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Reduction of Reduction of Mesotrione in Mesotrione in Aquifers and Aquifers and Surface Waters Surface Waters Amber Grandprey Amber Grandprey Chem 4101 Chem 4101 10 Dec 2010 10 Dec 2010
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Reduction of Mesotrione in Aquifers and Surface Waters Amber Grandprey Chem 4101 10 Dec 2010.

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Page 1: Reduction of Mesotrione in Aquifers and Surface Waters Amber Grandprey Chem 4101 10 Dec 2010.

Reduction of Mesotrione Reduction of Mesotrione in Aquifers and Surface in Aquifers and Surface

WatersWaters

Amber GrandpreyAmber Grandprey

Chem 4101Chem 4101

10 Dec 201010 Dec 2010

Page 2: Reduction of Mesotrione in Aquifers and Surface Waters Amber Grandprey Chem 4101 10 Dec 2010.

Background on MesotrioneBackground on Mesotrione Mesotrione is part of the Mesotrione is part of the

triketone class of pesticides.triketone class of pesticides. Approximately 150,000 lbs Approximately 150,000 lbs

of mesotrione has been sold of mesotrione has been sold over the past six years in over the past six years in Minnesota alone.Minnesota alone.

Because of its widespread Because of its widespread use, mesotrione finds its use, mesotrione finds its way into aquifers and way into aquifers and surface waters, which can surface waters, which can have effects on families as have effects on families as well as industrial and well as industrial and commercial practices which commercial practices which require groundwater.require groundwater.

The reaction is mediated by iron The reaction is mediated by iron mineral surfaces found naturally in mineral surfaces found naturally in aquifers and surface waters.aquifers and surface waters.The reduction of a similar The reduction of a similar compound, trifluralin, has been compound, trifluralin, has been studied by a professor here at the studied by a professor here at the University of Minnesota, Bill Arnold.University of Minnesota, Bill Arnold.

Page 3: Reduction of Mesotrione in Aquifers and Surface Waters Amber Grandprey Chem 4101 10 Dec 2010.

Degradation of MesotrioneDegradation of Mesotrione

Mesotrione is known to degrade into two compounds: Mesotrione is known to degrade into two compounds: MNBA and AMBA.MNBA and AMBA.

The kinetics and effects on the sediment of the The kinetics and effects on the sediment of the environment as an effect of this degradation are still environment as an effect of this degradation are still unknown.unknown.

Page 4: Reduction of Mesotrione in Aquifers and Surface Waters Amber Grandprey Chem 4101 10 Dec 2010.

HypothesisHypothesisHypothesisHypothesis

The degradation of mesotrione causes changes in the The degradation of mesotrione causes changes in the sediment mineralogy of aquifers and surface water. sediment mineralogy of aquifers and surface water. These changes are in response to continual exposure to These changes are in response to continual exposure to oxidized contaminants in the water system, which allows oxidized contaminants in the water system, which allows for the development of pseudo-steady state reactivity.for the development of pseudo-steady state reactivity.

Significance of Solving ProblemSignificance of Solving Problem Quantifying the pseudo-steady state reactivity will open Quantifying the pseudo-steady state reactivity will open

the door to determining the potential for long-term the door to determining the potential for long-term attenuation of mesotrione in the environment.attenuation of mesotrione in the environment.

Page 5: Reduction of Mesotrione in Aquifers and Surface Waters Amber Grandprey Chem 4101 10 Dec 2010.

Experimental SetupExperimental Setup Single injection batch reactions will be used to simulate Single injection batch reactions will be used to simulate

natural conditions in aquifers and surface watersnatural conditions in aquifers and surface waters A buffer solution of pH 7.5 will be used with all batch A buffer solution of pH 7.5 will be used with all batch

reactionsreactions MOPS (3-(N-morpholino)propanesulfonic acid) or MES (2-(N-MOPS (3-(N-morpholino)propanesulfonic acid) or MES (2-(N-

morpholino)ethanesulfonic acid) buffers are the most appropriate morpholino)ethanesulfonic acid) buffers are the most appropriate for the experimentsfor the experiments

After addition of a reducing compound (mainly Fe(II)) and After addition of a reducing compound (mainly Fe(II)) and goethite or goethite sand to the buffer solution, the reactor goethite or goethite sand to the buffer solution, the reactor will be set on a rotator at approx. 50 rpm to equilibrate for will be set on a rotator at approx. 50 rpm to equilibrate for at least 12 hoursat least 12 hours

Mesotrione can then be spiked into the reactor and Mesotrione can then be spiked into the reactor and samples taken at specific time intervals. These samples samples taken at specific time intervals. These samples can then be analyzed via HPLC-UV/Vis for degradation.can then be analyzed via HPLC-UV/Vis for degradation.

Page 6: Reduction of Mesotrione in Aquifers and Surface Waters Amber Grandprey Chem 4101 10 Dec 2010.

Sample PreparationSample Preparation All reactions will be run in 124 mL serum bottles.All reactions will be run in 124 mL serum bottles. Each serum bottle will contain the following (assuming Each serum bottle will contain the following (assuming

reaction is run to test Fe(II) kinetics):reaction is run to test Fe(II) kinetics): 5 mg goethite or 600 mg of goethite5 mg goethite or 600 mg of goethite 0.124 mL 1.1 M FeCl0.124 mL 1.1 M FeCl22

Fill serum bottle to the top with de-oxygenated pH 7.5 MOPS Fill serum bottle to the top with de-oxygenated pH 7.5 MOPS or MES buffer, cap with a crimp cap, and set to equilibrate.or MES buffer, cap with a crimp cap, and set to equilibrate.

After equilibration, remove crimp cap, spike in enough After equilibration, remove crimp cap, spike in enough mesotrione to bring concentration to 5 mesotrione to bring concentration to 5 μμM (0.2 mg), cover with M (0.2 mg), cover with aluminum foil, and begin sampling.aluminum foil, and begin sampling.

Samples must be filtered with 0.2 Samples must be filtered with 0.2 μμm nylon filter and added m nylon filter and added to 0.5 to 0.5 μμL hydroxylamine hydrochloride before HPLC analysis L hydroxylamine hydrochloride before HPLC analysis to prevent the oxidation of Fe(II)to prevent the oxidation of Fe(II)

Page 7: Reduction of Mesotrione in Aquifers and Surface Waters Amber Grandprey Chem 4101 10 Dec 2010.

InstrumentationInstrumentation

Degradation Kinetics Technique: HPLC-Degradation Kinetics Technique: HPLC-UV/Vis AbsorptionUV/Vis Absorption Detection Wavelengths: 200 nm for Detection Wavelengths: 200 nm for

mesotrione, 562 nm for Fe(II)mesotrione, 562 nm for Fe(II)

Changes in Sediment Mineralogy: Changes in Sediment Mineralogy: Transmission Electron MicroscopyTransmission Electron Microscopy

Page 8: Reduction of Mesotrione in Aquifers and Surface Waters Amber Grandprey Chem 4101 10 Dec 2010.

HPLC-UV/VisHPLC-UV/Vis

HP 1090 photodiode HP 1090 photodiode array detectorarray detector

Column: Reverse phase Column: Reverse phase stainless steel, 250 x 4.6 stainless steel, 250 x 4.6 mm, C18, 5 mm, C18, 5 μμM particles M particles (ex. Inertsil ODS-3V)(ex. Inertsil ODS-3V)

Mobile Phase: 40% Mobile Phase: 40% MeOH, 60% water MeOH, 60% water acidifed to pH 3 using acidifed to pH 3 using phosphoric acidphosphoric acid

Flow rate: 1 mL/minFlow rate: 1 mL/min

LOD: 0.5 LOD: 0.5 μμg/Lg/L Linear range: 10Linear range: 1044

Adequate sensitivityAdequate sensitivityGood reproducibilityGood reproducibility

Page 9: Reduction of Mesotrione in Aquifers and Surface Waters Amber Grandprey Chem 4101 10 Dec 2010.

Transmission Electron Microscopy Transmission Electron Microscopy (TEM)(TEM)

Works on same basic Works on same basic principles as a light principles as a light microscopemicroscope

Shoots electrons through Shoots electrons through a thin sample onto an a thin sample onto an electromagnetic lense, electromagnetic lense, which magnifies and which magnifies and focuses the image onto focuses the image onto an imaging devicean imaging device

High resolution capability High resolution capability allows observation of allows observation of objects to the order of a objects to the order of a few angstromfew angstrom

Suitable instrument for this Suitable instrument for this type of analysis is an HRTEM type of analysis is an HRTEM equipped with a charge-couple equipped with a charge-couple device cameradevice camera Specific model to use: FEI Specific model to use: FEI Techni T12Techni T12

Page 10: Reduction of Mesotrione in Aquifers and Surface Waters Amber Grandprey Chem 4101 10 Dec 2010.

Figures of MeritFigures of Merit

TechniqueTechnique ProsPros ConsCons

HPLC-HPLC-UV/VisUV/Vis

Cost efficient, Fast Cost efficient, Fast analysis, analysis,

Nondestructive, Nondestructive, Reliable, Reliable,

ReproducibilityReproducibility

S/N can be high, S/N can be high, High pressure High pressure

used in used in experiment experiment (~155 Pa)(~155 Pa)

TEMTEM

High resolution, High resolution, Several imaging Several imaging

methods availablemethods available

Cost, Slow, Cost, Slow, ReproducibilityReproducibility

Page 11: Reduction of Mesotrione in Aquifers and Surface Waters Amber Grandprey Chem 4101 10 Dec 2010.

ConclusionsConclusions

By determining the degradation kinetics of By determining the degradation kinetics of mesotrione and quantifying changes in mesotrione and quantifying changes in mineralogy of the sediment due to this mineralogy of the sediment due to this degradation, the possibility of long-term degradation, the possibility of long-term attenuation of mesotrione can be assessed.attenuation of mesotrione can be assessed.

The kinetics can be determined using HPLC-The kinetics can be determined using HPLC-UV/Vis techniques and the changes in UV/Vis techniques and the changes in mineralogy can be quantified using TEM.mineralogy can be quantified using TEM.

Page 12: Reduction of Mesotrione in Aquifers and Surface Waters Amber Grandprey Chem 4101 10 Dec 2010.

ReferencesReferences Minnesota Department of Agriculture, Minnesota Department of Agriculture,

http://www.mda.state.mn.us/chemicals/pesticides/useanhttp://www.mda.state.mn.us/chemicals/pesticides/useandsales.aspxdsales.aspx, Accessed: Sept. 21, 2010., Accessed: Sept. 21, 2010.

Ter Halle,A.; Richard, C. Ter Halle,A.; Richard, C. Environ. Sci. Technol.Environ. Sci. Technol. 2006,2006, 40,40, 3842-3847 3842-3847

Chun, C. L.; Penn, R. Lee.; Arnold, W. A. Chun, C. L.; Penn, R. Lee.; Arnold, W. A. Environ. Sci. Environ. Sci. Technol.Technol. 2006,2006, 40,40, 3299-3304 3299-3304

Klupinski, T. P. Klupinski, T. P. Environ. Sci. Technol.Environ. Sci. Technol. 2003,2003, 37,37, 1311- 1311-13181318

Nobel Foundation: The Transmission Electron Nobel Foundation: The Transmission Electron Microscope. Microscope. http://nobelprize.org/educational/physics/microscopes/tehttp://nobelprize.org/educational/physics/microscopes/tem/index.html (Accessed Dec 7, 2010).m/index.html (Accessed Dec 7, 2010).