exclusively at removal of active hydrogen atoms(s) from protonic functional groups by the action of a suitable reagent, giving rise to a derivative with the hydrogen atoms substituted by less active functional groups.

Development of a particular derivatization method requires a good knowledge of organic chemistry, taking into consideration as many reaction mechanisms as possible. This is particularly true for the derivatiz-ation of protein amino acids, where so many different chemical groups are involved, such that a remark has been made about having here 'the whole of Beilstein'! The history of their more or less successful derivatiz-ation can be found in the book Amino Acid Analysis by Gas Chromatography (see Further Reading).

In general, the nature of the compounds to be analysed and their chemical properties govern the choice of the particular chemical treatment. This does not mean, however, that the reactions used on a macro-scale by organic chemists can be automatically adopted to the scale of microlitre volumes. The recent discovery of chloroformate-induced esterification of carboxylic acids is a good example of this. Over time, many derivatization methods have become more or less obsolete as their original usefulness was determined by a lack of alternative methods for the determination of minute amounts of some analytes, especially those in biological fluids. Until the discovery of immunoassay (radioimmunoassay, RIA, and enzyme immunoassay, EIA) and the development of specific and sensitive HPLC detectors, the electron-capture detector (ECD) in GC was the only way to reach picomole concentration levels. At that time, therefore, there was considerable interest in the conversion of analytes into perhalogenated products with a correspondingly high ECD response. Some of these methods or principles still persist; others do not. A comprehensive list of various chemical treatments can be found in the Handbook of Derivatives for Chromatography by Blau and Halket (see Further Reading). Some of the older useful methods and recent novel discoveries will be discussed in more detail below (see also the reviews by Husek and Wells listed in the Further Reading section).

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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