Low-Cost Technique to Monitor Organophosphate Pesticides in Copeland Creek

Project Description: Organophosphorus pesticides are a commonly occurring environmental toxin that is found in agricultural pesticides. These chemicals are similar in composition to Sarin nerve gass and can kill or reproductive damage in fish and amphibians. Pesticide mixes can be more toxic than single pesticides alone.

Solid Phase Microextraction (SPME) is a relatively new technique that is used to separate organic compounds from water so that they can be analyzed by gas chromatography/mass spectroscopy. We refined this technique to target organophosphate detection in samples from Copeland Creek. We are currently working on quantifying the organic pesticides.

Duration: Fall 2013 - Spring 2014

Type of Educational Activities: Independent research

Project Faculty: Mark Perri (Chemistry)


  • SCWA
  • Center for Environmental Inquiry
  • SSU Research, Scholarship and Creative Activity Program (RSCAP)

Participating Courses:

  • Chemistry 494 Independent Research - 3 students

Gas chromatography–mass spectrometry (GC-MS) combines gas-liquid chromatography and mass spectrometry to identify different substances within aquatic samples. Gas chromatography uses a capillary column to separate the molecules and the mass spectrometer then detects ionized molecules based on their different mass-to-charge ratios. Peaks in the resulting spectra are then compared to signatures of known substances to identify the contaminants. Contaminant concentration can be estimated by comparing peak height to solutions with known concentrations of the contaminant.Water samples were collected on July 29, 2013 from 3 sites on Copeland Creek: Commerce Road, Santa Alicia USGS Stream Gauge, and SSU Outfall.

Polar organic compounds were extracted using solid phase microfiber extraction (SPME).

Compounds were desorbed into the injector of a gas chromatograph. As the compounds exit from the chromatograph they enter a mass spectrometer which analyzes the molecular weight of the compound and fragments of the compound that form in the detector. For more details, see Diamond et al. 2104, and Diamond 2014 below in "Resulting Data & Reports."

Field collection and laboratory techniques were undertaken by SSU students under the guidance of Dr. Mark Perri.

Results Summary: The following organic compounds were detected in the Copeland Creek samples: trichlorormethane, styrene, 2-ethenyl pyridine, tetraphenyl hydrazine, benzophenone, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate. (Note: In the accompanying diagram, acetophenone is listed as a contaminant. The exceedingly low concentrations made identification uncertain and we have since removed it from the confirmed list of contaminants.) All compounds were in very low concentrations except for the phthalates. Phthalates were likely present because the samples were collected in plastic containers. Future sampling will avoid the use of plastic containers. Estimating the concentration of organophosphate pesticides using deuterated internal standards is underway.

Data (see data disclaimer)


Scientific Papers

  • Atkinson, R. and J. Arey (1998). "Atmospheric Chemistry of Biogenic Organic Compounds." Accounts of Chemical Research 31(9): 574-583.
  • Brilli, F., et al. (2012). "Qualitative and Quantitative Characterization of Volatile Organic Compound Emissions from Cut Grass." Environmental Science & Technology 46(7): 3859-3865.
  • Custer, T. and G. Schade (2007). "Methanol and acetaldehyde fluxes over ryegrass." Tellus B 59(4): 673-684.
  • Van Opstaele, F., et al. (2012). "Characterization of Novel Varietal Floral Hop Aromas by Headspace Solid Phase Microextraction and Gas Chromatography–Mass Spectrometry/Olfactometry." Journal of Agricultural and Food Chemistry 60(50): 12270-12281.
  • Scholz, N. L., et al. (2012). "A Perspective on Modern Pesticides, Pelagic Fish Declines, and Unknown Ecological Resilience in Highly Managed Ecosystems." Bioscience 62(4): 428-434.
  • Laetz, C. A., et al. (2013). "Interactive Neurobehavioral Toxicity of Diazinon, Malathion, and Ethoprop to Juvenile Coho Salmon." Environmental Science & Technology 47(6): 2925-2931.