Search results for "MASS SPECTROMETRY"
showing 10 items of 2544 documents
Determination of bisphenol diglycidyl ether residues in canned foods by pressurized liquid extraction and liquid chromatography–tandem mass spectrome…
2005
Abstract A new confirmatory method for simultaneous determination of bisphenol diglycidyl ether residues (BADGE, BADGE·H2O, BADGE·2H2O, BADGE·H2O·HCl, BADGE·HCl, BADGE·2HCl, BFDGE and BFDGE·2HCl) from canned food has been developed. The proposed method includes extraction by pressurized liquid extraction (PLE) followed by liquid–liquid partition and purification by solid phase extraction (SPE). Several solvent systems and different operating conditions (time, temperature) have been investigated for PLE optimization. A reversed-phase high-performance liquid chromatography (RP-HPLC) coupled to atmospheric pressure chemical ionisation tandem mass spectrometry (APCI-MS–MS) method was developed …
Making Broad Proteome Protein Measurements in 1−5 min Using High-Speed RPLC Separations and High-Accuracy Mass Measurements
2005
The throughput of proteomics measurements that provide broad protein coverage is limited by the quality and speed of both the separations as well as the subsequent mass spectrometric analysis; at present, analysis times can range anywhere from hours (high throughput) to days or longer (low throughput). We have explored the basis for proteomics analyses conducted on the order of minutes using high-speed capillary RPLC combined through on-line electrospray ionization interface with high-accuracy mass spectrometry (MS) measurements. Short 0.8-microm porous C18 particle-packed 50-microm-i.d. capillaries were used to speed the RPLC separations while still providing high-quality separations. Both…
Comparison of solid-phase microextraction and stir bar sorptive extraction for determining six organophosphorus insecticides in honey by liquid chrom…
2004
Abstract Two approaches based on sorptive extraction, solid-phase microextraction (SPME) and stir bar sorptive extraction (SBSE), in combination with liquid chromatography (LC)–atmospheric pressure chemical ionization mass spectrometry (MS) have been assayed for analyzing chlorpyriphos methyl, diazinon, fonofos, phenthoate, phosalone, and pirimiphos ethyl in honey. In both, SPME and SBSE, enrichment was performed using a poly(dimethylsiloxane) coating. Significant parameters affecting sorption process such as sample volume, sorption and desorption times, ionic strength, elution solvent, and dilution (water/honey) proportion were optimized and discussed. Performance of both methods has been …
Determination of a three-step excitation and ionization scheme for resonance ionization and ultratrace analysis of Np-237
2011
Abstract The long-lived radio isotope 237 Np is generated within the nuclear fuel cycle and represents a major hazard in the final disposal of nuclear waste. Related geochemical research requires sensitive methods for the detection of ultratrace amounts of neptunium in environmental samples. Resonance ionization mass spectrometry (RIMS) has proven to be one of the most sensitive methods for the detection of plutonium. A precondition for the application of RIMS to ultratrace analysis of neptunium is the knowledge of an efficient and selective scheme for optical excitation and ionization. Therefore, a multitude of medium to high-lying atomic levels in neptunium was located by applying in-sour…
Pesticide residue determination in fruit and vegetables by liquid chromatography–mass spectrometry
2000
An overview is given of pesticide residue determination in fruit and vegetables by liquid chromatography-mass spectrometry (LC-MS). Emphasis is placed on the thermospray, particle beam and atmospheric pressure ionization interfaces including advantages and drawbacks and typical detection limits. The capacity of each interface to provide useful data for identification/confirmation of analytes and the possibility of obtaining structural information for the identification of target and non-target compounds is discussed. Finally, sample preparation techniques are dealt with in relation to their influence on further LC-MS determination.
Understanding retention and metabolization of aroma compounds using an in vitro model of oral mucosa.
2020
International audience; The mechanism leading to aroma persistence during eating is not fully described. This study aims at better understanding the role of the oral mucosa in this phenomenon. Release of 14 volatile compounds from different chemical classes was studied after exposure to in vitro models of oral mucosa, at equilibrium by Gas-Chromatography-Flame Ionization Detection (GC-FID) and in dynamic conditions by Proton Transfer Reaction- Mass Spectrometry (PTR-MS). Measurements at equilibrium showed that mucosal hydration reduced the release of only two compounds, pentan-2-one and linalool (p < 0.05), and suggested that cells could metabolize aroma compounds from different chemical fa…
IsoSpec2: ultrafast fine structure calculator
2020
Abstract: High-resolution mass spectrometry becomes increasingly available with its ability to resolve the fine isotopic structure of measured analytes. It allows for high-sensitivity spectral deconvolution, leading to less false-positive identifications. Analytes can be identified by comparing their theoretical isotopic signal with the observed peaks. Necessary calculations are, however, computationally demanding and lead to long processing times. For wheat (trictum oestivum) alone, Uniprot holds more than 142 000 candidate protein sequences. This is doubled upon sequence reversal for identification FDR estimation and further multiplied by performing in silico digestion into peptides. The …
Recent developments in resonance ionization mass spectrometry for ultra-trace analysis of actinide elements
2019
Abstract Resonance ionization mass spectrometry is an efficient tool to detect minute amounts of long-lived radio-isotopes in environmental samples. Applying resonant excitation and ionization with pulsed laser radiation within a hot cavity atomizer enables the sensitive detection and precise quantification of long-lived actinide isotopes. Due to the inherently element selective ionization process, this method ensures ultimate suppression of contaminations from other elements and molecules. The characterization of in-source resonance ionization of the actinide elements U, Th, Np, and Am using a compact quadrupole mass spectrometer (QMS) setup are discussed.
Quantitative phase analysis and thickness measurement of surface-oxide layers in metal and alloy powders by the chemical-granular method
1998
The principles of the chemical-granular analysis of metal and alloy powders are reviewed and the results are compared with those provided by the spectroscopic analytical techniques XPS, AES and SIMS, including ion etching in their depth-profiling mode, when they are applied to the same materials. Several examples are analysed and it is shown that the chemical-granular method alone can provide the very same information as depth profiling. However, it is averaged over a macroscopic powder sample in contrast to one or a few single particles. Nevertheless, it is the combination of the chemical-granular and depth-profiling analyses that really provides an unparalleled description in quantitative…
Laser cleaning of oxide iron layer : efficiency enhancement due to electrochemical induced absorptivity change
1999
Laser cleaning experiments exhibited a higher cleaning efficiency of the laser cleaning upon application of electrochemical potential on an oxidised iron surface. The objective of this study is to clarify the role of such an electrochemical control on cleaning efficiency. Therefore a study by optical spectrometry at normal incidence in the relevant conditions was performed. From these measurements the optical parameters n and k were deduced. While n is mainly not affected, k changes for a factor of 10 upon application of an electrochemical potential. These results explain the differences in laser cleaning efficiency due to the modified absorption length.