Search results for "Spectrometry"
showing 10 items of 3206 documents
Optical saturation thermal lens spectrometry in non-polar solvents
1997
Abstract A model for thermal lens spectrometry (TLS) in partial optical saturation conditions which was previously applied to polar solutes in aqueous media is now checked with non-polar organic dyes and metal dithizonates in carbon tetrachloride. Some literature data are also examined. Most data can be consistently explained on the basis of the molecular structures, the sensitivity increasing with the capability of the solute to rapidly communicate the absorbed energy to the solvent molecules.
Applicability of hybrid linear ion trap-high resolution mass spectrometry and quadrupole-linear ion trap-mass spectrometry for mycotoxin analysis in …
2012
Abstract Recent developments in mass spectrometers have created a paradoxical situation; different mass spectrometers are available, each of them with their specific strengths and drawbacks. Hybrid instruments try to unify several advantages in one instrument. In this study two of wide-used hybrid instruments were compared: hybrid quadrupole-linear ion trap-mass spectrometry (QTRAP ® ) and the hybrid linear ion trap-high resolution mass spectrometry (LTQ-Orbitrap ® ). Both instruments were applied to detect the presence of 18 selected mycotoxins in baby food. Analytical parameters were validated according to 2002/657/CE. Limits of quantification (LOQs) obtained by QTRAP ® instrument ranged …
Ultra high performance liquid chromatography-time-of-flight high resolution mass spectrometry in the analysis of hexabromocyclododecane diastereomers…
2014
An efficient ultra high performance liquid chromatography (UHPLC)-time-of-flight high resolution mass spectrometry (TOF-HRMS) method was elaborated for the determination of hexabromocyclododecane (HBCD) diastereomers in fish samples and compared against UHPLC-Orbitrap-HRMS and UHPLC-triple quadrupole (QqQ) tandem MS (MS/MS) techniques. The TOF-HRMS analyzer was operated at high resolution (>10000 full width at half maximum (FWHM)) with scanning the m/z range from 600 to 700, to achieve picogram quantitation limits. The effects of various operational parameters on the instrumental response were systematically investigated. Evaluation of the influence of sample clean-up procedure steps on sig…
FT-ICR MS studies of ion-molecule reactions of Ru+ and Os+ with oxygen
2005
Abstract The reactions of stored ruthenium and osmium cations with oxygen have been studied in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. In case of osmium the reaction products OsO+ and OsO 2 + have been observed and corresponding reaction-rate constants have been determined. In addition, there is an unreactive fraction of Os+ ions due to the presence of a slightly endothermic reacting ground state. Only the excited states react with oxygen. For ruthenium no spontaneous reaction with oxygen has been observed unless the cyclotron motion of Ru+ was excited. The results are discussed with respect to a similar investigation in a Penning trap-TOF mass spectrometer […
Use of radiation sources with mercury isotopes for real-time highly sensitive and selective benzene determination in air and natural gas by different…
2015
A new analytical portable system is proposed for the direct determination of benzene vapor in the ambient air and natural gas, using differential absorption spectrometry with the direct Zeeman effect and innovative radiation sources: capillary mercury lamps with different isotopic compositions ((196)Hg, (198)Hg, (202)Hg, (204)Hg, and natural isotopic mixture). Resonance emission of mercury at a wavelength of 254 nm is used as probing radiation. The differential cross section of benzene absorption in dependence on wavelength is determined by scanning of magnetic field. It is found that the sensitivity of benzene detection is enhanced three times using lamp with the mercury isotope (204)Hg in…
Investigation on sol–gel synthesized Ag-doped TiO2 cermet thin films
2005
Abstract Undoped TiO 2 and Ag–TiO 2 (up to 23 at.% Ag) cermet thin films and polycrystalline powders have been prepared by sol–gel process. Their structure, composition, surface morphology and optical properties have been investigated by X-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS) and ultraviolet–visible spectroscopy (UV–VIS spectroscopy). It has been observed that while Ag does not form a solid solution with TiO 2 , it promotes the anatase to rutile phase transformation. The transformation temperature decreases from 827 °C for undoped TiO 2 to about 650 °C fo…
First isomeric yield ratio measurements by direct ion counting and implications for the angular momentum of the primary fission fragments
2018
We report the first experimental determination of independent isomeric yield ratios using direct ion counting with a Penning trap, which offered such a high resolution in mass that isomeric states could be separated. The measurements were performed at the Ion Guide Isotope Separator On-Line (IGISOL) facility at the University of Jyvaskyla. The isomer production ratios of Ge-81, Y-96,Y-97 Sn-128(,1)30, and Sb-129 in the 25-MeV proton-induced fission of U-na(t) and Th-232 were studied. Three isomeric pairs (Ge-81, Y-96, and Sb-129) were measured for the first time for the U-na(t)(p, f) reaction, while all the reported yield ratios for the Th-232(p, f) reaction were determined for the first ti…
Mycotoxin contamination in laboratory rat feeds and their implications in animal research
2016
Compound feed is particularly vulnerable to multi-mycotoxin contamination. A method for the determination of 12 mycotoxins; enniatins A, A1, B, B1; aflatoxins B1, B2, G1, G2; OTA; ZEA; T-2 and HT-2 by liquid chromatography-tandem mass spectrometry has been developed and applied for the analysis of laboratory rat commercial feeds. The method trueness was checked by recovery assays at three different spiked levels (n = 9). Recoveries ranged from 73% to 112%, and the intra-day and inter-day precision were lower than 9% and 13%, respectively. Limits of quantitation were lower than 15 μg/kg. Twenty-seven laboratory rats feed samples showed multi-contamination by at least three up to six differen…
Development and validation of a liquid chromatography tandem mass spectrometry method for the analysis of beta-agonists in animal feed and drinking w…
2010
A reproducible, sensitive and selective multiresidue analytical method for seven beta-agonists: clenbuterol (CBT), clenpenterol (CPT), ractopamine (RTP), brombuterol (BBT), mabuterol (MBT), mapenterol (MPT), and hydroxymethylclenbuterol (HMCBT) was developed and validated by using liquid chromatography tandem mass spectrometry (LC-MS/MS) in feed and drinking water samples. The validation was achieved according to the criteria laid down in the Commission Decision 2002/657/EC, however it was necessary to use minimum required performance limits (MRPLs) proposed by the Community Reference Laboratories (CRLs) due to the lack of maximum residue limits (MRLs) for beta-agonists. By setting up these…
A preliminary study in Wistar rats with enniatin : A contaminated feed
2014
A 28-day repeated dose preliminary assay, using enniatin A naturally contaminated feed through microbial fermentation by a Fusarium tricinctum strain, was carried out employing two months-old female Wistar rats as in vivo experimental model. In order to simulate a physiological test of a toxic compound naturally produced by fungi, five treated animals were fed during twenty-eight days with fermented feed. As control group, five rats were fed with standard feed. At the 28th day, blood samples were collected for biochemical analysis and the gastrointestinal tract, liver and kidneys were removed from each rat for enniatin A detection and quantitation. Digesta were collected from stomach, duode…