title: Extraction and derivatization of polar herbicides for GC-MS analyses.
abstract: A sample preparation procedure including a simultaneous microwave-assisted (MA) extraction and derivatization for the determination of chlorophenoxy acids in soil samples is presented. For a selective and sensitive measurement, an analytical technique such as GC coupled with MS needs to be adopted. For GC analyses, chlorophenoxy acids have to be converted into more volatile and thermally stable derivatives. Derivatization by means of microwave radiation offers new alternatives in terms of shorter derivatization time and reduces susceptibility for the formation of artefacts. Extraction and derivatization into methyl esters (ME) were performed with sulphuric acid and methanol. Due to the novelty of the simultaneous extraction and derivatization assisted by means of microwave radiation, a careful investigation and optimization of influential reaction parameters was necessary. It could be shown that the combination of sulphuric acid and methanol provides a fast sample preparation including an efficient clean up procedure. The data obtained by the described method are in good agreement with those published for the reference material. Finally, compared to conventional heating and also to the standard procedure of the EPA, the sample preparation time could be considerably shortened.
authors.affiliation: Institute of Analytical Chemistry and Radiochemistry, Graz University of Technology, Graz, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Ranz
authors.forename: Eveline
authors.initials: E
authors.lastname: Maier
authors.forename: Herbert
authors.initials: H
authors.lastname: Motter
authors.forename: Ernst
authors.initials: E
authors.lastname: Lankmayr
mesh_terms: D015085:2,4,5-Trichlorophenoxyacetic Acid / Q000032:analysis / Q000737:chemistry; D015084:2,4-Dichlorophenoxyacetic Acid / Q000032:analysis / Q000737:chemistry; D008456:2-Methyl-4-chlorophenoxyacetic Acid / Q000031:analogs & derivatives / Q000032:analysis / Q000737:chemistry; D002087:Butyrates / Q000032:analysis / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry / Q000295:instrumentation* / Q000379:methods*; D006540:Herbicides / Q000032:analysis* / Q000737:chemistry*; D008872:Microwaves; D015394:Molecular Structure; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry*; D013237:Stereoisomerism; D013696:Temperature; D013997:Time Factors
chemical_list: D002087:Butyrates; D006540:Herbicides; D012989:Soil Pollutants; D015084:2,4-Dichlorophenoxyacetic Acid; C008340:mecoprop; D015085:2,4,5-Trichlorophenoxyacetic Acid; D008456:2-Methyl-4-chlorophenoxyacetic Acid; C008418:2-methyl-4-chlorophenoxy gamma-butyric acid