Results Obtained from Mass Spectrometry

However, the data available suggest that the results obtainable from mass spectrometry will considerably facilitate the structural analysis of oligosaccharides and thus permit direct investigation of the products of partial hydrolysis of polysaccharides on the oligomer level. 

In total, 235 results for " Am were returned from all the exercises combined, with 152 results obtained by alpha spectrometry, 78 results obtained by gamma spectrometry, 3 results obtained by an unknown method and 2 results obtained by mass spectrometry. In recent exercises, about a quarter of the " Am results were obtained by gamma spectrometry, whereas about half of the " Am results from the exercises conducted in the late nineties had been obtained by this technique. The number of results obtained by mass spectrometry has been negligible and these results were not particularly accurate. In the... 

The recyclization of the aza-analogues of benzylium and naphthylmethylium ions to azatropylium ions and their benzylated analogues has been described by a variant of perturbation theory (PPP method) with bond orders on nonbonded atoms used as reactivity indices and the results correlated with the data obtained from mass spectrometry measurements <82KGSI673). 

This present article summarizes the results of these studies as well as related mass spectroscopic data obtained in the author s laboratories as well as some related studies by other workers 4-5>. For a review of the general principles of mass spectrometry the reader is referred to any of several books in this area 6 10> (see also 11-23> on information to be obtained from mass spectra). 

The threshold energy for the dissociative electron attachment process e" + SPg(g) = SF "(g) + F(g) has been measured directly by means of mass spectrometry ( .- ). In addition, mass spectrometric studies (5) have been reported on various electron transfer reactions which provide Independent estimates of the enthalpy for the above process. Presented below is a summary of the results derived from these measurements. Also included in the summary are results obtained from an electron-impact study ( ) of the process e + SFgCl(g) = SFg (g) + Cl(g). We assume that the fragment-ions are formed in each process with no excess or kinetic energies. As a result, the derived electron affinities represent lower limits to the true value. Other reported values of EA(SFg) include >1.465 eV (9), 3.2 eV (5) and 3.66 0.04 eV (10). The first two results are based on charge-transfer studies (5-9) while the latter value represents a direct measurement of EA using the magnetron technique (10). 

An 8 mg amount of an alkaloid was isolated from the plant Picrasma guassioides Bennet (Simaroubaceae), native to East Asia. The formula Ci H, iNjOj was obtained by mass spectrometry. What is the structure of the alkaloid given the NMR results 47 ... 

Many analytical laboratories are equipped with an infrared spectrometer, be it an older-style dispersive machine or a more modern Fourier-transform instrument. The results obtained from this particular technique are typically used in conjunction with the information gained from a variety of other analytical methods, such as nuclear magnetic resonance spectroscopy, mass spectrometry, ultraviolet-visible spectroscopy, or chromatography, in order to obtain information abbut a wide range of samples. 

Betti (1996) and co-workers used GD-MS for sample screening in isotopic measurements of zirconium, silicon, lithium, boron, uranium, and plutonium in nuclear samples. The results obtained from the GD-MS were compared with results from thermal ionization mass spectrometry (TIMS). For boron and lithium concentrations from //g/g to ng/g levels, isotopic ratios determined by GD-MS were comparable to TIMS in terms of accuracy and precision. Uranium isotopic ratios determined by GD-MS were also in good agreement with values measured by TIMS with regards to accuracy. Chartier et al. (1999) used GD-MS to analyze erbium and uranium in molybdenum-uranium fuel samples. The ratio of 166Er to 238U was then compared to numbers determined by thermal ionization mass spectrometry. The ratio of erbium to uranium was accurate to within 3% of the number determined by TIMS. 

Mechanistic studies performed with Freeh s pincer catalyst in the Heck reaction excluded catalytic cycles with the involvement of homogeneous palladium(O) species, as indicated by the results obtained from the (recently developed) dibenzyl-test, which is directly applicable under the reactions conditions applied [24aj. Dibenzyl formation was - in contrast to Heck reactions catalyzed by palladium(O) complexes of type [Pd(PR3)2, where Pd /Pd" cycles are operative - not detectable by gas chromatography-mass spectrometry (GC/MS) when reaction mixtures of aryl bromide, olefin, benzyl chloride ( 10 mol% relative to aryl bromide), catalyst, and base were thermally treated. On the other hand, experimental observations, such as quantitative poisoning experiments with metallic mercury and CS2, which were shown to eflfidently inhibit catalysis, as well as analysis of the reaction profiles showed sigmoidal-shaped kinetics with induction periods and hence indicated that palladium nanoparticles are the catalytically active form... 

To identify the specific aldehyde that is actually involved in the light-emitting reaction of living luminous bacteria, Shimomura et al. (1974a) extracted and purified the aldehyde from 40 g each of the bacterial cells of P. phosphoreum, Achromobacter (Vibrio or Photobacterium) fischeri, and an aldehydeless mutant of A. fischeri. The aldehyde fractions were purified, and then oxidized with Tollens reagent (silver oxide dissolved in ammonia) to convert the CHO group into the COOH group. Then the acids obtained were analyzed by mass spectrometry. The results indicated that P. phosphoreum had contained a mixture of aldehydes dodecanal (5%), tetradecanal (63%) and hexadecanal (30%), as shown in Table 2.2. Thus, tetradecanal was clearly predominant in... 

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