Ben Diamond. Sonoma State University

Transcription

1 Method Development for the Monitoring of Organophosphate Pesticides in Copeland Creek and Local water ways via Solid Phase Micro Extraction coupled with Gas Chromatography Mass Spectrometry Ben Diamond Sonoma State University

2 Why Pesticides? Copeland Creek is part of the Russian River Watershed Pesticides can negatively impact people and the environment 1 Organophosphorus pesticides similar to Sarin a nerve gas 1. Relyea, R. A., A cocktail of contaminants: how mixtures of pesticides at low concentrations affect aquatic communities. Oecologia 2009, 159 (2), North Coast Integrated Regional Water Management Plan. (2/9/14)

3 Pesticides of Interest

4 Solid Phase Micro Extraction(SPME) Adsorption based sample extraction Solventless Fast Simple Sigma-Aldrich. (accessed Feb/9/14)

5 SPME Fibers A coated fused silica or steel wire Multiple Coatings - Graphene [right], Polyacrylate, metal alloys and other polymers Chen, J.; Zou, J.; Zeng, J.; Song, X.; Ji, J.; Wang, Y.; Ha, J.; Chen, X., Preparation and evaluation of graphene-coated solid-phase microextraction fiber. 2010, 678 (1),

6 SPME Sample Extraction Scheme Fiber Retracted Fiber Retracted Analyte Adsorbed Fiber Extended Desorption

7 Gas Chromatography Mass Spectrometry Volatilizes sample Sample compounds separated by a column housed in an a variable temperature oven Carried through by an inert gas Compounds ionized as they come off the Results in ionized fragments of the molecule Ions are separated and detected based on their mass to charge ratio (m/z)

8 GCMS Schematic Diagram Sample Inlet

9 Sample Inlet Desorbs the sample from the SPME fiber

10 Oven Variable Temp. Separates Compounds by volatility Column Fused Silica Separates Analyte by polarity Crossbond by Restek

11 Quadrupole Mass Spectrometer Four metal rods, two AC, two DC Ions separated by m/z

12 Total Ion Chromatogram (TIC) Mass Spectrum

13 Processing Total Ion Chromatograms Chromatograms deconvoluted using Automated Mass Spectral Deconvolution and Identification System (AMDIS)

14 Poor Match

15 Good Match

16 1. Sulfotep: min 2. Diazinon: min 3. Malathion: min 4. Fenthion: min

17 SPME-GCMS Method Optimization SPME Stir Rate, ph, salinity GCMS Affect the time it takes to reach equilibrium between the fiber and the matrix Inlet temperature, split/splitless mode, oven temperature, carrier gas flow rate Affect retention time

18 Quantification With GCMS Use an Internal Standard Maintain a constant concentration of Internal standard while varying concentration of analyte Compares peak area to concentration

19 Pesticides of Interest

20 Internal Standard Method 0.5 µg/l Analyte Mix 1µg/L Fenthion 2 µg/l Analyte Mix 1µg/L Fenthion 10 µg/l Analyte Mix 1µg/L Fenthion

21 Internal Standard Results 12 Response Factor (F) vs. Concentration 10 8 F 6 4 Sulfotep Diazinon Malathion Concentration (µg/l)

22 Response Factor 1.8 Sulfotep as Analyte, Diazinon as Internal Standard Diazinon as Analyte, Sulfotep Internal Standard Response Factor [Concentration] (µg/l)

23 Real World Sample Procedure No Injection Blank Fiber Blank Milli-Q Water Blank Identify peaks Overlay Sample TIC with Blank TIC s Sample spiked with Internal Standard * Filtered if necessary

24 Relative Abundance Overlaid TIC Time (min) Fiber Blank Milli-Q Blank Sample

25 Preserve Water Sample File ("4-WATERSAMPLE-B.D") Relative Abundance 1.4x x x x x x x x a a. Trichloromethane b. Styrene c. 2-ethenylpyridine d. Acetophenone e. Diethylphtalate f. Tetraphenylhydrazine g. Benzophenone h. Di-Isobutylphtalate i. Dibutylphtalate b c d Time (min) Path ("D: ") e f g h i

26 Conclusion Developed a valid qualitative SPME/GCMS Standard Operating Procedure for real world sample analysis Developing quantitative SPME/GCMS method to monitor Organophosphorous pesticides

27 Future Work Continue Optimizing SPME-GCMS method SPME Revisit ph and Salinity GCMS Optimize method for new column Continue Internal Standard runs Deuterated Diazinon Identify and minimize potential sources of contamination

28 Acknowledgements Dr. Perri Dr. Marshall Dr. Claudia Luke Christy Gorman Michael Häggmark Shelby Triplitt Erin Ballantyne Sonoma State Chemistry Department Funding: WATERS Collaborative and SSU RSCAP