Organic compound analysis mass spectrometer

The mass spectrometer GC detector has a high degree of compatibility with the purge and trap technique, and GC/MS has been employed widely with this isolation and concentration procedure for the analysis of volatile organic compounds. The mass spectrometer is strongly recommended for samples where there is a possibility of unexpected compounds, and for broad spectrum analyses f 6J of poorly defined samples. 

In the analysis of semivolatile organic compounds the mass spectrometer is again the detector of choice, because of the increased confidence in peak identification... 

St-Germain F, Mamer O, Brunet J, et al. 1995. Volatile organic compound analysis by an inertial spray extraction interface coupled to an ion trap mass spectrometer. Anal Chem 67 4536-4541. 

The high temperatures in the MHD combustion system mean that no complex organic compounds should be present in the combustion products. Gas chromatograph/mass spectrometer analysis of radiant furnace slag and ESP/baghouse composite, down to the part per biUion level, confirms this behef (53). With respect to inorganic priority pollutants, except for mercury, concentrations in MHD-derived fly-ash are expected to be lower than from conventional coal-fired plants. More complete discussion of this topic can be found in References 53 and 63. 

Principles and Characteristics Mass-spectral analysis methods may be either indirect or direct. Indirect mass-spectral analysis usually requires some pretreatment (normally extraction and separation) of the material, to separate the organic additives from the polymers and inorganic fillers. The mass spectrometer is then used as a detector. Direct mass-spectrometric methods have to compete with separation techniques such as GC, LC and SFC that are more commonly used for quantitative analysis of polymer additives. The principal advantage of direct mass-spectrometric examination of compounded polymers (or their extracts) is speed of analysis. However, quite often more information can be... 

The MALDI-TOF technique was first developed for the analysis of large biomolecules (Karas and others 1987). This technique presents some interesting characteristics. Of these, the high speed of analysis and the sensitivity of the technique have been pointed out as important advantages compared with other methods. In MALDI the samples are cocrystallized with a matrix that is usually composed of organic compounds, such as 3,5-dimethoxy-4-hydroxycinnamic acid (sinapic acid), 2, 4, 6 -trihydroxyacetophenone, a-cyano-4-hydroxycinnamic acid (alpha-cyano or alpha-matrix), and 2,5-dihydroxybenzoic acid (DHB). After the cocrystallization, the laser is fired and the matrix absorbs energy and allows a soft ionization of the samples. Afterward the ions are analyzed by a TOF mass spectrometer. 

Table I contains a list of some of the compounds that have been submitted to this type of analysis. The recovery data is intended to be illustrative only since recoveries depend strongly on several important method variables. Recoveries are expressed as a percentage of the amount added to organic free water. The purge time was 11-15 minutes with helium or nitrogen, the purge rate was 20 ml/minute at ambient temperature, and the trap was Tenax followed by Silica Gel. Data from the 5 ml sample was obtained with a custom made purging device and either flame ionization, microcoulo-metric, or electrolytic conductivity GC detectors. Data from the 25 ml sample was obtained with a Tekmar commercial liquid sample concentrator and a mass spectrometer GC detector using CRMS.

Analysis of the Mixture of Organic Compounds from the Soil. The crude fractions were analyzed using a LKB-2091 capillary gas chromatograph/mass spectrometer/data analysis system (CGC/MS/DA). The capillary column used was a J W DB-1, 60 m x 0.32 mm, connected directly to Ae ion source of the mass spectrometer. Up to 1.0 tfL of a solution of the sample in an appropriate solvent was injected directly onto the column at 40 °C, whereupon the column temperature was immediately raised to 100 for 4 min, and programmed to 310 °C at a rate of 10°/min. and held there for 30 min. 

Sampling and Analysis. A frozen slice of bread was cut in pieces and stacked in an enlarged sample flask of an aroma isolation apparatus according to MacLeod and Ames (74). Volatile compounds were trapped on Tenax TA and afterwards thermally desorbed and cold trap injected in a Carlo Erba GC 6000 vega equipped with a Supelcowax 10 capillary column (60 m x 0.25 mm i.d.) and a flame ionisation detector. Similar GC conditions were used for GC-MS identification of volatile compounds by dr. M.A. Posthumus (Dept. Organic Chemistry, VG MM7070F mass spectrometer at 70 eV El, 75). 

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