The Impacts of Wipe Sampling Variables on Method Performance for Hazardous Pesticide Environmental Samples
Citation:
Willison, S., Dan Stout, A. Mysz, J. Starr, D. Tabor, B. Wyrzykowska-Ceradini, J. Nardin, E. Morris, AND E. Snyder. The Impacts of Wipe Sampling Variables on Method Performance for Hazardous Pesticide Environmental Samples. American Society of Mass Spectrometry, San Diego,CA, June 03 - 08, 2018.
Impact/Purpose:
Excessive application or off-label use of pesticides have resulted in inappropriate use for indoor environments. Surface wipe sampling and analysis techniques are relied upon to successfully evaluate contamination and facilitate remediation efforts. No consensus on sample collection for surfaces exists, and Federal, State and local agencies responding to an incident may use different procedures. Unless identical sampling materials and procedures are implemented in the field, the results are difficult to compare and interpret. This investigation focuses on understanding the impacts of specific variables associated with a wipe sampling procedure affect target analyte recoveries. Different wipe sampling variables and techniques were evaluated so that those responding to pesticide misuse incidents can better assess method performance. Methods (Word Limit- 120) Test parameters were selected based on their effect on method performance. They include wipe material, wipe solvent (for wetting the wipe), permeable and non-permeable surfaces, high and low pesticide concentrations, commercial formulations, and the number of wipes used for each sample (to inform composite sampling). Malathion and carbaryl were used to represent organophosphate and carbamate pesticides, respectively. A wipe sampling procedure was tested implemented for all samples in this investigation. Wipe samples were extracted with hexane and analyzed by gas chromatography-mass spectrometry (GC-MS). An ANOVA statistical analysis was used to compare the results for each tested wipe sampling variable. Preliminary Data (Word Limit- 300) Very little is known how different sampling materials and procedures affect method performance. Five different wipe types and two different wetting solvents were evaluated for pesticide recovery and extraction efficiency from the surface. Cotton twill wipes, cotton balls, and pre-packaged, pre-wetted wipes all demonstrated higher recovery results of target pesticides than loosely woven materials, such as cotton gauze and filter paper. This suggests that densely packed materials such as tightly woven textile or pre-wetted wipes facilitate better pesticide recoveries. Wetting solvents also impacted recoveries. However, using multiple wipes on a single surface (composite sampling) can alleviate deficiencies associated with less compatible solvents and wipe materials. Operational aspects that field samplers may encounter during an incident include high pesticide concentrations, commercial formulations and porous/permeable surfaces. Generally, our results show neither high concentrations nor commercial formulations of the target analytes appear to affect wipe recovery results on a non-porous surface. Porous/permeable surfaces continue to be a challenge and produce low recovery results. On non-porous materials, neat malathion recoveries were 73-86 % for twill and pre-wetted, pre-packaged wipes. Recoveries for tested malathion formulations were 78-124 % for pre-wetted, pre-packaged wipes and cotton gauze wipes on non-porous materials. On non-porous surfaces, neat carbaryl and formulations exhibited recoveries of 82-115 % and 77-110 %, respectively, for all tested wipe materials. While not every wipe sampling variable could be tested, the collected information will be useful in identifying surface sampling limitations. The data may be applicable to chemicals with similar physio-chemical properties.
Description:
Poster -- Investigating the impacts of wipe sampling variables on pesticide surface recovery results and method performance