Introduction

The tremendous technological developments that have followed the initial interfacing of gas chromato-graphs with mass spectrometers together with the phenomenal advances in computerized data handling have provided an analytical technique that finds practically universal application. The biomedical sciences afford an enormous range of applications of this instrumentation where its full potential as a primary method for the separations and identification of extremely complex mixtures is clearly demonstrated.

The applications can be grouped into three broad categories based upon the nature of the analytes:

• Small volatile molecules, e.g. metabolites, xeno-biotics (drugs, toxins, etc), food components

• Large labile molecular species, e.g. biomacro-molecules and even whole cells

• Isotopomers (molecules differing only in isotopic composition), e.g. tracer studies, isotopic labelling, breath gas diagnostics, natural abundance studies

The analysis of small volatile molecules, perhaps after derivatization, is the major application area; particular biomedical applications in clinical chemistry and occupational hygiene are illustrated below. Others are exemplified under the headings sport, environment, food and forensics. The analysis of bio-macromolecules and whole cells is another rapidly expanding field but using other mass spectrometric and separatory techniques (electrospray, atmospheric pressure and matrix assisted laser desorption ionization; see also LC-MS, CE-MS). Gas chromatogra-phy-mass spectrometry (GC-MS) of pyrolysates can provide information about otherwise intractible materials.

The elucidation of mechanisms and biochemical pathways using tracer and labelling techniques is an example of the third category of applications which is also a rapidly expanding area with the wider availability of stable as opposed to radioactive labelled compounds. The ability to separate and distinguish between components in a complex mixture that differ solely in their isotopic composition allows exogenous materials to be distinguished from endogenous species; it also provides a means of improving quantitation (via isotope dilution) and allows dynamic studies of metabolism or dysfunction to be undertaken. It is this latter area of GC-SIRMS (GC-stable isotope ratio MS) that will be emphasized.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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