Interlaboratory comparison of extraction efficiency of pesticides from surface and laboratory water using solid-phase extraction disks.

A continuation of an earlier interlaboratory comparison was conducted (1) to assess solid-phase extraction (SPE) using Empore disks to extract atrazine, bromacil, metolachlor, and chlorpyrifos from various water sources accompanied by different sample shipping and quantitative techniques and (2) to compare quantitative results of individual laboratories with results of one common laboratory. Three replicates of a composite surface water (SW) sample were fortified with the analytes along with three replicates of deionized water (DW). A nonfortified DW sample and a nonfortified SW sample were also extracted.

Interlaboratory comparison of pesticide recovery from water using solid-phase extraction disks and gas chromatography.

An interlaboratory study was conducted to assess the suitability of C18 solid-phase extraction disks to retain and ship different pesticides from water samples. Surface and deionized water samples were fortified with various pesticides and extracted using C18 disks. Pesticides were eluted from disks and analyzed in-house, or disks were sent to another laboratory where they were eluted and analyzed.