Authors: Martyna Rompa Ewa Kremer Bogdan Zygmunt
Publish Date: 2003/08/06
Volume: 377, Issue: 4, Pages: 590-599
Abstract
This paper reviews derivatisation processes applied in chromatographic determination of acidic herbicides with carboxyl and phenol groups mainly in aqueous environmental samples The discussion focuses on the basic derivatisation reactions used to convert herbicides to derivatives to make them analysable by gas chromatography and possibly to reduce detection limits and/or increase extraction recovery from aqueous samples The reactions are transesterification esterification silylation alkylation and extractive and pyrolytic alkylation The reagents used to conduct the reactions are numerous Diazomethane is a very efficient methylation reagent but explosive and toxic Methyl iodide also ensures rapid and efficient methylation Benzyl bromide can be used directly in water but derivatisation yield is low and reproducibility is poor Butyl chloroformate and dimethyl sulfite can also be used for derivatisation in water and acetic anhydride can be used for insitu derivatisation of phenolic herbicides For increasing selectivity of GC detection pentafluorobenzyl bromide for ECD and 2cyanethyldimethyldiethylaminosilane for NPD have been applied Very characteristic ions are produced in mass spectra if silyl groups are introduced eg by using bistrimethylsilyltrifluoroacetamide Tetramethylammonium trimethylphenylammonium tetraalkylammonium and trimethylsulfonium hydroxides and salts can by used for derivatisation at elevated temperature in the GC injection port Extractive alkylation is relatively efficient if tetraalkylammonium salts with long chain alkyl groups are used
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