Mass Spectrometry Combined with Instrumental Chromatography

8 Mass Spectrometry Combined with Instrumental Chromatography 

TABLE 10.1 Detection Limits for ICP-MS for the Elements Listed in Table 9.2a 

Element ICP-MS Detection Limit (/xg/mL) Best Detection Limit from Table 9.2 

Note GFAA = graphite furnace atomic absorption. 

Source From Perkin-Elmer Instruments literature. With permission. 

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In principle, mass spectrometry is not suitable to differentiate enantiomers. However, mass spectrometry is able to distinguish between diastereomers and has been applied to stereochemical problems in different areas of chemistry. In the field of chiral cluster chemistry, mass spectrometry, sometimes in combination with chiral chromatography, has been extensively applied to studies of proton- and metal-bound clusters, self-recognition processes, cyclodextrin and crown ethers inclusion complexes, carbohydrate complexes, and others. Several excellent reviews on this topic are nowadays available. A survey of the most relevant examples will be given in this section. Most of the studies was based on ion abundance analysis, often coupled with MIKE and CID ion fragmentation on MS " and FT-ICR mass spectrometric instruments, using Cl, MALDI, FAB, and ESI, and atmospheric pressure ionization (API) methods. 

This pharmaceutical revolution could not have been achieved without the under-girdment of advanced analytical instrumentation. Mass spectrometry (MS) combined with liquid chromatography (LC) has enabled the characterization of novel potential dmgs as well as quantitative measurement in an increasingly complex milieu at an incredibly rapid throughput rate. Quantitation of dmgs in biological media such as... 

Liquid chromatography/mass spectrometry (LC/MS) is an analytical technique combining the advantages of an LC instrument with those of a mass spectrometer. 

Specifically for triazines in water, multi-residue methods incorporating SPE and LC/MS/MS will soon be available that are capable of measuring numerous parent compounds and all their relevant degradates (including the hydroxytriazines) in one analysis. Continued increases in liquid chromatography/atmospheric pressure ionization tandem mass spectrometry (LC/API-MS/MS) sensitivity will lead to methods requiring no aqueous sample preparation at all, and portions of water samples will be injected directly into the LC column. The use of SPE and GC or LC coupled with MS and MS/MS systems will also be applied routinely to the analysis of more complex sample matrices such as soil and crop and animal tissues. However, the analyte(s) must first be removed from the sample matrix, and additional research is needed to develop more efficient extraction procedures. Increased selectivity during extraction also simplifies the sample purification requirements prior to injection. Certainly, miniaturization of all aspects of the analysis (sample extraction, purification, and instrumentation) will continue, and some of this may involve SEE, subcritical and microwave extraction, sonication, others or even combinations of these techniques for the initial isolation of the analyte(s) from the bulk of the sample matrix. 

Other combinations are available. For example, liquid chromatographs connected to mass spectrometers (known as liquid chromatography-mass spectrometry [LC-MS]) are fairly common. Almost any combination of two instruments that can be thought of has been built. In addition, two of the same instruments can be connected so that the output from one is fed directly into the other for further separation and analysis. Examples include two mass spectrometers in an MS-MS arrangement and two different gas chromatography columns connected in a series, known as GC-GC. To keep up with these advances, one needs to have a working knowledge of the fundamental principles involved in the techniques and of the abbreviations used for the various instrumentation methods. 

Reverse-phase columns with a gradient elution in combination with UV-Vis spectrophotometers using photodiode-array (PDA) (Fig. 1.6) and spectrofiuorimeters are common devices employed in this technique. In a lesser extent, MS, tandem mass spectrometry (MS-MS), and nano liquid chromatography-electrospray ionization-quadrupole time-of-flight tandem mass spectrometry (nanoLC-nanoESI-Q-qTOF-MS-MS) has been used as detection system. This instrumentation has been mainly used in the analysis of dyes and proteinaceous media, and in some extent, in the analysis of drying oils and terpenoid varnishes [47,48],... 

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