Search results for "Electrospray Ionization"
showing 10 items of 275 documents
Laser preparation of bunched ion beams
1997
Abstract Laser ionization at ISOLDE is performed with high repetition laser beams in the ion source unit and for daughter elements with low repetition lasers synchronized with laser desorption from a secondary target. We are preparing an implementation of thermal adsorption followed by laser desorption and laser ionization in the target ion source unit of ISOLDE. The combination of resonance ionization with thermal bunching allows the preparation of bunched and chemically pure ion beams. Bunched ion beams of Mg or Ca are prepared for post-acceleration at REX-ISOLDE. In order to investigate the process of adsorption and pulsed laser desorption, experiments are performed with Ba vapour. In a …
Assessment of Human Exposure to Deoxynivalenol, Ochratoxin A, Zearalenone and Their Metabolites Biomarker in Urine Samples Using LC-ESI-qTOF.
2021
Human are exposed to a wide range of mycotoxins through dietary food intake, including processed food. Even most of the mycotoxin exposure assessment studies are based on analysis of foodstuffs, and evaluation of dietary intake through food consumption patterns and human biomonitoring methods are rising as a reliable alternative to approach the individual exposures, overcoming the limitations of the indirect dietary assessment. In this study, human urine samples were analyzed, seeking the presence of deoxynivalenol (DON), ochratoxin A (OTA), zearalenone (ZEA), and their metabolites. For this purpose, 40 urine samples from female and male adult residents in the city of Valencia (Spain) were …
Application of hybrid linear ion trap-high resolution mass spectrometry to the analysis of mycotoxins in beer
2011
This paper reports the application of liquid chromatography electrospray ionization ion trap-orbitrap mass spectrometry for the determination of 18 mycotoxins (aflatoxins, fumonisins, trichothecenes, ochratoxin A, sterogmatocystin, beauvaricin, zearalenone and zearalenol) in beer. The extraction procedure was carried out by solid phase extraction (SPE): SPE columns were conditioned with acetonitrile/methanol and water. Beer was loaded onto the column which was washed with water. In these conditions, the recoveries were more than 65% and the relative standard deviation (RSD) were below 18%. The lowest limits of quantification (LLOQ) ranged from 9 to 155 ng ml(-1). Matrix-matched calibration …
Occurrence of Free and Conjugated Mycotoxins in Aromatic and Medicinal Plants and Dietary Exposure Assessment in the Moroccan Population.
2021
Aromatic and medicinal plants (AMPs), as herbal material, are subjected to contamination by various mycotoxin-producing fungi, either free and conjugated. Such a problem is associated with poor storage practices, and lack of adopting good agricultural practices and good harvesting practices. Nevertheless, AMPs are poorly investigated. The purpose of this study was to investigate the co-occurrence of 15 mycotoxins (four aflatoxins (AFB1, AFB2, AFG1, and AFG2), ochratoxin A (OTA), beauvericin (BEA), four enniatins (ENA, ENA1, ENB, and ENB1), zearalenone (ZEN), alternariol (AOH), tentoxin (TENT), T-2, and HT-2 toxins) in 40 samples of AMPs frequently consumed in Morocco by using liquid chromat…
Levels of ochratoxin A in wheat and maize bread from the central zone of Portugal.
2007
Ochratoxigenic fungi are natural contaminants of cereal and the produced toxins are harmful to humans and animals. Ochratoxin A (OTA) is among the most important mycotoxins, and the International Agency for Research on Cancer (IARC) classifies it as possibly carcinogenic to humans (group 2B). A total of 61 samples of bread from the central zone of Portugal were analysed for OTA by liquid chromatography (LC) with fluorescence detection (FD). For confirmation two procedures were applied, methyl ester derivatization with boron trifluoride-methanol and liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI/MS/MS). As far as we know, this is the first report where on-line…
Analytical utility of quadrupole time-of-flight mass spectrometry for the determination of pesticide residues in comparison with an optimized column …
2009
Abstract A multiresidue method for the analysis of 30 pesticides with different physicochemical properties in fruits and vegetables was developed. The method involves a rapid and small-scale extraction procedure based on matrix solid-phase dispersion using octadecylsilyl (C18) as the dispersant and dichloromethane as the eluent. The target pesticides were determined using column high-performance liquid chromatography/triple quadrupole-tandem mass spectrometry (LC/QqQ-MS/MS). The method was validated for sensitivity, linearity, reproducibility, and accuracy. A recovery study was conducted at 3 different levels, and the average ranged from 74 to 99 for all of the studied compounds, with relat…
Electrochemical and spectroscopic investigations of selected N -heteroalkylaminomethylenebisphosphonic acids with Pb(II) ions
2016
Abstract The coordination properties of aminomethylenebisphosphonic acids towards various metal ions have been exploited during the last decade. These compounds are good chelators for biologically important metal ions, such as Cu(II), Fe(II), Zn(II), Ca(II), and Mg(II), as well as a toxic ion (i.e., Cd(II)). In this study, the interactions of five aminomethylenebisphosphonates with N-substituted heteroalkyl moieties (L1, L2 and L3) and their N-pyridyl (L4) and N-benzylpiperazine (L5) derivatives with Pb(II) ions were investigated. A wide range of analytical methods were employed, including potentiometry, pulse polarography (DPP), nuclear magnetic resonance (NMR) spectroscopy and electrospra…
Interactions of N-heteroalkylaminomethylenebisphosphonic acids with Cd(II) ions: Electrochemical and spectroscopic investigations
2015
The aminomethylenebisphosphonates are known to be excellent chelators for many metal ions. In this work, the coordination properties of three different aminomethylenebisphosphonates with N-substituted heteroalkyl moieties (L1, L2 and L3) and their N-pyridyl derivative (L4) toward cadmium(II) ions are described. Due to their coordination abilities over a broad range of pH, the compounds of this group are good candidates for heavy metal detoxification. To determine the stability constants and the coordination mode of formed aminomethylenebisphosphonate-cadmium(II) complexes, four analytical methods were employed: potentiometry, pulse polarography (DPP), nuclear magnetic resonance spectroscopy…
The Formation of Glycerol Oligomers with Two New Types of End Groups in the Presence of a Homogeneous Alkaline Catalyst
2019
The purpose of this work was to synthesize and characterize oligoglycerols with the chains of more than four repeating units. Those oligoglycerols may have some interesting applications, among others, as polyoxyalkylation starters. The glycerol oligomerization process was carried out during 12 h, at 230 °
PLA2-mediated catalytic activation of its inhibitor 25-acetyl-petrosaspongiolide M: serendipitous identification of a new PLA2 suicide inhibitor.
2004
Abstract25-Acetyl-petrosaspongiolide M (PMAc) (1), a mild non-covalent PLA2 inhibitor, unexpectedly recovers, after incubation with bvPLA2, the ability to covalently modify the enzyme target. This study demonstrates the catalytic effect of bvPLA2 in converting 1 in its deacetylated congener petrosaspongiolide M (PM) (2), a strong covalent PLA2 inhibitor whose molecular mechanism of inhibition has already been clarified. Moreover, our findings outline the potential role of PMAc as anti-inflammatory pro-drug, by virtue of its ability of delivering the active PM agent at the site of inflammation, functioning as a suicide inhibitor.