Chromatography-mass spectrometry interfaces

Multidimensional or hyphenated instmments employ two or more analytical instmmental techniques, either sequentially, or in parallel. Hence, one can have multidimensional separations, eg, hplc/gc, identifications, ms/ms, or separations/identifications, such as gc/ms (see CHROMATOGRAPHY Mass spectrometry). The purpose of interfacing two or more analytical instmments is to increase the analytical information while reducing data acquisition time. For example, in tandem-mass spectrometry (ms/ms) (17,18), the first mass spectrometer appHes soft ionization to separate the mixture of choice into molecular ions the second mass spectrometer obtains the mass spectmm of each ion. 

The possibiHties for multidimensional iastmmental techniques are endless, and many other candidate components for iaclusion as hyphenated methods are expected to surface as the technology of interfacing is resolved. In addition, ternary systems, such as gas chromatography-mass spectrometry-iafrared spectrometry (gc/ms/ir), are also commercially available. 

Gas chromatography/mass spectrometry (GC/MS) is the synergistic combination of two powerful analytic techniques. The gas chromatograph separates the components of a mixture in time, and the mass spectrometer provides information that aids in the structural identification of each component. The gas chromatograph, the mass spectrometer, and the interface linking these two instruments are described in this chapter. 

The ion spray liquid chromatography/mass spectrometry (LC-MS) interface coupled via a postsuppressor split with an ion chromatography (IC) has been used in the analysis of alcohol sulfates. The IC-MS readily produces the molecular weight while the tandem mass spectrometric detection IC-MS-MS provides structural information [305]. 

The characteristics of an ideal liquid chromatography-mass spectrometry interface have been discussed, with emphasis having been placed upon the major incompatibilities of the two component techniques that need to be overcome to allow the combination to function effectively. 

Merritt DA, KH Freeman, MP Ricci, SA Studley, JM Hayes (1995) Performance and optimization of a combustion interface for isotope ratio monitoring gas chromatography/mass spectrometry. Anal Chem 67 2461-2473. 

The method for chloroacetanilide soil metabolites in water determines concentrations of ethanesulfonic acid (ESA) and oxanilic acid (OXA) metabolites of alachlor, acetochlor, and metolachlor in surface water and groundwater samples by direct aqueous injection LC/MS/MS. After injection, compounds are separated by reversed-phase HPLC and introduced into the mass spectrometer with a TurboIonSpray atmospheric pressure ionization (API) interface. Using direct aqueous injection without prior SPE and/or concentration minimizes losses and greatly simplifies the analytical procedure. Standard addition experiments can be used to check for matrix effects. With multiple-reaction monitoring in the negative electrospray ionization mode, LC/MS/MS provides superior specificity and sensitivity compared with conventional liquid chromatography/mass spectrometry (LC/MS) or liquid chromatography/ultraviolet detection (LC/UV), and the need for a confirmatory method is eliminated. In summary,... 

Interfaces for Supercritical Fluid Chromatography/Mass Spectrometry... 

Sakairi, M. and Kato, Y., Multi-atmospheric pressure ionization interface for liquid chromatography-mass spectrometry, ]. Chromatogr. A. 794, 391, 1998. 

The mass spectrometer is mainly used as a mass detector in chromatography (GC, SFC, HPLC, SEC, TLC). With the great variety of interfaces, ionisation modes and mass spectrometers, chromatography-mass spectrometry is highly diversified. High-resolution separations combined with accurate mass measurements and element-sensitive detection (MIP, ICP) have been reported. 

Simpson, R. C. Fenselau, C. Hardy, M. R. Townsend, R. R. Lee, Y. C. Cotter, R. J. Adaptation of a thermospray liquid chromatography/mass spectrometry interface for use with alkaline exchange liquid chromatography of carbohydrates. Anal. Chem. 1990, 62, 248-252. 

The introduction and eventual commercialization of matrix-assisted laser desorption/ionization (MALDI) and electrospray (ESI) allowed biomarker status to be extended to proteins in 1996.15"17 With a few exceptions, ESI has been used in conjunction with extractions and high-pressure liquid chromatography (UPLC) interfaced with mass spectrometry. MALDI, on the other hand, has been widely adapted for rapid analysis of intact organisms, supported by bioinformatics.1819... 

Blakley C.R. and Vestal M.L., 1983. Themospray interface for liquid chromatography/mass spectrometry. Anal Chem 55 750. 

C. R. Blakley and M. L. Vestal. Thermospray Interface for Liquid Chromatography/Mass Spectrometry. Anal Chem., 55(1983) 750-754. 

All gas chromotography/mass spectrometry (GC/MS) analyses of monomers and intermediates were performed on a Finnigan 1020 GC/MS using a 30-m RSL-150 fused silica capillary column. Liquid chromatography/mass spectrometry (LC/NS) was performed on a Finnigan 4500 mass spectrometer using acetonitrile-water eluent and a moving belt LC/MS interface. 

D.E. Games, P. Hirter, W. Kuhnz, E. Lewis, N.C.A. Weerasinghe and S.A. Westwood, Studies of combined liquid chromatography-mass spectrometry with a moving-belt interface, J. Chromatogr., 203 (1981) 131-138. 

M.A. Baldwin and F.W. McLafferty, Liquid chromatography-mass spectrometry interface. I The direct introduction of liquid solutions into a chemical ionization mass spectrometer, Org. Mass Spectrom., 7 (1973) 1111-1112. 

Based on a new technology, particle beam enhanced liquid chromatography-mass spectrometry expands a chemist s ability to analyse a vast variety of substances. Electron impact spectra from the system are reproducible and can be searched against standard or custom libraries for positive compound identification. Chemical ionization spectra can also be produced. Simplicity is a key feature. A simple adjustment to the particle beam interface is all it takes. 

In recent years, also the number of articles concerning HILIC stationary phases has enormously increased, especially as regards the hydrophilic interactions that resolve some important problems separation and resolution of less retained compound in reversed phase chromatography. With this novel stationary phase, where the silica surface is covered with cross-linked diol groups to increase polar selectivity in hydrophilic conditions, is possible obviate to the use of normal phase with high water content. This allows facilitating the interfacing with sensible and selective detection instruments, such as mass spectrometer with ESI source. The HILIC stationary phase was often chosen to interface the mass spectrometry detector, because it would be... 

Puig et al. [450] determined ng/1 levels of priority methyl-, nitro-, and chloro-phenols in river water samples by an automated on-line SPE technique, followed by liquid chromatography-mass spectrometry (LC-MS) using atmospheric pressure chemical ionization (APCI) and ion spray interfaces. 

Winkler, P.C. Perkins, D.D. Williams, D.K. Browner, R.F. Performance of an Improved Monodisperse Aerosol Generation Interface for Liquid Chromatography/Mass Spectrometry. Anal. Chem. 1988,60,489-493. 

Millington, D.S. Yorke, D.A. Bums, P. A New Liquid Chromatography-Mass Spectrometry Interface. Adv. Mass Spectrom. 1980, SB, 1819-1825. 

TFA is advantageous in that it enhances the peak shape and efficiency for some polar compounds and its higher volatility is more desirable in liquid chromatography-mass spectrometry (LC-MS) operative conditions. The interfacing of LC methodologies with MS is discussed later in Section 2.3.1.4. 

Somsen, G. W, Mol, R., and de Jong, G. J. (2003). On-line micellar electrokinetic chromatography-mass spectrometry feasibility of direct introduction of non-volatile buffer and surfactant into the electrospray interface. /. Chromatogr. A 1000, 953—961. 

Til. Ozaki, H., Itou, N., Terabe, S., Takada, Y., Sakairi, M., and Koizumi, H. (1995). Micellar electrokinetic chromatography mass-spectrometry using a high-molecular-mass surfactant - online coupling with an electrospray-ionization interface.. Chromatogr. A 716, 69—79. 

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