STABILITY OF POLAR PESTICIDES ON DISPOSABLE SOLID-PHASE EXTRACTION PRECOLUMNS

The stability of representatives of different groups of polar pesticid es (triazines, phenylureas, carbamates, chlorinated phenols) sorbed fr om water samples onto a polymer sorbent and stored under different con ditions 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 com pounds that had acidobasic properties. The results obtained with surfa ce water were similar to those obtained with tap water. In general, so lid-phase extraction was confirmed to be a suitable technique when lon g-term preservation of analytes prior to analysis is required. (C) 199 8 Elsevier Science B.V.