http://www.newton.dep.anl.gov/askasci/mole00/mole00209.htm
This is a special case of the analysis of any trace organic compound.
The procedure for the isolation and identification of trace organic compoundsgenerally involves these steps:1. Concentration, 2. Separation & Classification (acid, base, or neutral),3. Identification (what substance), and 4. Quantification (how much).
The concentration / separation is accomplished by one of three methods:[a.] liquid chromatography, [b.] selective absorption on macroreticularresins + selective elution (this is a special type of liquidchromatography), [c.] vapor phase chromatography.
The classification step, where needed, is accomplished by selective elutionwith an acid, a base or a neutral eluent. This step is also sometimes useddirectly in conjunction with vapor phase chromatography which separates thecompounds according to volatility and absorption on a surface-treatedabsorbant substrate.
The identification / quantification can be accomplished by any appropriate organic analytical technique; however, the most direct method is highresolution mass spectrometry. High resolution mass spectrometry yields aprecise molecular mass of the parent compound, and the precise masses ofcracking fragments often allows the assignment of a molecular structure.This data often permits assignment of a molecular structure, since theseinstruments search enormous libraries of the mass spectra of knownsubstances.
The structure assignment can be confirmed by synthesizing thecandidate compounds and comparing their mass spectra, if necessary, butoften it is not necessary.In labs set up to do this type of analysis, the concentration /separationsteps are frequently connected directly to the front end of the massspectrometer so that there is not intermediate handling of the variouscompounds.The characterization of trace organic compounds is chemical technology atits max.
This is a special case of the analysis of any trace organic compound.
The procedure for the isolation and identification of trace organic compoundsgenerally involves these steps:1. Concentration, 2. Separation & Classification (acid, base, or neutral),3. Identification (what substance), and 4. Quantification (how much).
The concentration / separation is accomplished by one of three methods:[a.] liquid chromatography, [b.] selective absorption on macroreticularresins + selective elution (this is a special type of liquidchromatography), [c.] vapor phase chromatography.
The classification step, where needed, is accomplished by selective elutionwith an acid, a base or a neutral eluent. This step is also sometimes useddirectly in conjunction with vapor phase chromatography which separates thecompounds according to volatility and absorption on a surface-treatedabsorbant substrate.
The identification / quantification can be accomplished by any appropriate organic analytical technique; however, the most direct method is highresolution mass spectrometry. High resolution mass spectrometry yields aprecise molecular mass of the parent compound, and the precise masses ofcracking fragments often allows the assignment of a molecular structure.This data often permits assignment of a molecular structure, since theseinstruments search enormous libraries of the mass spectra of knownsubstances.
The structure assignment can be confirmed by synthesizing thecandidate compounds and comparing their mass spectra, if necessary, butoften it is not necessary.In labs set up to do this type of analysis, the concentration /separationsteps are frequently connected directly to the front end of the massspectrometer so that there is not intermediate handling of the variouscompounds.The characterization of trace organic compounds is chemical technology atits max.
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