Diagnostic Fragment Ions (diagnostic + fragment_ion)

Distribution by Scientific Domains


Selected Abstracts


Simultaneous characterization of isoflavonoids and astragalosides in two Astragalus species by high-performance liquid chromatography coupled with atmospheric pressure chemical ionization tandem mass spectrometry

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 13 2007
Xi Zhang
Abstract A method was developed for the simultaneous identification of astragalosides (AGs) and isoflavonoids (IFs) in the roots of Astragalus membranaceus and Astragalus mongholicus by HPLC coupled with atmospheric pressure chemical ionization MS/MS (HPLC-APCI-MS/MS). Diagnostic fragment ions of AGs and different group of IFs were obtained with one AG and eight IF standards analyzed by CID-MS, which were adopted as characteristic MS/MS fingerprints for further identification of these compounds in the two Astragalus species by using HPLC-APCI-MS/MS. A total of 20 IFs and 10 AGs were identified or tentatively identified. Among them, six IFs were detected in A. membranaceus for the first time and five IFs were firstly identified in A. mongholicus. The results indicate that HPLC-APCI-MS/MS is a powerful tool for the simultaneous characterization of IFs and AGs in complex matrix. [source]


Gas chromatography/negative-ion chemical ionisation mass spectrometry for the quantitative analysis of morphine in human plasma using pentafluorobenzyl carbonate derivatives

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 7 2002
H. J. Leis
A sensitive and specific method for the quantitative determination of morphine in human plasma is presented. Morphine was extracted from plasma by solid phase extraction on C18 and converted to its pentafluorobenzyl carbonate trimethylsilyl derivative. The derivatives were analysed without further purification. Using gas chromatography/negative ion chemical ionisation mass spectrometry, a useful diagnostic fragment ion at m/z 356 is obtained at high relative abundance. Deuterated morphine was used as internal standard. Calibration graphs were linear within the range 1.25 to 320,nmol/L. Intra-day precision was 3.82% (15,nmol/L), 2.85% (75,nmol/L) and 4.13% (225,nmol/L), inter-day variability was found to be 1.77% (15,nmol/L), 4.95% (75,nmol/L) and 9.88% (225,nmol/L). Inter-day accuracy showed deviations of 2.18% (15,nmol/L), ,0.72% (75,nmol/L) and ,0.13% (225,nmol/L). The method is rugged and robust and has been applied to the batch analysis of morphine during pharmacokinetic profiling of the drug. Copyright © 2002 John Wiley & Sons, Ltd. [source]


Fiber introduction mass spectrometry: determination of pesticides in herbal infusions using a novel sol,gel PDMS/PVA fiber for solid-phase microextraction

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 6 2007
Rogério Cesar da Silva
Abstract An application of the direct coupling of solid-phase microextraction (SPME) with mass spectrometry (MS), a technique known as fiber introduction mass spectrometry (FIMS), is described to determine organochlorine (OCP) and organophosphorus (OPP) pesticides in herbal infusions of Passiflora L. A new fiber coated with a composite of poly(dimethylsiloxane) and poly(vinyl alcohol) (PDMS/PVA) was used. Sensitive, selective, simple and simultaneous quantification of several OCP and OPP was achieved by monitoring diagnostic fragment ions of m/z 266 (chlorothalonil), m/z 195 (,-endosulfan), m/z 278 (fenthion), m/z 263 (methyl parathion) and m/z 173 (malathion). Simple headspace SPME extraction (25 min) and fast FIMS detection (less than 40 s) of OCP and OPP from a highly complex herbal matrix provided good linearity with correlation coefficients of 0.991,0.999 for concentrations ranging from 10 to 140 ng ml,1 of each compound. Good accuracy (80 to 110%), precision (0.6,14.9%) and low limits of detection (0.3,3.9 ng ml,1) were also obtained. Even after 400 desorption cycles inside the ionization source of the mass spectrometer, no visible degradation of the novel PDMS/PVA fiber was detected, confirming its suitability for FIMS. Fast (ca 20 s) pesticide desorption occurs for the PDMS/PVA fiber owing to the small thickness of the film and its reduced water sorption. Copyright © 2007 John Wiley & Sons, Ltd. [source]


MS/MS profiling of taxoids from the needles of Taxus wallichiana,

PHYTOCHEMICAL ANALYSIS, Issue 1 2002
K. P. Madhusudanan
Abstract Ammonium cationisation has been used for taxoid profiling of partially purified methanolic extracts of needles of Taxus wallichiana growing in different regions of the Himalayas (Kashmir, Himachal Pradesh, UP Hills, Darjeeling, Sikkim and Arunachal Pradesh) by electrospray ionisation tandem mass spectrometry (MS/MS). The MS/MS spectra of the [M,+,NH4]+ or [M,+,H]+ ions gave structurally diagnostic fragment ions which revealed information about the taxane skeleton as well as the number and nature of the substituents. The rearranged 11(15,,,1)- abeo -taxanes showed a characteristic elimination of the hydroxyisopropyl group with an acetoxy/benzoyloxy group from C-9. The identification of the taxoids was achieved by comparison of the MS/MS spectra with those of authentic taxoids or was based on biogenetic grounds. The results were corroborated by liquid chromatography,MS analysis. Out of the 50 taxoids identified, 21 belonged to the rearranged class. The presence of paclitaxel in the samples from four regions was confirmed: the study also revealed the occurrence of several basic taxoids in these samples. ­MS/MS profiling by electrospray ionisation was shown to be a fast and reliable technique for the analysis of taxoid samples. Copyright © 2001 John Wiley & Sons, Ltd. [source]


Development of a method based on accelerated solvent extraction and liquid chromatography/mass spectrometry for determination of arylphenoxypropionic herbicides in soil

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 6 2001
Stefano Marchese
A sensitive and specific analytical procedure for determining arylphenoxypropionic herbicides in soil samples, using Ionspray ionization (ISI) liquid chromatography/mass spectrometry (LC/MS), is presented. Arylphenoxypropionic acids are a new class of herbicides used for selective removal of most grass species from any non-grass crop, commercialized as herbicide esters. Previous studies have shown that the esters undergo fast hydrolysis in the presence of vegetable tissues and soil bacteria, yelding the corresponding free acid. The feasibility of rapidly extracting arylphenoxypropionic herbicides from soil by accelerated solvent extraction (ASE) techniques was evaluated. Four different soil samples were fortified with target compounds at levels of 5 and 20,ng/g by following a procedure able to mimic weathered soils. Herbicides were extracted by a methanol/water (80:20 v/v) solution (0.12,M) of NaCl at 90,°C. After clean-up using graphitized carbon black (GCB) as absorbent, the extract was analyzed by HPLC/ISI-MS. The effect of concentration of acid in the mobile phase on the response of ISI-MS was investigated. The effects of varying the orifice plate voltage on the production of diagnostic fragment ions, and on the response of the MS detector, were also investigated. The ISI-MS response was linearly related to the amounts of analytes injected between 1 and 200,ng. The limit of detection (signal-to-noise ratio,=,3) of the method for the pesticides in soil samples was estimated to be less than 1,ng/g. Copyright © 2001 John Wiley & Sons, Ltd. [source]