Grantee Research Project Results
Final Report: Ion-Pair/Supercritical Fluid Extraction and Derivatization for Polar Organic Pollutant Analysis
EPA Grant Number: R821195Title: Ion-Pair/Supercritical Fluid Extraction and Derivatization for Polar Organic Pollutant Analysis
Investigators: Field, Jennifer
Institution: Oregon State University
EPA Project Officer: Packard, Benjamin H
Project Period: September 1, 1995 through September 1, 1998
Project Amount: $392,272
RFA: Exploratory Research - Chemistry and Physics of Water (1995) RFA Text | Recipients Lists
Research Category: Water , Land and Waste Management , Safer Chemicals
Objective:
The development of new techniques for coupling sample isolation, concentration, and derivatization for the analysis of polar organic pollutants was proposed. Alternative quantitative analytical methods were sought because conventional methods for polar compound analysis typically are time-consuming, multi-step, and involve hazardous reagents and procedures. New methods were developed that eliminated the use of diazomethane, a toxic and a potentiai explosion hazard, and that reduced the volume of solvent consumed during sample preparation and analysis. In the case of solid samples, preparative sample isolation, concentration, and derivatization steps were coupled by combining supercritical fluid and/sr subcritical (hot) water extraction with solid phase extraction. Solid phase extraction disks were used to isolate nonpolar and acid analytes from soil or sludge extracts as well as water samples. A novel "in-vial" elution technique, which uses a minimal volume of solvent (e.g., 1 mL), was used to elute analytes directly into small 2 mL autosampler vials. In the case of acid analytes, the acids were simultaneously eluted from the disks and derivatized to their methyl or ethyl esters. With this approach, the time required to derivatize the acid anal,vtes was significantly reduced compared to traditional esterification procedures.The general goal of this project is to develop, validate, and demonstrate new methodologies for extracting and derivatizing polar organic chemicals in aqueous and solid matrices. In pursuit of this goal the following project objectives are outlined:
- To develop alternative methods for determining polar (acidic) contaminants in solid environmental matrices that couple supercritical fluid or subcritical (hot) water extraction together with derivatization reactions that minimize or eliminate organic solvents for the extraction and derivatization.
- To develop alternative extraction methods for polar organic contaminants in aqueous environmental matrices that couple preparative steps and minimize organic solvent usage.
- To validate and demonstrate the alternative methodologies that couple the preparative steps such as extraction and derivatization using actual field samples including ground water, surface water, soils/sediments, and sewage sludges.
Summary/Accomplishments (Outputs/Outcomes):
In order to replace conventional extraction methods that utilize large volumes of chlorinated and nonchlorinated solvents, alternative extraction strategies were explored that required nontoxic, inexpensive, and low volumes of nonchlorinated extraction solvents. The focus of methods development for environmental solids such as soils sediments, and sludges was upon the use of subcritical (hot) water and supercritical carbon dioxide. In the case of water samples, the focus was on the complete elimination of chlorinated solvents and a reduction in the total volume of solvent used. Reductions in analysis time were realized by using flexible solid phase extraction (Empore) disks to concentrate analytes extracted from solid and aqueous samples. A novel "in-vial" elution approach was used for all methods to elute the analytes from the disk by placing the disk directly in small 2 rnL autosampler vials with a small volume (e.g., 1.5 rnL) of nonchlorinated organic solvent. Nonpolar analytes were desorbed from the disk and analyzed directly. In the case of acid analytes, elution from the disk and derivatization were accomplished simultaneously with the addition of methyl or ethyl iodide since the disks act as alkylation reaction catalysts. All methods were developed and optimized using solid and aqueous samples containing native or naturally-occurring analytes of interest. Spike and recovery experiments with solids were restricted to determining initial solvent conditions and analyte collection efficiency. Once the extraction and derivatization methods were optimized, the methods were demonstrated on a number of soil, sludge, and groundwater samples. The four methods developed for this project are briefly described below.Dacthal and its mono- and diacid metabolites were sequentially extracted from soils by first performing a supercritical carbon dioxide extraction to recover Dacthal followed by a subcritical (hot) water extraction step to recover metabolites (3). Dacthal was recovered from soil in 15 min by supercritical carbon dioxide at 150 ?C and 400 bar. The mono- and diacid metabolites were extracted from soil in 10 min under the subcritical water conditions of 50 ?C and 200 bar. The metabolites were trapped ir'-situ on a strong anion exchange (SAX) disk placed over the exit Dit of the extraction cell. Metabolites are combined together with Dacthal by placing the disk into the GC autosampler vial containing the SFE extract. The metabolites then are simultaneously eluted from the disk and derivatized to their ethyl esters by adding 100 I1L ethyl iodide and heating the vial at 100 ?C for 1 hr. Using this approach only a single sample is analyzed, and because the disk-catalyzed alkylation reaction does not transesterify Dacthal, the speciation of Dacthal is maintained. In addition, no sample clean-up steps are required, the use of diazomethane for derivatization is avoided, and the method consumes a total of 5 mL of nonchlorinated organic solvent.
Subcritical (hot) water with ethanol as modifier was used to extract nonylphenol polyethoxy carboxylates containing 1-4 ethoxy groups from sludge samples (2). Quantitative recovery of native NPECs from sludge was accomplished by extracting 0.25 g samples for 20 min with 30 % (v/v) ethanol in water at 75 ?C and 150 bar. NPECs in the water/ethanol extract were concentrated by a strong anion exchange (SAX) Empore disk. The NPECs were simultaneously eluted and derivatized to their methyl esters in an autosampler vial. NPEC concentrations ranged from 27 to 113 with NP2E(: as the most abundant oligomer. The ratio of ortho to para isomers were 1 for NP2EC and NP3EC in the two samples containing anaerobically-digested sewage sludge. The relatively higher percentage of ortho isomers in the samples containing anaerobically-digested sludge suggests that the sludge digestion process results in the enrichment of ortho isomers relative to para isomers since commercial mixtures of nonylphenol polyethoxylates contain only a minor amount (<10%) of ortho isomers. In contrast, the secondary clarifier sludge from the paper mill, which received only aerobic treatment, contained only para NPEC isomers.
A simple and rapid method was developed to determine concentrations of diuron (N'-(3,4-dichlorophenyl)-N,N-dimethylurea) and three of its major metabolites, DCPMU (N'-(3,4-dichlorophenyl)-N-methylurea), DCPU (3,4-dichlorophenylurea), and DCA (3,4-dichloroaniline) in ground water and surface water (4). The analytical method utilizes a 25 mm C18 Empore disk to quantitatively determine diuron and its metabolites in 100 mL water samples. All analytes are eluted by placing the disk directly into a 2 mL autosampler vial in 1.5 rnL of methanol/acetonitrile (50/50) for analysis by HPLC with W detection. Recoveries from spiked field sample matrices were 98.8+1.6%, 98.1+ 4.5%, 98.213.6%, and 77.8+4.5% for diuron, DCPMU, DCPU, and DCA, respectively. The method precision, indicated by the relative standard deviation, was typically + 5%. The method detection and quantitation limits are 0.5 1lg/L and 1 ~g/L for all analytes except dichloroaniline (1.0 1lg/L and 2.0 1lg/L, respectively). The concentrations of diuron and its metabolites determined in surface water and ground water samples collected from a field study site were determined.
Perfluorinated surfactants are used in aqueous film forming foam (AFFF) formulations, which are used to extinguish hydrocarbon-fuel fires. Virtually nothing is known about the occurrence of perfluorinated surfactants in the environment, in particular, at fire-training areas and emergency response sites where AFFF enters groundwater without prior treatment. Strong anion exchange Empore disks were used to extract perfluorocarboxylic acids from groundwater collected from fire training facilities located on Naval Air Station Fallon, NV and Tyndall Air Force Base, FL (1). The acids were simultaneously eluted from the disks and derivatized to their methyl esters for direct analysis by GC/MS. Perfluorocarboxylic acids containing 6-8 carbons were detected in groundwater collected Dom the two field sites with total concentrations ranging from 124 to 7,086 ,ug/L. To the best of our knowledge, this is the first definitive identification of perfluorocarboxylic acids in groundwater. While the source of the perfluorocarboxylic acids identified in groundwater near inactive fire training facilities is unknown, their detection after 10 years of inactivity indicates their potential utility as markers for delineating groundwater impacted by fire fighting activities.
Conclusions:
Alternative extraction methods were developed for the quantitative determination of polar contaminants in solid and aqueous environmental matrices. The developed extraction methods are rapid, simple, inexpensive, and require the use of environmentally-friendly extraction solvents, such as carbon dioxide, water, and ethanol.The methods are faster compared to conventional methods because the steps of extraction, analyte elution, and derivatization were combined together through the use of flexible Empore disks. Small volumes (5- 20 rnL) of nonchlorinated solvents such as acetonitrile, methanol, and acetone were used to carry out the steps of Empore disk preparation, elution, and analyte derivatization. In all cases where derivatization was required, diazomethane, a potentially explosive and carcinogenic conventional derivatization reagent, was replaced by Empore-disk catalyzed alkylation reactions.
Journal Articles on this Report : 5 Displayed | Download in RIS Format
Other project views: | All 13 publications | 5 publications in selected types | All 5 journal articles |
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Field JA, Reed RL, Sawyer TE, Martinez M. Diuron and its metabolites in surface water and ground water by solid phase extraction and in-vial elution. Journal of Agricultural and Food Chemistry 1997;45(10):3897-3902. |
R821195 (1998) R821195 (Final) |
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Field JA. Coupling chemical derivatization reactions with supercritical fluid extraction. Journal of Chromatography A 1997;785(1-2):239-249. |
R821195 (1998) R821195 (Final) |
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Field JA, Monohan K, Reed R. Coupling supercritical CO2 and subcritical (hot) water for the determination of Dacthal and its acid metabolites in soil. Analytical Chemistry 1998;70(9):1956-1962. |
R821195 (1998) R821195 (Final) |
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Moody CA, Field JA. Determination of perfluorocarboxylates in groundwater impacted by fire-fighting activity. Environmental Science & Technology 1999;33(16):2800-2806. |
R821195 (1998) R821195 (Final) |
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Field JA, Reed RL. Subcritical (hot) water/ethanol extraction of nonylphenol polyethoxy carboxylates from industrial and municipal sludges. Environmental Science & Technology 1999;33(16):2782-2787. |
R821195 (1998) R821195 (Final) |
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Supplemental Keywords:
Scientific Discipline, Waste, Water, Contaminated Sediments, Environmental Chemistry, Physics, Chemistry, Engineering, Chemistry, & Physics, solvent waste, sediment toxicity, contaminated sediment, alternative extraction, polar organic compounds, carbon dioxide, soil contaminants, super critical fluid extraction, ion pair, coupling derivatization reactionsProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.