestis MA (2003) Validated method for the simultaneous determination of delta-9-tetrahydrocannabinol (THC), 11-hydroxy-THC and 1 l-nor-9-carboxy-THC in human plasma using solid phase extraction and gas chromatography-mass spectrometry with positive chemical ionization. J Chromatogr B Analyt Technol Biomed Life Sci 798 145-154... 

Perr, J.M., et al. (2005) Gas chromatography positive chemical ionization and tandem mass spectrometry for the analysis of organic high explosives. Talanta, 67, 430 36. 

Campora P, Bermejo AM, TabtanCTo MJ, Fernandez P (2006) Use of gas chromatography/ mass spectrometry with positive chemical ionization for the determination of opiates in human oral fluid. Rapid Commun Mass Spectrom 20 1288-1292... 

A liquid chromatography-mass spectrometry (LC-MS) method that can quantitatively analyze urinar y normal and modified nucleosides in less than 30 min with a good resolution and sufficient sensitivity has been developed. Nineteen kinds of normal and modified nucleosides were determined in urine samples from 10 healthy persons and 18 breast cancer patients. Compounds were separ ated on a reverse phase Kromasil C18 column (2.1 mm I.D.) by isocratic elution mode using 20 mg/1 ammonium acetate - acetonitrile (97 3 % v/v) at 200 p.l/min. A higher sensitivity was obtained in positive atmospheric pressure chemical ionization mode APCI(-i-). 

Based on a new technology, particle beam enhanced liquid chromatography-mass spectrometry expands a chemist s ability to analyse a vast variety of substances. Electron impact spectra from the system are reproducible and can be searched against standard or custom libraries for positive compound identification. Chemical ionization spectra can also be produced. Simplicity is a key feature. A simple adjustment to the particle beam interface is all it takes. 

The lncos-50 is a relatively low-cost benchtop instrument as opposed to the research grade instruments discussed earlier. The gas chromatography-mass spectrometer transfer lines allow it to be used with either the Hewlett Packard 5890 or the Varian 3400 gas chromatographs. The Incos 50 provides data system control of the gas chromatography and accessories such as autosampler or liquid sample concentration. It can be used with capillary, wide-bore or packed columns. It performs electron ionization or chemical ionization with positive or negative detection. It also accepts desorption or other solids controls. 

Stan H-J, Kellner G. 1989. Confirmation of organophosphorus pesticide residues in food applying gas chromatography/mass spectrometry with chemical ionization and pulsed positive negative detection. Biomed and Environ Mass Spectrom 18(9) 645-651. 

Thanks to gas chromatography and atmospheric-pressure chemical-ionization mass-spectrometry analyses, a mechanism of nPr-BTP degradation has been proposed. The first step is assumed to be the attack at one CH2 group on the a position of the triazine rings to form a nitro compound observed by 15N NMR. In the second step, the compound is degraded into an alcohol (which is the main degradation product observed in the absence of acidic aqueous phase) or into a ketone (which is the main degradation product observed after the hydrolysis of nPr-BTP by molar nitric... 

S. Lacorte and D. Barcelo, Determination of parts per trillion levels of organophospho-rus pesticides in groundwater by automated on-line liquid-solid extraction followed by hquid chromatography/atmospheric pressure chemical ionization mass spectrometry using positive and negative ion modes of operation , Anal. Chem. 68 2464-2470 (1996). 

R.W. Read and R.M. Black, Rapid screening procedures for the hydrolysis products of chemical warfare agents using positive and negative ion liquid chromatography-mass spectrometry with atmospheric pressure chemical ionization, J. Chromatogr. A, 862, 169-177 (1999). 

Structural information about toxaphene components can be obtained by gas chromatography coupled to electron ionization mass spectrometry (GC/EI-MS), positive ion chemical ionization mass spectrometry (GC/PICI-MS) or negative ion chemical ionization MS(GC/NICI-MS). Mass separation is performed by low resolution quadrupole or high resolution magnetic field instruments, by ion trap systems (GC/IT-MS), or by tandem mass spectrometry (MS/MS) offering a broad spectrum of possibihties. 

A method that uses high performance liquid chromatography/ mass spectrometry (HPLC/MS) for the analysis of chlorinated phenoxyacid herbicides is described. During method development different techniques were used to increase both the sensitivity and the specificity of thermospray HPLC/MS for chlorinated acid herbicides. These included the operation of the instrument in the negative chemical ionization (NCI) mode initiated by discharge and the use of a wire-repeller in the ion source for efficient extraction of positive ions. Single quadrupole repeller-induced and multiple quadrupole collision activated dissociation (CAD) experiments were also performed to increase the structural information of the mass spectra. 

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