You are here:
Analysis of Organophosphorus-Based Pesticides from Surfaces Using Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
Citation:
Willison, S. Analysis of Organophosphorus-Based Pesticides from Surfaces Using Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS). U.S. EPA Office of Research and Development, Washington, DC, 2016.
Impact/Purpose:
The sampling and analytical method described herein was developed and tested within the same laboratory to assess the recoveries of organophosphorus-based pesticides from wipe samples from various porous (vinyl tile, painted drywall) and mostly nonporous (laminate, galvanized steel, glass) surfaces. Performance data (method detection limits and precision and accuracy data) are available to demonstrate the fitness-for-purpose regarding the development of a method for organophosphorus-based pesticides in a single laboratory. Samples are collected from surfaces using wipes, which are then spiked with a surrogate compound and carried through extraction with acetonitrile, sonication, and filtration steps followed by analysis using liquid chromatography electrospray ionization/tandem mass spectrometry (LC/ESI-MS/MS) by direct injection without derivatization. Detection limit data were generated using wipes on a metal surface following the procedures of 40 CFR Part 136, Appendix B, as part of EPA’s guidelines for determining a method detection limit. Gauze wipes were selected because they were found to be physically robust during the wiping procedure, contained low background levels, produced no peaks that interfered with the target analytes, and produced the highest percent recoveries during sample analysis. Percent recoveries were highest for the non-porous/non-permeable surface types (laminate, metal, and glass). Recoveries from these types of surfaces ranged from 60-107 % at the lowest tested concentration levels for 8 of 13 of the organophosphorus-based pesticides (OPs) analyzed in ESI positive mode. The method resulted in lower recoveries for two of the tested analytes (19-53 %), most likely due to degradation, interference, or volatilization. The remaining three tested analytes performed poorly and should not be considered for this method without further evaluation; however, the data are listed for all tested analytes. The resulting equivalent method detection limits obtained from wiping the metal surface were 0.08 ng/cm2 for dichlorvos, 0.025 ng/cm2 disulfoton-sulfone, 0.022 ng/cm2 chlorpyrifos-oxon, 0.10 ng/cm2 chlorpyrifos, 0.01 ng/cm2 fenamiphos, 0.013 ng/cm2 chlorfenvinphos, 0.01 ng/cm2 monocrotophos, 0.016 ng/cm2 methamidophos, 0.025 ng/cm2 mevinphos, 0.013 ng/cm2 disulfoton-sulfoxide, 0.047 ng/cm2 fenamiphos-sulfone, and 0.038 ng/cm2 fenamiphos-sulfoxide.
Description:
Sampling and Analysis Procedure/Method The method was tested for 13 different OP-based pesticides; however, further investigation is needed for dichlorvos, disulfoton, and mevinphos. The wiping and analytical procedure for these analytes resulted in highly variable data and/or non-detected values. Chlorpyrifos and methamidophos resulted in low or variable recoveries and may need additional investigation. Complications are presented in Section 14.4 of the method. Precision and accuracy data were generated from each tested surface fortified with all analytes.