Mass spectrometry preliminary analysis

Peters, G.R. and Beauchemin, D. (1992) Versatile interface for gas chromatographic detection or solution nebulization analysis by inductively coupled plasma mass spectrometry preliminary results./. Anal. At. Spectrom., 7, 965-969. 

Thermal properties of several chlorinated phenols and derivatives were studied by differential thermal analysis and mass spectrometry and in bulk reactions. Conditions which might facilitate the formation of stable dioxins were emphasized. No two chlorinated phenols behaved alike. For a given compound the decomposition temperature and rate as well as the product distribution varied considerably with reaction conditions. The phenols themselves seem to pyro-lyze under equilibrium conditions slowly above 250°C. For their alkali salts the onset of decomposition is sharp and around 350°C. The reaction itself is exothermic. Preliminary results indicate that heavy ions such as cupric ion may decrease the decomposition temperature. 

In contrast to direct mass spectrometry used in the El mode, ESI often requires specific pretreatments of the samples to purify the components of interest, to increase their yield of ionisation and consequently to improve selectivity and sensitivity. It is thus not a preliminary step of analysis but a method that forms part of an analytical strategy that allows the presence of well preserved high molecular long chain compounds to be shown before their fine characterisation by ESI techniques (Regert et al., 2003a Mirabaud, 2007 Mirabaud et al., 2007). 

In addition to GC/MS, high performance liquid chromatography (HPLC/MS) has been used to analyse natural resins in ancient samples, particularly for paint varnishes containing mastic and dammar resins [34]. A partial limitation of chromatographic techniques is that they do not permit the analysis of the polymeric fraction or insoluble fraction that may be present in the native resins or formed in the course of ageing. Techniques based on the direct introduction of the sample in the mass spectrometer such as direct temperature resolved mass spectrometry (DTMS), direct exposure mass spectrometry (DE-MS) and direct inlet mass spectrometry (DI-MS), and on analytical pyrolysis (Py-GC/MS), have been employed as complementary techniques to obtain preliminary information on the... 

Figure 13.7. The image of a fingerprint taken from a glass sheet surface (10,000 x 10,000 j,m). (Reprinted from Szynkowska, M. I. et al., 2007. Preliminary Studies Using Scanning Mass Spectrometry (TOF-SIMS) in the Visualisation and Analysis of Fingerprints, Imaging Sci. J., 55 180-187. With permission from Maney Publishing.) (See color insert.)...

Very few, if any, recent biomedical publications describe the use of ion-impact mass spectrometry without the use of GC or some other separation method because most biological samples are chemically complex. The production of clean and useful El mass spectrometric signals requires the substance of interest to be very pure, and thus direct El experiments are usually confined to preliminary studies of highly purified biomolecules or to studies on the metabolism of pure materials. Two publications that describe direct El methods applicable to biochemical analysis and neuropharmaceutical studies are those of Costa et al. (1992) and Karminski-Zamola et al. (1995). 

A.D. were found in old mines, and sizable slag deposits suggest at least some level of lead exploitation during Roman times (2). By the careful selection of Roman lead artifacts likely to have been manufactured in Carthage, and the use of lead isotope analysis, it may be possible to confirm the use of Tunisian lead ores during the Roman period. In this preliminary study, analysis of 22 curse tablets by electron microprobe analysis (EMPA) and six tablets by thermal ionization mass spectrometry (TIMS) suggest that these artifacts might be used to better understand Roman lead use and trade. 

Croft, D. J. and Pye, K. (2003). The potential use of continuous-flow isotope-ratio mass spectrometry as a tool in forensic soil analysis A preliminary report. Rapid Commun. Mass Spectrom. 17, 2581-2584. 

Both fractions obtained from crackers extracted less than one week after baking had strong cracker-like aromas. The Freon 113 fraction had a cracker, roasted grain, cooked rice aroma while the ethyl acetate fractions had a cracker, sweet baked good, burnt butter aroma. A preliminary analysis of the two fractions by gas chromatography-mass spectrometry on a 25 m by. 22 mm methyl silicone column between 700 and 1800 retention indices showed the compounds listed in Table 2. 

It is possible to use techniques in which the additives can be determined by direct analysis of the sample, such as nuclear magnetic resonance (NMR) spectrometry, ultraviolet (UV) spectrometry, and UV desorption-mass spectrometry. These techniques are very useful when the concentrations of additives in the polymer are high. However, when additives are present in trace levels, it is necessary to carry out a preliminary extraction/concentration step before analysis. Some of the most common additives used in plastics materials are presented in Table 1. 

Screening of estuarine and marine sediment samples by automated pyrolysis mass spectrometry combined with factor-discriminant analysis leads to a useful classification related to the geographical position and the sources of the organic matter. The mass spectral data give preliminary information about the organic matter composition. Analysis of the characteristic mass peaks m/z=86 and 100 by PMSMS and PGCMS points to bacterial poly-alkanoates in the mud fraction of the river sediments. 

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