Introduction

Liquid chromatography (LC) can often separate complex mixtures but simple detectors (e.g. ultraviolet-visible UV/Vis) do not allow identification of the individual components. Comparison of retention data and spiking with known standards is normally required to provide evidence of composition but this may lead to erroneous results as absolute identification is not possible. Development of diode array detection has somewhat alleviated the problem but not removed it entirely. Absorbance requires the presence of a chromophore in the molecule and, as such, UV/vis spectra do not enable absolute identification but are frequently used to confirm identity through comparison of recorded spectra with reference spectra.

Mass spectrometry (MS) provides a unique means of determining the presence of a compound in a mixture by producing a mass spectrum which will aid or confirm its identification. The relative molar mass (RMM) and/or structurally important information may also be obtained from the mass spectrum.

The combination of a separation technique with MS provides a powerful instrumental method for the analytical scientist. Modern gas chromatography-mass spectrometry (GC-MS) instrumentation, having overcome the obstacles associated with coupling them to each other, has matured into an easy-to-use benchtop technique. The interfacing of high performance liquid chromatography (HPLC) with a mass tive characterization by capillary supercritical fluid chromatography/Fourier transform infrared microspec-trometry. Analytical Chemistry 60: 427-433.

Sabo M, Gross J, Wang J and Rosenberg IE (1985) On-line high-performance liquid chromatography/Fourier transform infrared spectrometry with normal and reverse phases using an attenuated total reflectance flow cell. Analytical Chemistry 57: 1822-1826.

Scott RPW, Scott CG, Munroe M and Hess J Jr. (1974) A transport interface for LC/MS. The Poisoned Patient: The Role of the Laboratory, p. 395. New York: Elsevier.

Somsen GW, Hooijschuur EWJ, Goopijer C, Brinkman UATh and Velthorst NH (1996) Coupling of reversed-phase liquid column chromatography and Fourier transform infrared spectrometry using post column on-line extraction and solvent elimination. Analytical Chemistry 68: 746-752.

spectrometric detector (LC-MS) poses many problems, not least the different sample requirements of the respective instruments, i.e. liquid and vapour. The purpose of this article is to describe those interfaces that are most routinely used in LC-MS applications and, as such, will cover aspects of ionization methods and, to a lesser extent, mass analysers.

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Solar Panel Basics

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