Stability of polar pesticides on disposable solid-phase extraction precolumns

The stability of representatives of different groups of polar pesticides (triazines, phenylureas, carbamates, chlorinated phenols) sorbed from water samples onto a polymer sorbent and stored under different conditions was investigated. The results confirmed the stability of most of the pesticides stored on the sorbent during a seven-week period at room temperature or in the refrigerator after sorption from tap water. The differences between the stability of analytes when stored on wet or silica gel-dried sorbent were negligible. The pH value of the water sample had a significant influence on the stability of only those compounds that had acidobasic properties. The results obtained with surface water were similar to those obtained with tap water. In general, solid-phase extraction was confirmed to be a suitable technique when long-term preservation of analytes prior to analysis is required. (C) 1998 Elsevier Science B.V.