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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
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).
Impact/Purpose:
The research focused on in the subtasks is the development and application of state-of the-art technologies to meet the needs of the public, Office of Water, and ORD in the area of Water Quality. Located In the subtasks are the various research projects being performed in support of this Task and more in-depth coverage of each project. Briefly, each project's objective is stated below.
Subtask 1: To integrate state-of-the-art technologies (polar organic chemical integrative samplers, advanced solid-phase extraction methodologies with liquid chromatography/electrospray/mass spectrometry) and apply them to studying the sources and fate of a select list of PPCPs. Application and improvement of analytical methodologies that can detect non-volatile, polar, water-soluble pharmaceuticals in source waters at levels that could be environmentally significant (at concentrations less than parts per billion, ppb). IAG with USGS ends in FY05. APM 20 due in FY05.
Subtask 2: Coordination of interagency research and public outreach activities for PPCPs. Participate on NSTC Health and Environment subcommittee working group on PPCPs. Web site maintenance and expansion, invited technical presentations, invited articles for peer-reviewed journals, interviews for media, responding to public inquiries.
Subtask 3: To apply state-of-the-art environmental forensic techniques to the recognition and characterization of emerging pollutants in the aquatic environment. There is a need for high sensitivity and for a powerful method of structural characterization, advanced mass spectrometric and chromatographic techniques to be employed to meet the challenge of emerging pollutants, including pharmaceuticals and personal care products, agents of sabotage, and explosives. Ongoing efforts continue to identify previously unrecognized pollutants from a range of problematic samples having importance to regional and state contacts.
Subtask 4: To provide the Agency with a set of practical analytical methods for the selective and sensitive determination of selenium species (organic, inorganic, volatile and non volatile forms) in multiple media to accurately assess and if necessary control the risk of selenium exposure to organisms. This includes development of optimal extraction, digestion, separation and detection approaches.
Subtask 5: To develop and apply an analytical method that can extract and detect synthetic musks. The extent of exposure may be determined by measuring levels of synthetic musks from their potential source (communal sewage effluent). This subtask ends in FY05 with the deliverable of APM 21. Future applications to biosolids will be covered in subtask 6.
Subtask 6: Application, and improvement, of previously in-house developed sensitive, robust, and green, methodologies regarding the use of urobilin and sterols as a possible markers of sewage contamination.
Subtask 7: Adaptation and improvement of previously developed in-house methods, for PPCPs (e.g., antibiotics and musks) to solid materials (e.g. biosolids, sediments).
Subtask 8: Study of the presence of personal care products, incombustible organic compounds from the direct-piping of small engines exhaust in Lake Tahoe, and lake deposition of airborne pollutants from industrial activity
Description:
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.