Sách Gas Chromatography-Mass Spectroscopy

Gas Chromatography-Mass Spectroscopy

Introduction

Mass Spectroscopy is a powerful analytical technique which can provide a myriad of information

about analytes in complex mixtures. In principle mass spectroscopy separates ions of a sample based on

their mass to charge ratio (m/z). Qualitative as well as quantitative information for both inorganic and

organic compounds can be obtained, as well as structural information about a wide variety of molecular

species. The use of high resolution instruments allows the determination of isotopic ratios of atoms in

samples and with specialized instrumentation the structure and composition of solid surfaces can be

investigated. The first mass spectrometers were developed in the 1920's with the first commercial

instrument becoming available in the 1950's. Many significant developments have occurred since that time

not only in instrumentation but also in understanding of the fundamental processes occurring within the

mass spectrometer. Some significant instrumental advances include the development of double focusing

instruments, interfacing mass spectrometers to chromatographic separation techniques, the use of tandem

mass spectrometer and several new ionization techniques have been developed. Fundamental understanding

of the behavior of ions in a magnetic field is the basis for applying mass spectroscopy to the determination

of chemical composition of a sample. Additional developments in the understanding of fragmentation of

molecular species in the ion source allow the structural analysis and identification of complex molecules.

Further improvements have included the application of Fourier transform, which greatly improves mass

resolution and signal-to-noise ratios. Mass spectroscopy has matured into a sophisticated and powerful tool

which is widely used in chemical and biochemical analysis.