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Liquid chromatography–mass spectrometry (LC–MS) is an analytical chemistry technique that combines the physical separation capabilities of liquid chromatography (or HPLC) with the mass analysis capabilities of mass spectrometry (MS). Coupled chromatography – MS systems are popular in chemical analysis because the individual capabilities ...
A modern self-contained HPLC Schematic representation of an HPLC unit (1) solvent reservoirs, (2) solvent degasser, (3) gradient valve, (4) mixing vessel for delivery of the mobile phase, (5) high-pressure pump, (6) switching valve in "inject position", (6') switching valve in "load position", (7) sample injection loop, (8) pre-column (guard column), (9) analytical column, (10) detector (i.e ...
The sample is first subjected to analysis by HPLC and then is subjected to mass analysis. Different types of mass analyzers, ToF, qudrupole, etc., can be used in the MS. [5] Common solvents used in normal or reversed phase LC such as water, acetonitrile, and methanol are all compatible with ESI, yet a LC grade solvent may not be suitable for MS.
The mobile phase consists of the sample being separated/analyzed and the solvent that moves the sample through the column. In the case of HPLC the mobile phase consists of a non-polar solvent(s) such as hexane in normal phase or a polar solvent such as methanol in reverse phase chromatography and the sample being separated. The mobile phase ...
The basic methods of separation in HPLC rely on a mobile phase (water, organic solvents, etc.) being passed through a stationary phase (particulate silica packings, monoliths, etc.) in a closed environment (column); the differences in reactivity among the solvent of interest and the mobile and stationary phases distinguish compounds from one ...
Silica gel particles are commonly used as a stationary phase in high-performance liquid chromatography (HPLC) for several reasons, [13] [14] including: High surface area: Silica gel particles have a high surface area, allowing direct interactions with solutes or after bonding of variety of ligands for versatile interactions with the sample molecules, leading to better separations.
However, the possibility to record an EI spectrum from an HPLC application remained a challenge for a long time. The first Direct-EI prototype was first presented in 2002 [5] and proposed an innovative approach that improved interfacing performance compared to that of particle beam and opened new opportunities for LC-MS applications.
Ammonium formate can be used as a mobile phase additive in high performance liquid chromatography (HPLC), and is suitable for use with liquid chromatography-mass spectrometry (LC/MS). The p K a values of formic acid and the ammonium ion are 3.8 and 9.2, respectively.