Interface direct liquid introduction

Direct liquid introduction interface. An interface that continuously passes all, or a part of, the effluent from a liquid chromatograph to the mass spectrometer the solvent usually functions as a chemical ionization agent for ionization of the solute. 

Seven different LC-MS interfaces are described in Chapter 4, with particular emphasis being placed on their advantages and disadvantages and the ways in which the interface overcomes (or fails to overcome) the incompatibilities of the two techniques. The earlier interfaces are included for historical reasons only as, for example, the moving-belt and direct-liquid-introduction interfaces, are not currently in routine use. The final chapter (Chapter 5) is devoted to a number of illustrative examples of the way in which LC-MS has been used to solve various analytical problems. 

El may be used with the moving-belt and particle-beam interfaces. Cl with the moving-belt, particle-beam and direct-liquid-introduction interfaces, and FAB with the continuous-flow FAB interface. A brief description of these ionization methods will be provided here but for further details the book by Ashcroft [8] is recommended. 

The direct-liquid-introduction interface is shown schematically in Figure 4.2. This system is effectively a probe, at the end of which is a pinhole of approximately 5 p.m diameter, which abuts a desolvation chamber attached to the ion source of the mass spectrometer. The eluate from an HPLC column is circulated... 

The thermospray interface overcame many of the problems encountered with the moving-belt and direct-liquid-introduction interfaces and with the advent of this, LC-MS became a routine analytical tool in a large number of laboratories. This was reflected in the fact that this was the first type of interface made available commercially by the majority of the manufacturers of mass spectrometers. 

J Apffel, U Brinkman, R Frei, E Evers. Gas-nebulized direct liquid introduction interface for liquid chromatography/mass spectrometry. Anal Chem 55 2280-2284, 1983. 

In order to avoid precipitation of non-volatile analytes at the iimer wall of the tube, tapering of the outlet was investigated [29-31]. The difficulty with this approach is that tapering is art rather than science. The latter problem was solved by the introduction in 1980 of a small diaphragm as solvent restriction [32], leading to the direct liquid introduction interface (Ch. 4.5). 

Sample in Diaphragm Desoivation chamber Figure 4.6 Direct liquid introduction interface. 

Direct liquid introduction interface. An interface that continuously passes all, or a part of, the... 

WMA Niessen. Review of direct liquid introduction interfacing for LC/MS part I instrumental aspects. Chromatographia, 21 277, 1986. 

Bieri RH, Greaves J. 1987. Characterization of benzo[a]pyrene metabolites by high performance liquid chromatography-mass spectrometry with a direct liquid introduction interface and using negative chemical ionization. Biomed Environ Mass Spectrum 14 555-561. 

Eckers, C. Skrabalak, D.S. Henion, J. On-line direct liquid introduction interface for micro-liquid chro-matography/mass spectrometry application to drug analysis. Clin.Chem., 1982, 28, 1882-1886... 

Atmospheric-pressure chemical ionisation was favoured by Horning et al. [3], whereas (2) Scott et al. [4] applied a moving-wire system which became transformed and finally resulted in the moving-belt interface. (3) The research of Arpino and his co-workers [5] led further in the direction initiated by Talroze [2], which after all had brought about the direct liquid introduction interface. 

The first two commercially available LC-MS interfaces were the moving-belt interface and the direct liquid introduction interface. These hyphenated techniques promoted pharmacological research at several stages of drug development. The polar pharmaceutical compounds that were under research in pharmacological experiments, their polar by-products from chemical synthesis or even the very polar... 

First paper on LC-MS by the group of Tal roze 1974 A variety of LC-MS interfaces presented at the 9th International Symposium on Advances in Chromatography, Houston, Texas 1976 Commercial introduction of the moving-belt interface 1980 Commercial introduction of the direct liquid introduction interface... 

In the past 10 years, the manner in which LC-MS analysis is performed has significantly changed. While in the past it was necessary to choose the most appropriate LC-MS interface for a particular application from a list of five possibilities, e.g., the moving-belt interface, the direct-liquid introduction interface, the thermospray interface, the particle-beam interface, and the continuous-flow fast-atom bombardment interface, today all LC-MS technologies are based on API. The two most important... 

It is much more difficult to couple HPLC on-hne with El and Cl sources (Ardrey 2003) since the voliune of vaporized mobile phase is up to 10 times larger than that of the liquid, far beyond the pumping capabilities of any realistic vacuum system unless the flow rate is restricted by a post-column split to a few xL.min, as in the so-called direct liquid introduction interfaces (Abian 1999) for Cl and (less commonly) El these interfaces... 

High performance liquid chromatography is well established as a tool for the separation of mixtures of labile biological substances, but its combination with mass spectrometry (LC/MS) remains fraught with difficulties as a valid analytical procedure. Several new types of direct liquid introduction interfaces (as opposed to transport interfaces) have been developed recently and appear to offer promise for the future. The thermospray interface 44) has been used successfully for amino acids, small peptides, nucleosides, antibiotics and glucuronides. The spectra are the relatively simple ones commonly obtained from soft ionization methods and resemble those obtained by FABMS. A gas nebulizer interface has enabled representative spectra (resembling those generated from DCI) to be... 

Apffel, j. a., U. a. T. Brinkman, R. W. Frei, and E. A. I. M. Evers Gas-Nebulized Direct Liquid Introduction Interface for Liquid Chromatography/Mass Spectrometry. Analyt. Chemistry 55, 2280 (1983). 

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