Mass spectrometry separation techniques

From the characteristics of the methods, it would appear that FD-MS can profitably be applied to poly-mer/additive dissolutions (without precipitation of the polymer or separation of the additive components). The FD approach was considered to be too difficult and fraught with inherent complications to be of routine use in the characterisation of anionic surfactants. The technique does, however, have a niche application in the area of nonpolar compound classes such as hydrocarbons and lubricants, compounds which are difficult to study using other mass-spectrometry ionisation techniques. 

SEC-ESI-FTMS combines the size separation based technique of SEC with one of the most powerful mass spectrometric techniques of FTMS offering high mass accuracy (ppm), ultrahigh resolving power (>10(i) 6) and the capability to perform tandem mass spectrometry. The technique enables generation of oligomer elution profiles, which can be used for accurate calibration of standard SEC data. Coupling of SEC to ESI-MS is further described in ref. [710],... 

Halket and Lisboa (25) examined several Vitamin D derivatives by capillary gas chromatography coupled with mass spectrometry. This technique offered the advantages of great sensitivity and separating power. Retention times and fragmentation patterns for ergocalciferol, cholecalciferol and calcitriol were reported. 

The analytical approach applied in the PoweU et at. (2005) study represents a major advancement in our current study of the chemical structure of DOM. SDS-PAGE remains one of the few methods that wiU allow separation and purification of intact dissolved proteins proteomics, as applied by PoweU et at. (2005), is now routinely applied in the biochemical and biomedical fields but is rarely applied in the environmental sciences. A major advantage of these mass spectrometry based techniques (i.e., proteomics) is the relatively smaU quantity of material required for the analysis this opens up the possibility for analyzing peptides and proteins in total DOM with little or no pre-concentration. However, the presence of salts stUl needs to be minimized before effective mass spectra can be generated. A recent review by Mopper et at. (2007) highlights the application of high-resolution analytical techniques to study marine DOM composition, and we refer the reader to this review for a more comprehensive discussion of recent analytical advances. 

Mass spectrometry (MS) techniques have been long used as follow-on techniques after 2D-PAGE separation to identify shifted or new spots discovered on the gel. However, several MS-based techniques are now being used in ways that are rapidly superseding 2D-PAGE as a means to rapidly, accurately, and reproducibly measure and identify proteins and polypeptides in mixtures. 

As GC techniques became more refined and were generally accepted, due to the superior separation and resolution potential of modern capillary columns, they took preference, especially in the analysis of PAH in car exhaust emissions and air particulates. In combination with an FID-detector, which, in contrast to the UV-detectors used frequently in HPLC analysis, has a nearly uniform response factor for hydrocarbons, or coupled to mass spectrometry, this technique must now be considered the method of first choice for a reliable and reproducible determination of PAH traces in a wide range of matrices. The introduction of more sensitive (photo-ionisation detector - PID) and specific detectors, such as the nitrogen-phosphorus (NPD)... 

Mass spectrometry-based techniques to identify combinatorial libraries make use of ESI-MS [90], HPLC/ESI-MS [91], MALDI-MS [92], and a combination of ESI with IMS [93,94] and FT-ICR-MS [95,96]. The last one has the advantage that the molecular mass of the analyte can be measured at ultrahigh resolution to allow the separation of nominal isobaric ions. A better fingerprint of the library can be obtained at high mass resolution. 

Nd in samples. Unfortunately, mass spectrometry is not a selective technique. A mass spectrum provides information about the abundance of ions with a given mass. It cannot distinguish, however, between different ions with the same mass. Consequently, the choice of TIMS required developing a procedure for separating the tracer from the aerosol particulates. 

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