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Multiresidue Determination of Acidic Pesticides in Water By Hplc/Dad With Confirmation By Gc/MS Using Conversion to the Methyl Ester With Trimethylsilydiazomethane

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Abstract:A multiresidue pesticide methodology has been studied and results for acidics are reported here with base/neutral to follow. This work studies a literature procedure as a possible general approach to many pesticides and potentially other analytes that are considered to be liquid chromatographic candidates rather than gas chromatographic ones. The analysis of thesewage effluent of a major southwestern US city serves as an example of the application of the methodology to a real sample. Recovery studies were also conducted to validate the proposed extraction step. A gradient elution program was followed for the high performance liquid chromatography leading to a general approach for acidics. Confirmation of identity was by EI GC/MS after conversion of the acids to the methyl ester (or other appropriate methylation) by means of trimethylsilyldiazomethane. The 3,4-dichlorophenoxyacetic acid was used as an internal standard to monitor the reaction and PCB #19 was used for the quantitation internal standard. Although others have reported similar analyses of acids, conversion to the methyl ester was by means of diazomethane itself rather than by the more convenient and safer trimethylsilyldiazomethane. Thus, the present paper supports the use of trimethylsilyldiazomethane with all of these acids (trimethylsilyldiazomethane has been used in environmental work with some phenoxyacetic acid herbicides) and further supports the usefulness of this reagent as a potential replacement for diazomethane. The HPLC approach here could also serve as the separation basis for an LC/MS solution to confirmation of identity as well as quantitation.
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Citation:Moy, T., and W. C. Brumley. Multiresidue Determination of Acidic Pesticides in Water By Hplc/Dad With Confirmation By Gc/MS Using Conversion to the Methyl Ester With Trimethylsilydiazomethane. JOURNAL OF CHROMATOGRAPHY 41(7):343-349, (2003).
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Contact: Chris Siebert - (702) 798-2234 or siebert.christopher@epa.gov
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Division: Environmental Sciences Division
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Branch: Environmental Chemistry Branch
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Product Type: Journal
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Published: 08/14/2003
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Related Entries:
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Bullet Item Addressing Emerging Issues in Water Quality Through Environmental Chemistry
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