Fast atom bombardment mass spectroscopy FAB-MS

The average DS as determined by these methods provides only the simplest characterization of these derivatives, and further analysis was necessary to characterize the mixture of SBE bands of different levels of substitution. Due to the presence of the anionic sulfonate substituent, it is possible to use capillary electrophoresis (23), to separate the SBE-CD substitution bands and to characterize the fingerprint of the composition (Fig. 10). Anion exchange chromatography (24) was utilized to isolate separate substitution bands (mono- to deca-derivatives) that were subsequently identified by NMR and fast atom bombardment mass spectroscopy (FAB-MS). 

From a practical perspective the chlorozincate liquids are easier to make and handle than the corresponding chloroaluminates as they are less susceptible to hydrolysis. As with the aluminum-based liquids the electrochemistry is dominated by the complex anions present in the liquid, which depend upon the composition and the relative Lewis acidity. There is some evidence, however, that hydrolysis of zinc Lewis basic melts does occur as Hsiu et al. used fast atom bombardment mass spectroscopy (FAB MS) to show that some zinc species do contain oxygen [105]. 

We reported that Hm transformants of A. chrysogenum expressing only the DAO gene, as well as some transformants of pHDVll having DAO and weak acylase activities, prO duced GL 7 ACA and GL 7-ADACA (6,7). However, those products were detected as products of different retention times compared with those of standard samples under a newly developed analysis condition of HPLC. Those products were isolated and ana-lyzed by fast atom bombardment mass spectroscopy (FAB-MS). Additionally, the a-hydroxyadipyl side chains of those products were analyzed by an isomer... 

Lattimer and co-workers [30] have applied mass spectroscopy to the determination of antioxidants and antiozonants in rubber vulcanisates. Direct thermal desorption was used with three different ionisation methods (electron impact, Cl, field ionisation (FI)). The vulcanisates were also examined by direct fast atom bombardment mass spectroscopy (FAB-MS) as a means for surface desorption/ionisation. Rubber extracts were examined directly by these four ionisation methods. Of the various vaporisation/ ionisation methods, it appears that FI is the most efficient for identifying organic additives in the rubber vulcanisates. 

Figure 5.9 Fast atom bombardment - mass spectroscopy (FAB-MS) of cyclic PBT oligomers from a solution ring-chain reaction in 1,2-dichlorobenzene, (CO.CgH. CO.O) ). ), where x = 2-6. Reproduced with permission from J.J.L. Bryant...

Several physical methods have been employed to ascertain the existence and nature of ICs infrared (IR) absorption spectroscopy nuclear magnetic resonance (NMR) spectroscopy,14 including JH nuclear Overhauser effect (NOE) difference spectroscopy, H 2-D rotating-frame Overhauser effect spectroscopy (2-D ROESY),15 and solid-state 13C cross-polarization/magic angle spinning (CP/MAS) spectroscopy 16 induced circular dichroism (ICD) absorption spectroscopy 17 powder and singlecrystal X-ray diffraction 18 and fast atom bombardment mass spectrometry (FAB MS). 

Nogami s group (Tsuda et al., 1993) showed that dichlorocarbene, generated by pyrolysis of sodium trichloroacetate in a mixture of benzene and 1,2-dimethoxy-ethane, reacts with C o to give the [6,6]-closed methanofullerene, as shown by negative ion fast atom bombardment mass spectrometry (FAB MS) and by NMR spectroscopy. 

HPLC methods previously described (22.24.26.42). The cinnamoyl ester-bearing compounds were detected by uitraviolet (UV) monitoring at 280 nm. Structure elucidation of the purified compounds was carried out by means of infrared (iR) and UV spectrophotometry, proton and carbon-13 nuciear magnetic resonance (NMR) spectroscopy, and electron impact (EI-) and fast-atom bombardment mass spectrometry (FAB-MS). The structures of the two new isolates and three of their derivatives were established on the basis of spectroscopic data and spectrai evidence obtained on comparison with azadirachtin (23). 

BASIL CIS CV CVD DSSC ECALE EC-STM EDX, EDS, EDAX EIS EMF EQCM FAB MS FFG-NMR Biphasic Acid Scavenging Utilizing Ionic Liquids Copper-indium-selenide Cyclic Voltammetry Chemical Vapor Deposition Dye Sensitized Solar Cell Electrochemical Atomic Layer Epitaxy Electrochemical in situ scanning tunnelling microscopy Energy Dispersive X-ray analysis Electrochemical Impedance Spectroscopy Electromotive Force Electrochemical Quarz Crystal Microbalance Fast atom bombardment mass spectroscopy Fixed Field Gradient Nuclear Magnetic Resonance... 

The structures of vanicosides A (1) and B (2) and hydropiperoside (3) were established primarily by one- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy techniques and fast atom bombardment (FAB) mass spectrometry (MS).22 The presence of two different types of phenylpropanoid esters in 1 and 2 was established first through the proton (4H) NMR spectra which showed resonances for two different aromatic substitution patterns in the spectrum of each compound. Integration of the aromatic region defined these as three symmetrically substituted phenyl rings, due to three p-coumaryl moieties, and one 1,3,4-trisubstituted phenyl ring, due to a feruloyl ester. The presence of a sucrose backbone was established by two series of coupled protons between 3.2 and 5.7 ppm in the HNMR spectra, particularly the characteristic C-l (anomeric) and C-3 proton doublets... 

Dendrimer characterization was accomplished by 13C, NMR and FT-IR spectroscopy as well as mass spectrometry using fast atom bombardment (FAB) and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) techniques. Molecular ion base peaks were observed in the MALDI-TOF MS of polyester 168 (mlz 18900 (calcd. 19044)) along with minor peaks at 37000 and 54000 mlz corresponding to ionic gasphase dimer and trimer complexes. 

Mass spectroscopy [electron ionisation (El), chemical ionisation (Cl), electrospray ionisation (ESI), fast atom bombardment (FAB), matrix-associated laser desorption ionisation (MALDI), inductively coupled plasma-mass spectrmetry (ICP-MS, cf and ), etc]... 

Hyphenated TLC techniques. TLC has been coupled with other instrumental techniques to aid in the detection, qualitative identification and, occasionally, quantitation of separated samples, and these include the coupling of TLC with high-pressure liquid chromatography (HPLC/TLC), with Fourier transform infra-red (TLC/FTIR), with mass spectrometry (TLC/ MS), with nuclear magnetic resonance (TLC/NMR) and with Raman spectroscopy (TLC/RS). These techniques have been extensively reviewed by Busch (1996) and by Somsen, Morden and Wilson (1995). The chemistry of oils and fats and their TLC separation has been so well established that they seldom necessitate the use of these coupling techniques for their identification, although these techniques have been used for phospholipid detection. Kushi and Handa (1985) have used TLC in combination with secondary ion mass spectrometry for the analysis of lipids. Fast atom bombardment (FAB) has been used to detect the molecular species of phosphatidylcholine on silica based on the molecular ion obtained by mass spectrometry (Busch et al, 1990). 

It was not possible to use MS for the characterization and identification of chlorophylls and its derivatives until the development of desorption methods (desorption ionization) appropriate for nonvolatile and thermolabile compounds. The mass spectmm of chlorophylls has been obtained using laser desorption [92-94], field desorption [95], plasma desorption [96,97], fast atom bombardment (FAB) [28, 98-101], in-beam electron ionization [102], and electrospray ionization (ESI) [103]. A combination of the techniques of desorption and tandem mass spectroscopy (MS/MS) has also been used for the charactmzation of chlorophylls and derivatives [ 104—107]. The latest research in this field coupled HPLC with MS, using as ionization source FAB [108-110] or atmosphoic pressure chemical ionization (APCI) [111-115]. 

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