Mass spectrometers specific technologies

In addition to the discussion of the basics of mass spectromet-ric technologies presented herein, the reader will be directed, as appropriate, to cross-referenced chapters in this volume that provide more specifics on the MSI approaches. Even greater detail on both MS and MSI can be found in several excellent books and reviews (I-IO). 

The sensors in this section can also be utilized to detect chemicals in liquid through the bulk solution refractive index change induced by the presence of target chemicals. Since no recognition molecules are used, this type of chemical sensing may usually have low specificity. However, these sensors may perform excellently in conjunction with other technologies such as capillary electrophoresis, mass spectrometer, and liquid chromatography in chemical detection. 

Mass spectrometers have been used at some level in all of these types of investigations because of their unsurpassed sensitivity and specificity, their multicomponent analytical capability and, in some cases, their ability to provide precise and accurate isotope ratios. Traditional methods of analysis typically involve the collection of water and sediment samples, or biological specimens, during field expeditions and cmises on research vessels (R/Vs), and subsequent delivery of samples to a shore-based laboratory for mass spectrometric analyses. The recent development of field-portable mass spectrometers, however, has greatly facilitated prompt shipboard analyses. Further adaptation of portable mass spectrometer technology has also led to construction of submersible instruments that can be deployed at depth for in situ measurements. 

N cuum technology acceptance specifications for mass spectrometer leak detection devices, definitions 3/76... 

Compound specific stable isotope analysis using gas chromatography combined with an isotope ratio mass spectrometer - GC-IRMS (see also Chapter 7) - is now a mature analytical technique in environmental science and technology, especially in the area of contaminant source attribution and in assessing the biodegradation of contaminants.108 Several studies have focused on 13C/12C, 180/160 and 170/160 isotope ratio measurements for volatile organic and metalor-ganic compounds to study isotope fractionation effects and to identify contamination in the environment.109... 

It is not the intention of this chapter to provide a comprehensive treatment of FTMS technology and instrumentation, since excellent reviews exist (1). Instead, the focus will be on selected instrumental requirements which are crucial for the performance of a modern FTICR mass spectrometer, and which are not usually discussed elsewhere. Rather than striving for comprehensiveness, this paper is written with the intention of discussing specific design aspects in depth the emphasis is on the unique features of our mass spectrometer, since other instrumental aspects are elaborated on elsewhere in this book. 

The MudPlT approach is not without problems. A fully automated procedure as described requires (almost) continuous MS data acquisition for more than 15 hours, resulting in several thousands of mass spectra that put high demands on computers and bioinformatics. The procedure is limited by the ability of the mass spectrometer to rapidly switch between MS and MS-MS analysis under DDA control. With current technology, certainly not all peptides present can be analysed with both modes (Ch. 17.7.2). The power of the approach is greatly enhanced by performing a protein prefractionation, either by RPLC [8, 45] or by means of a protein-specific enrichment technique such as AfC (Ch. 17.4.1). 

The combination of HPLC with tandem mass spectrometers (LC/MS/MS) has revolutionized the analytical approach to TDM. This technology allows for direct analysis of biological specimens with minimal sample preparation, high sensitivity, specificity, precision, and high throughput. 

While the idea of combining gas chromatographs with mass spectrometers had already occurred in several laboratories in the late 1950 s, solution of the technological problems associated with interfacing the two methods was needed to stimulate general interest in this powerful analytical approach. Specifically, the development... 

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