Fast-Flow Liquid Chromatography

M. Katagi, M. Tatsuno, M. Nishikawa and H. Tsuchihashi, On-line solid-phase extraction liquid chromatography-continuous flow frit fast atom bombardment mass spectrometric and tandem mass spectrometric determination of hydrolysis products of nerve agents alkyl methylphosphonic acids by p-bromophenacyl derivatization, J. Chromatogr., A, 833, 169-179 (1999). 

In low-pressure liquid chromatography, the flow rate of the mobile phase must be optimized because this influences two band-broadening effects which are dependent on diffusion of sample molecules (i) the flow rate must be slow enough to allow effective partitioning between the mobile phase and the stationary phase and (ii) it must be fast enough to ensure that there is minimal diffusion along the column once the molecules have been separated. To allow for these opposing influences, a compromise flow rate must be used. 

Norwood, D.L., Kodo, N., Milhngton, D.S. (1988) Application of continuous-flow liquid chromatography/ fast-atom bombardment mass spectrometry to the analysis of diagnostic acylcamitines in human urine. Rapid Commun. Mass Spectrom., 2,269-272. 

Ashcroft, A.E., Herod, A.A., Manton, G. (1988) Applications and further developments of liquid chromatography-fast atom bombardment mass spectrometry (LC-FAB-MS) using a continuous flow probe. In Proceedings of the 36th ASMS Conference on Mass Spectrometry and Allied Topics, June 5-10, San Francisco, CA. 

Van Breemen, R.B, Canjura, F.L., and Schwartz, S.J., High-performance liquid chromatography-continuous-flow fast atom bombardment mass spectrometry of chlorophyll derivatives, J. Chromatogr., 542, 373, 1991. 

Moseley, M. A., Deterding, L. J., Tomer, K. B., and Jorgenson, J. W. Coupling of capillary zone electrophoresis and capillary liquid chromatography with coaxial continuous-flow fast atom bombardment tandem sector mass spectrometry, /. Chromatogr., 480, 197, 1989. 

Asperger A. et al., 2002. Trace determination of priority pesticide in water by means of high-speed online solid-phase extraction-liquid chromatography-tandem mass spectrometry using turbulent-flow chromatography columns for enrichment and a short monolithic column for fast liquid chromatographic separation. J Chromatogr A 960 109. 

As we have seen so far, libraries of hydrogenation catalysts are never composed of more than a few dozen members, up to 100 to 200 at the most. Consequently, modern analytical equipment such as gas chromatography (GC) or high-performance liquid chromatography (HPLC) equipped with an auto-sampler or even flow-through NMR systems are sufficient to handle the analysis of the entire library. Nevertheless, a few groups have initiated research towards the development of fast, sometimes parallel, analytical procedures. A few reviews have appeared on this subject [59]. Here, we will concentrate on the methods developed to analyze hydrogenation reactions, or methods that could likely be applied. 

M. A. Moseley, L. J. Deterding, K. B. Tomer, and J. W. Jorgenson. Nanoscale Packed-Capillary Liquid Chromatography Coupled with Mass Spectrometry Using a Coaxial Continuous-Flow Fast Atom Bombardment Interface. Anal. Chem., 63(1991) 1467-1473. 

In standard FAB, the surface of the matrix solution is depleted of analyte and suffers from radiational damage during elongated measurements. Refreshment of the surface proceeds by diffusion (limited by the viscosity of the matrix) or evaporation. Continuous-flow fast atom bombardment (CF-FAB) continuously refreshes the surface exposed to the atom beam. [107,108] The same effect is obtained in slightly different way by the frit-fast atom bombardment (frit-FAB) technique. [109,110] In addition, both CF-FAB and frit-FAB can be used for online-coupling of liquid chromatography (LC, Chap. 12) [111] or capillary electrophoresis (CE) to a FAB ion source. [112]... 

Wolfender, J.-L. et al.. Comparison of liquid chromatography/electrospray, atmospheric pressure chemical ionization, thermospray and continuous-flow fast atom bombardment mass spectrometry for the determination of secondary metabolites in crude plant extracts, J. Mass Spectrom. Rapid Commun. Mass Spectrom., S35, 1995. 

Figure A.3A.2 Selection of chromatography-mass spectrometry system for the analysis of a sample. Abbreviations APCI, atmospheric pressure chemical ionization CF, continuous flow Cl, chemical ionization El, electron impact FAB, fast atom bombardment GC/MS, gas chromatogra-phy/mass spectrometry LC/MS, liquid chromatography/mass spectrometry.

High-performance liquid chromatography (HPLC) and fast protein liquid chromatography (FPLC) rely on the same separation principles as the traditional chromatography columns, but tend to be much faster because of high flow rates that are possible due to the uniform bead size and the mechanical strength of the beads. See also Chapter 4, section 1.2.2. 

Ynddal, L., and Hansen, S. H. (2003). On-line turbulent-flow chromatography-high-performance liquid chromatography-mass spectrometry for fast sample preparation and quantitation.. /. Chromatogr. A. 1020 59-67. 

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