Volatile organic compounds classification

Organic compounds such as the chlorinated solvents also include a wide range of compounds and do not easily fit into the structural classification as described for petroleum hydrocarbons. Chlorinated hydrocarbons are commonly discussed in terms of their relative density (i.e., LNAPL or DNAPL) or degree of halogenation and degree of volatility (i.e., volatile, semi-volatile). 

The ANN approach has also been applied to compound classification. For example, Drefahl [48] has discussed the ANN approach to discriminate chlorinated organics with respect to their volatility from aqueous solutions. Varmuza [49] has described ANN classification as a standard method in pattern recognition and provides references to its use in spectra interpretation. 

Such an approach has been used to develop customized noses (specific arrays of polymers) for classification of beers, detection and identification of microorganisms, olive oil characterization, and detection/classification of BTEX compounds (volatile organic carbons). 

As long as our familiarity with organic bodies was merely superficial and limited itself primarily to external properties, while transformations and mutual relations remained almost entirely unknown, the classifications of organic compounds, considered firom the standpoint of chemistry, could not be natural. At that time, bodies were grouped according to their origin, color, consistency, etc., divided into volatile oils, resins, dyestuffs, etc. A closer, but not yet complete famdiarity with the chemical properties of a part of the organic compounds led to the distinction between acids, alkalis, and indifferent bodies. 

Lipoids as a type are non-saponifiable, although some of the sterols may occur as esters with aliphatic acids. A systematic classification of the lipoids is unsatisfactory, since the only common property of these compounds is the physical one of solubility in certain organic solvents. Examples of biological lipoids occur in the essential or volatile oils of plants and the fat-soluble pigments (lipochromes) of plants and animals. In addition, some of the vitamins and the hormones belong to the lipoid type, in that they are fat-soluble. 

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