Search results for "Spectrometry"
showing 10 items of 3206 documents
Mineral Profile
2013
The identification of foods with protected designation of origin (PDO) has been a long-standing issue. Its detection provides valuable information to regulatory commissions (government and industries) which can regulate precise quality control procedures for their products. Authentication of food covers many different aspects, including characterization, mislabelling and misinformation regarding origin, and adulteration, which is defined as the process to reduce the quality or nature of a given substance by adding a foreign or an inferior substance and removing a vital element. Numerous methods have been developed as fingerprinting methodologies for PDO products. The analytical techniques c…
Local electrochemical impedance measurements on inclusion-containing stainless steels using microcapillary-based techniques
2009
MnS inclusions are good precursor sites for pitting corrosion of stainless steel. The objective of this paper was to quantify the passive properties of resulfurized stainless steel after immersion in chloride media. This was done by combining microcapillary techniques with electrochemical impedance spectroscopy and numerical analysis (specific equivalent circuit). It was shown that sulfur species produced in the electrolyte during the dissolution of inclusions react with the native passive film to CrS and FeSO 4 . Local electrochemical impedance spectroscopy measurements provided data describing the behaviour of the affected matrix at the microscale. For example, the value of the charge tra…
The Measurement of the CO2 Hb Binding Curve of Human Hemoglobin by 13C-NMR Spectrometry
1980
It is well known that under physiological conditions CO2 binds to the four terminal amino groups of hemoglobin (Hb) (Kilmartin and Rossi-Bernardi, 1971). The carbamino compounds which are formed by this reaction are involved in the Haldane effect.
Test of multielement analysis of bone samples using instrumental neutron activation analysis (INAA) and anti-Compton spectrometry
1997
INAA and anti-Compton spectrometry has been employed in the analysis of test bone samples. Validity and accuracy of the method were checked by the use of two biological reference materials procured from the National Institute of Standards and Technology, USA (NIST) and the International Atomic Energy Agency, Austria (IAEA). NIST 1486 Bone Meal (ca. 200–800 mg) and A-11 Milk Powder (ca. 200–600 mg) samples were irradiated in the 100 kW TRIGA Mainz reactor. Concentrations of 13 elements in both biological reference materials have been determined and were found in good agreement with the certified and provisional values.
On-line vapor-phase generation combined with Fourier transform infrared spectrometry
2008
We present a critical review of on-line vapor-phase generation combined with Fourier transform infrared spectrometry for detection. We discuss different experimental approaches developed for generating the vapor phase based on different principles (e.g., thermal volatilization, acid-base, redox reaction and covalent hydride generation). Using examples of applications, we try to demonstrate the analytical potential of on-line vapor-phase generation in vibrational spectrometry in order to improve the selectivity and the sensitivity of the measurement step and to make environmentally-friendly procedures available for problem solving in the analytical laboratory. We pay special attention to int…
Binding Modes of Nonspherical Anions to N-Alkylammonium Resorcinarenes in the Solid State
2012
A series of hydrogen bond stabilized N-alkylammonium resorcinarene salts with nitrate, triflate, and picrate as the counteranions were synthesized and characterized with 1H NMR and electrospray ionization (ESI) mass spectrometry. Together with electrostatic interactions, the binding of the anions with several hydrogen bond donor sites proceeds through a complex array of intra- and intermolecular hydrogen bonds, evidenced by single crystal X-ray diffraction analysis. These N-alkyl ammonium resorcinarenes bind the larger nonspherical anions into deformed cavitand-like structures and enforce a transformation of the resorcinarene conformation from almost symmetrical to extremely distorted.
Comparison of hard vaporization and soft ionization techniques in the mass spectrometry of some palladium(II) and platinum(II) complexes with C-bonde…
1990
Abstract Electron impact, fast atom bombardment and laser induced vaporization techniques are compared in the mass spectrometric behaviour of some palladium(II) and platinum(II) complexes with C-bonded heterocyclic ligands of the type trans -[MCl(R N )(PPh 3 ) 2 ] [M = Pd, R N = 2-pyridyl, 1 ; 2-pyrazyl, 2; 2-pyrimidyl, 3; M = Pt, R N = 2-pyridyl, 4 ].
Sicilian bottled natural waters: Major and trace inorganic components
2013
Sixteen bottled waters of various Sicilian brands, 11 natural mineral waters and five normal drinking waters, were analyzed for major and trace inorganic components by ion chromatography (IC) and inductively coupled plasma-mass spectrometry (ICP-MS), respectively. The bottled waters represent a variety of water types with significantly different compositions in terms of salinity, major components and trace elements. Chemically, they range from Ca–HCO3 and Ca–SO4 to Na–HCO3 types. Total dissolved solids ranges from 54 to 433 mg/L, total hardness from 25 to 238 mg/L CaCO3, and measured Na content from 5.7 to 57 mg/L. According to total dissolved ions, all the bottled waters were classified as…
Detection of security relevant substances within the cooperative project SAFE XUV
2008
The objective of this project funded by the German BMBF was to show that security relevant substances can be detected in complex matrices at low concentrations using single photon ionization ion trap mass spectrometry (SPI-ITMS). The advantage of such a soft ionization technique is a reduction of unwanted fragment ions in mass spectra allowing identification of signals from complex matrices and enabling MS/MS capability. The MS/MS studies permit low false-positive and false-negative rates. Additionally, the accumulation of the ions in the ion trap decreases the detection limit. To obtain low detection limits the ionization potentials (IPs) of the relevant substances have to be below the IPs…
Electrodes for REMPI spectroscopy in static gases and calculation of REMPI intensities: Application to molecular oxygen
1994
Resonance-enhanced multiphoton ionization (REMPI) of 16 O 2 X 3 Σ g − (ν = 0) through (3sσ g ) d'Π g (ν = 0) by using (2 + 1) one-colour photons is reported. This REMPI process, already observed and analysed by other authors at low pressure and low rotational temperature with mass spectrometry detection, is used to test our first detector of ionizations. Experimental difficulties have led to the design of an original arrangement of electrodes to collect electrons at room temperature and 1 Torr pressure of static molecular oxygen. A calculated spectrum is compared with the observed REMPI spectrum. The calculation uses the polarizability tensor and takes into account the competition between i…