Mass spectroscopy sample preparation

See also Biochemical Applications of Mass MS-MS and MS Organometallics Studied Using Spectrometry Fragmentation in Mass Spectrometry Mass Spectrometry Peptides and Proteins Studied Ion Energetics in Mass Spectrometry Ionization The- Using Mass Spectrometry Plasma Desorption loniza-ory IR Spectroscopy Sample Preparation Methods tion in Mass Spectrometry Spectroscopy of Ions. 

See also ATR and Reflectance IR Spectroscopy, Applications Biochemical Applications of Raman Spectroscopy Food Science, Applications of Mass Spectrometry Food Science, Appiications of NMR Spectroscopy Fourier Transformation and Sampiing Theory FT-Raman Spectroscopy, Appiications iR Spectrometers, IR Spectroscopy Sample Preparation Methods IR Spectroscopy, Theory IR Spectral Group Frequencies of Organic Compounds Nonlinear Optical Properties Raman Optical Activity, Spectrometers Raman Spectrometers. 

This chapter deals mainly with (multi)hyphenated techniques comprising wet sample preparation steps (e.g. SFE, SPE) and/or separation techniques (GC, SFC, HPLC, SEC, TLC, CE). Other hyphenated techniques involve thermal-spectroscopic and gas or heat extraction methods (TG, TD, HS, Py, LD, etc.). Also, spectroscopic couplings (e.g. LIBS-LIF) are of interest. Hyphenation of UV spectroscopy and mass spectrometry forms the family of laser mass-spectrometric (LAMS) methods, such as REMPI-ToFMS and MALDI-ToFMS. In REMPI-ToFMS the connecting element between UV spectroscopy and mass spectrometry is laser-induced REMPI ionisation. An intermediate state of the molecule of interest is selectively excited by absorption of a laser photon (the wavelength of a tuneable laser is set in resonance with the transition). The excited molecules are subsequently ionised by absorption of an additional laser photon. Therefore the ionisation selectivity is introduced by the resonance absorption of the first photon, i.e. by UV spectroscopy. However, conventional UV spectra of polyatomic molecules exhibit relatively broad and continuous spectral features, allowing only a medium selectivity. Supersonic jet cooling of the sample molecules (to 5-50 K) reduces the line width of their... 

Figure 5.3. TDS of solution-processed a-Si films. Three samples were prepared by the thermal decomposition of polysilane under the following conditions sample a, 300 °C for 10 min sample b, 300 °C for 120 min and sample c, 540 °C for 120 min. Desorbed gases from the samples were analyzed using mass spectroscopy while the samples were heated in a vacuum. [Reproduced with permission from Ref. 10. Copyright 2006 Nature Publishing Group.]...

Modern spectroscopy plays an important role in pharmaceutical analysis. Historically, spectroscopic techniques such as infrared (IR), nuclear magnetic resonance (NMR), and mass spectrometry (MS) were used primarily for characterization of drug substances and structure elucidation of synthetic impurities and degradation products. Because of the limitation in specificity (spectral and chemical interference) and sensitivity, spectroscopy alone has assumed a much less important role than chromatographic techniques in quantitative analytical applications. However, spectroscopy offers the significant advantages of simple sample preparation and expeditious operation. 

Rhenium(iii) Complexes.—A pure sample of [Re(acac)3] has been prepared by heating a mixture of [Na(acac)] and [ReCl2(acac)2], or [ReCl2(acac)PPh3] for 24h at 175°C in vacuo dark-red crystals formed just outside the hot zone [Re(hfac)3] has also been obtained pure, and the compounds were characterized by i.r., electronic, and mass spectroscopy, and respective magnetic moments of... 

The flameless atomic absorption method has a reproducibility of about 2% or better for homogeneous specimens. Checks (3) between AA and NAA (with radiochemical separation after irradiation) and isotope dilution spark source mass spectroscopy on thoroughly homogenized tuna fish and Bureau of Mines round-robin coal specimens indicate good agreement between the methods. (0.425 0.9%, 0.45 3.5%, and 0.45 4.4% for tuna by AA, NAA, and SSMS, respectively, and 1.004 is the average ratio of NAA to AA results for five coal samples.) The similar results indicate that the technique used in sample preparation... 

The reaction time was 3.5 hrs. The composition of the mixture of the reaction products determined by GLC was 65% ethylbenzene, 19.5% 3-phenylpropanal diethylacetal, and 10.5% ( —) (R)-2-phenylpropanal diethylacetal. The yield of hydroformylation products was 32%. The optically active acetal purified by preparative GLC (9) and identified by comparison of GLC and mass spectroscopy with a known sample had [< ]D25 —0.52° (neat). 

Hydroxy-4-methyl-4-penten-2-one (1) was prepared from 3-chloro-mesityl oxide using a modified procedure from the literature [ref.4], A reference sample of 4-methyl-4-penten-2,3-dione (2) was prepared from using the copper acetate method [ref.2], 4-methyl-pentan-2,3-dione (3) was purchased from Wiley Co. 2-Hydroxy-4-methyl-4-penten-3-one (4) was synthesized in 30% yield from 2-propenyl-magnesium bromide and 2-hydroxy-propionitrile in tetrahydrofurane. The structures of all compounds were confirmed by H-. C-NMR- and mass spectroscopy [ref. 5],... 

The compositions of the ceramic glazes were examined using laser-ablation inductively coupled-mass spectroscopy (LA-ICP-MS) at the University of Missouri Research Reactor (MURR). LA-ICP-MS is a surface analysis technique requiring little sample preparation. Because of its small spot size, areas of weathered glaze could be avoided during analysis (24). 

Wet chemical methods involve sophisticated sample preparation and standardization with National Bureau of Standards reference materials but are not difficult for the analytical chemist nor necessarily time consuming (Figure 1). The time from sample preparation to final results for various analytical methods, such as GFAA (graphite furnace atomic absorption), ICP (inductively coupled plasma spectroscopy), ICP-MS (ICP-mass spectrometry), and colorimetry, ranges from 0.5 to 5.0 h, depending on the technique used. Colorimetry is the method of choice because of its extreme accuracy. Typical results of the colorimetric analysis of doped oxides are shown in Tables I and II, which show the accuracy and precision of the measurements. 

The photocatalytic oxidation of alkylbenzenes and alkenylbenzenes has been widely reported. The data concerning alkylbenzenes have shown that the reactivity of toluenes is low when compared to other monosubstituted benzenes (Somarani et al., 1995). The effect of adding a zeolite, which is an acid solid catalyst, by Ti02/UV on various 4-substituted toluenes was studied by Somarani et al. (1995). The compounds of interest were prepared at 0.03 M in solutions containing TiOz. The effect of a zeolite was also studied by adding HY-type zeolites with various Si/Al ratios. The solutions were irradiated with a 125-W mercury lamp emitting light at 330 nm. Samples were taken at 48 hours and analyzed by GC/mass spectroscopy (MS) to determine percent conversions of the toluenes to the desired products. 

Chemical and instrumental (e.g., chromatography and mass spectrometry) methods have provided valuable information that lead to the advancement of cheese science. However, these techniques suffer from one or more of the following problems (1) the extensive use of solvents and gases that are expensive and hazardous, (2) high costs, (3) the requirement of specific accessories for different analytes, (4) the requirement of extensive sample preparation to obtain pure and clean samples, and (5) labor-intensive operation. These disadvantages have prompted for the evaluation and adoption of new, rapid, and simple methods such as Fourier-transform infrared (FTIR) spectroscopy. Many books are available on the basics of FTIR spectroscopy and its applications (Burns and Ciurczak, 2001 Sun, 2009). FTIR spectroscopy monitors the vibrations... 

The relative contribution of sample preparation depends on the steps in the measurement process. For instance, typically two-thirds of the time in an analytical chromatographic procedure is spent on sample preparation. An example of the determination of olanzapine in serum by high-performance liquid chromatography/mass spectroscopy (HPLC-MS) illustrates this point [3], Here, samples were mixed with an internal standard and cleaned up in a... 

Mass spectrometry (MS), infrared (IR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy with their numerous applications are the main instrumental techniques for the detection and identification of CWC-related chemicals. During the last few years, however, less laborious techniques such as liquid chromatography (LC) and capillary electrophoresis (CE) have become attractive for the analysis of water samples and extracts where sample preparation is either not required or is relatively simple. 

Heating and Mass Spectroscopy. Specimens were prepared as described above but using a Ni stub which had an attached thermocouple. The specimens were placed on a heatable sample mount in the preparation chamber and irradiated. The sample temperature was then raised at a rate of 20 C/min to 30 C/min from 100 C to 300 C. The RGA continuously recorded the spectral intensities at 19, 24, 31, 50, 69, 81,... 

The compounds are prepared by a metathesis reaction from the corresponding iodide or bromide salt. The compounds are typically low melting point salts (in many cases molten at room temperature), which range from being quite hydrophobic (TFSA, PF ) to completely water soluble and hygroscopic (DCA, BF4). The purity of the samples is established via solution NMR, electrospray mass spectroscopy, and chemical analytical analysis. 

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