Mass spectrometry combined with HPLC

Gas Chromatography (gc). A principal advantage of gas chromatography has been the faciUty with which it can be combined with mass spectrometry for amino acid identification and confirmation of purity. The gc-mass spectrometry combination offers the advantage of obtaining stmctural information rather than the identification by retention time in hplc. 

Multiple mass analyzers exist that can perform tandem mass spectrometry. Some use a tandem-in-space configuration, such as the triple quadrupole mass analyzers illustrated (Fig.3.9). Others use a tandem-in-time configuration and include instruments such as ion-traps (ITMS) and Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS or FTMS). A triple quadrupole mass spectrometer can only perform the tandem process once for an isolated precursor ion (e.g., MS/MS), but trapping or tandem-in-time instruments can perform repetitive tandem mass spectrometry (MS ), thus adding n 1 degrees of structural characterization and elucidation. When an ion-trap is combined with HPLC and photodiode array detection, the net result is a profiling tool that is a powerful tool for both metabolite profiling and metabolite identification. 

High-performance liquid chromatography was combined with electrospray ionization mass spectrometry (i.e., HPLC-ESI-MS) to differentiate quantitatively crude natural extracts of various environmental samples [711, 712] and with NMR (i.e., HPLC-MS-NMR) for quantitation measurement [713]. 

Lewis et al. [714] combined HPLC with Tandem Electrospray Mass Spectrometry (i.e., HPLC-ESI-MS-MS) for the determination of sub-ppb levels of toxins in extracts of fish. 

Mass spectrometry has gained widespread application for the characterization of synthetic peptides and has led, in combination with HPLC, to the identification of accompanying byproducts such as polysulfides 17 ... 

Mass spectrometry (MS), employing most of the ionization techniques, has been used either independently, or in combination with HPLC, for the determination of the dissociation scheme of paclitaxel or for the identification of taxanes and paclitaxel metabolites. Tandem MS has enhanced identification and structure elucidation capabilities in the analysis of either biological or plant samples. 

Isotope dilution mass spectrometry is an accurate and sensitive technique for determining toxic trace elements in food matrices. Lead, cadmium, and thallium have been analyzed rapidly down to very low levels by ICP-MS. The latter technique is particularly useful for simultaneous measurement of a wide range of elements. Because the toxicity of an element can be highly dependent on its chemical form, ICP-MS is also useful in the speciation of toxic minerals in foodstuffs by combination with HPLC or SEC. 

Mass spectrometry with electrospray ionization (ESl-MS) is especially powerful when combined with HPLC because the two techniques can be used in tandem. With such an instrument the effluent from the HPLC is introduced directly into an ESI mass spectrometer. Thus, chromatographic separation of peptides in a mixture and direct structural information about each of them are possible using this technique. 

Mass spectrometry (MS) is increasingly being combined with reverse phase HPLC or CZE in order to add an additional dimension to the data that a traditional detection system would not provide. A two-dimensional EC-CZE system with mass... 

The luciferin produces a blue oxidation product during its purification process. In the DEAE chromatography of luciferin, this blue compound is eluted before the fractions of luciferin. The fractions of the blue compound were combined and purified by HPLC on a column of Hamilton PRP-1 (7 x 300 mm) using methanol-water (8 2) containing 0.1% ammonium acetate. The purified blue compound showed absorption peaks at 234, 254, 315, 370, 410, 590 (shoulder) and 633 nm. High-resolution FAB mass spectrometry of this compound indicated a molecular formula of C l C Nai m/z 609.2672 (M - Na + 2H)+, and mlz 631.2524 (M + H)+]. These data, together with the HNMR spectral data, indicated the structure of the blue compound to be 8. 

For off-bead analysis, coupling between chromatographic separation and mass spectrometric detection has proven especially powerful. The combination between high performance liquid chromatography (HPLC) and electrospray ionisation mass spectrometry has the advantage that purity of product mixtures can be coupled on-line with the product identification. 

In the first chapter, I have discussed the limitations of high performance liquid chromatography (HPLC) and mass spectrometry when used in isolation and how the combination of the two allows these to be overcome. In this chapter, the effect of combining the two techniques with regard to the individual performance characteristics are explored. 

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