Search results for "Spectroscopy"
showing 10 items of 10293 documents
Current trends in affinity-based monoliths in microextraction approaches: A review
2019
Abstract This article reviews the research contributions along the past five years concerning to monolithic materials for the development of affinity-based sorbents in the field of microextraction techniques. The first part of this paper includes an introduction regarding monolithic affinity media and information of different binding agents (such as immunoglobulin-binding proteins, enzymes, lectins, antibodies, aptamers, dyes and immobilized metal ions and nanoparticles, among others) that can act as affinity ligands. Then, the preparation of monoliths and ligand immobilization strategies as well as the different available formats (syringes, pipette tips, spin columns, capillaries, disks an…
Di-n-octyltin(IV) complexes with 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoic acid: Syntheses and assessment of solid state structures by 119Sn Mössb…
2007
Abstract Reactions of 5-[( E )-2-(aryl)-1-diazenyl]-2-hydroxybenzoic acids (LHH′, where the aryl group is an R-substituted phenyl ring such that for L 1 HH′: X = H; L 2 HH′: X=2′-OCH 3 ; L 3 HH′: X = 3′-CH 3 ; L 4 HH′: X = 4′-CH 3 ; L 5 HH′:X = 4′-Cl) with n Oct 2 SnO in 2:1 and 1:1 molar ratios have been investigated. Two types of complexes, n Oct 2 Sn(LH) 2 and {[ n Oct 2 Sn(LH)] 2 O} 2 , were isolated and they have been characterized by 1 H, 13 C, 119 Sn NMR, ESI-MS, IR and 119m Sn Mossbauer spectroscopic techniques in combination with elemental analyses. The crystal structures of n Oct 2 Sn(L 1 H) 2 ( 1 ), {[ n Oct 2 Sn(L 2 H)] 2 O} 2 ( 3 ) and {[ n Oct 2 Sn(L 3 H)] 2 O} 2 ( 4 ) were de…
Studies in organic mass spectrometry. Part 24† Electron ionization mass spectra of some aryl(2-nitrobenzo[b]thiophen-3-yl)amines
1999
The main fragmentation routes of eighteen title compounds and of three 5-chloro derivatives have been investigated with the aid of linked scan (B/E = constant) spectrometry, accurate mass measurements and deuterium labelling. Copyright © 1999 John Wiley & Sons, Ltd.
Synthesis and characterization of the first diorganotin(IV) complexes containing mixed arylazobenzoic acids and having skew trapezoidal bipyramidal g…
2005
Abstract Three diorganotin(IV) complexes of the type, [R 2 Sn(L a H)(L b H)] (R = n Bu or Me and, L a H and L b H are two different 5-[( E )-2-(aryl)-1-diazenyl]-2-hydroxybenzoate residues; a: aryl = 4′-Cl-(held constant) and b: aryl = 4′-Me or 4′-Br) have been prepared either by reacting n Bu 2 SnO, L a HH′ and L b HH′ (1:1:1) in anhydrous toluene or by reacting Me 2 SnCl 2 , L a HNa and L b HNa (1:1:1) in anhydrous methanol. The products were characterized by microanalysis, IR, NMR ( 1 H, 13 C, 119 Sn) and 119m Sn Mossbauer spectroscopy. A full characterization of the structures of the complexes [ n Bu 2 Sn(L a H)(L b H)] ( 1 and 2 ) and [Me 2 Sn(L a H)(L b H)] ( 3 ) in the solid state w…
The Ramsey method in high-precision mass spectrometry with Penning traps: Experimental results
2007
The highest precision in direct mass measurements is obtained with Penning trap mass spectrometry. Most experiments use the interconversion of the magnetron and cyclotron motional modes of the stored ion due to excitation by external radiofrequency-quadrupole fields. In this work a new excitation scheme, Ramsey's method of time-separated oscillatory fields, has been successfully tested. It has been shown to reduce significantly the uncertainty in the determination of the cyclotron frequency and thus of the ion mass of interest. The theoretical description of the ion motion excited with Ramsey's method in a Penning trap and subsequently the calculation of the resonance line shapes for differ…
Theoretical study of electronically excited cis- and trans-glyoxal
1997
Abstract The equation-of-motion coupled cluster method for excitation energies in the singles and doubles approximation (EOMEE-CCSD) is applied to an investigation of the structure and harmonic frequencies of planar conformers of glyoxal in their first excited singlet states. For the trans-isomer, agreement between calculated harmonic frequencies and observed fundamentals is generally satisfactory, although the theoretical values are slightly more than 10% too high for the carbonyl stretching modes. Parallel calculations of the corresponding ground state properties allow for an empirical prediction of the excited state frequencies in which calculated differences in normal-mode frequencies a…
Analytical Study of a Resinous Material Used as Sealing in Ancient Pottery Found in an Archaeological Site by Thermally Assisted Hydrolysis Methylati…
2009
Abstract A resin sample was found in the archaeological site of Lixus (Morocco), belonging to the second century BC. The resinous material was found inside an amphora containing iron remains used in the plug as sealing material to hermetically close the pottery. The resinous sample was studied by several analytical techniques, as thermally assisted hydrolysis and methylation–gas chromatography–mass spectrometry (THM–GC–MS), Fourier transformed infrared spectroscopy (FTIR), and light microscopy. The material was identified as a Pinaceae resin. Therefore, a modern pine resin was also analyzed to consider the influence of aging in the archaeological sample. The ancient material was found not t…
The Reduction Pathway of End-on Coordinated Dinitrogen. I. Vibrational Spectra of Mo/W−N2, −NNH, and −NNH2 Complexes and Quantum Chemistry Assisted N…
1999
Infrared and Raman spectra of [M(N(2))(2)(dppe)(2)] (M = W, Mo) and the two protonated derivatives [WF(NNH)(dppe)(2)] and [WF(NNH(2))(dppe)(2)](+) (dppe = 1,2-bis(diphenylphosphino)ethane) are presented. Using isotope substituted compounds ((15)N and D) the vibrations of the Y-M-N(2)H(x)() (x = 0, 1, 2; Y = N(2), F) central unit are identified, in particular the M-N and N-N stretching modes. In case of the monoprotonated systems, an equilibrium between metal- and nitrogen-protonated species exists that is clearly detectable in the IR spectra. Making use of theoretical force fields, a quantum chemistry assisted normal coordinate analysis (QCA-NCA) is performed for all three tungsten systems …
High resolution spectroscopy and potential determination of the (3)1Pi state of NaCs.
2006
The (3)(1)Pi state of the NaCs molecule was studied by high resolution Fourier-transform spectroscopy. The (3)(1)Pi--X (1)Sigma(+) laser induced fluorescence was excited by an Ar(+) ion laser or by a single-mode frequency-doubled cw Nd:YAG laser. The presence of argon buffer gas yielded rich rotational relaxation spectra allowing to enlarge the data set for the (3)(1)Pi state term values, as well as to observe Lambda splittings in a wide range of vibrational (v(')) and rotational (J(')) quantum numbers. The data field includes about 820 energy levels of (3)(1)Pi NaCs in the range from v(')=0 to 37 and from J(')=3 to 190, which corresponds to ca. 95% of the potential well depth. Direct fit o…
New Calibration Model: Combining Integrated Calibration Method and H-point Standard Addition Method to Detect and Avoid Interference Effects
2018
A new calibration methodology based on the combination of integrated calibration method (ICM) and the H-point standard addition method (HPSAM) is presented. It allows the diagnosis and correction o...