Submitted to: Journal of the Association of Official Analytical Chemists
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 18, 2000
Publication Date: N/A
Interpretive Summary: When samples for pesticide content are collected in one location to be shipped some distance for analysis, the integrity of the samples during shipment, and the cost of shipping volumes of water, become important issues. If the pesticides in the samples can be extracted from the water onto some lightweight adsorbent material which holds the pesticides without degradation, both of the above concerns are rectified. The paper reports on a study of the utility of a polymeric adsorbent disk for extraction and stabilization for shipment four commonly applied pesticides. The study has shown that greater than 70-80% recoveries from the disks were attainable after shipment of the disks with adsorbed pesticides to a distant laboratory for analysis.
Inter-laboratory comparison was conducted to examine the utility of using C-18 solid-phase extraction disks (Empore) to simultaneously determine the herbicides atrazine, bromacil, and metolachlor and the insecticide chlorpyrifos in water samples. The protocol consisted of paired locations coordinating their activities and shipping fortified water samples or Empore disks onto which the pesticides had been retained and then quantifying the analytes using a variety of gas chromatographic methods. Average recoveries from all laboratories were greater than 80% for atrazine, bromacil, and metolachlor, and greater than 70% for chlorpyrifos. Shipping samples between cooperating laboratories did not affect recovery of atrazine, chlorpyrifos, or metolachlor in both matrices. Recoveries tended to be higher where disks were shipped to cooperating labs compared with fortified water. Shipping disks eliminated many problems associated with the shipment of water samples, such as bottle breakage, higher shipping cost, and possible pesticide degradation. Recoveries were lower from fortified surface water samples compared to fortified deionized water samples for bromacil and metolachlor. This collaborative research demonstrated that water samples could be concentrated onto an Empore solid-phase extraction disk at one location and quantified using diverse analytical conditions at another location.