Articles | Volume 10, issue 6
https://doi.org/10.5194/amt-10-2117-2017
https://doi.org/10.5194/amt-10-2117-2017
Research article
 | 
08 Jun 2017
Research article |  | 08 Jun 2017

Gas-phase pesticide measurement using iodide ionization time-of-flight mass spectrometry

Trey Murschell, S. Ryan Fulgham, and Delphine K. Farmer

Abstract. Volatilization and subsequent processing in the atmosphere are an important environmental pathway for the transport and chemical fate of pesticides. However, these processes remain a particularly poorly understood component of pesticide lifecycles due to analytical challenges in measuring pesticides in the atmosphere. Most pesticide measurements require long (hours to days) sampling times coupled with offline analysis, inhibiting observation of meteorologically driven events or investigation of rapid oxidation chemistry. Here, we present chemical ionization time-of-flight mass spectrometry with iodide reagent ions as a fast and sensitive measurement of four current-use pesticides. These semi-volatile pesticides were calibrated with injections of solutions onto a filter and subsequently volatilized to generate gas-phase analytes. Trifluralin and atrazine are detected as iodide–molecule adducts, while permethrin and metolachlor are detected as adducts between iodide and fragments of the parent analyte molecule. Limits of detection (1 s) are 0.37, 0.67, 0.56, and 1.1 µg m−3 for gas-phase trifluralin, metolachlor, atrazine, and permethrin, respectively. The sensitivities of trifluralin and metolachlor depend on relative humidity, changing as much as 70 and 59, respectively, as relative humidity of the sample air varies from 0 to 80 %. This measurement approach is thus appropriate for laboratory experiments and potentially near-source field measurements.

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Short summary
The impact of atmospheric chemistry on the fate and transport of pesticides is poorly understood. This paper describes a method for real-time measurements of four common-use pesticides in the gas phase using chemical ionization mass spectrometry. The calibration approach for atmospheric semi-volatile pesticides is described in detail.