MP5 Agrochemicals and Pesticides
Monday, 14 November 2005: 8:00 AM - 5:30 PM in Exhibit Hall

(FOR-1117-839973) A method for pesticides and degradates in soil and sediment using pressurized fluid extraction and GC/MS.

Foreman, W.¹, Jha, V.¹, Skaates, S.¹, Madsen, J.¹, Sandstrom, M.¹, Stroppel, M.¹, Capel, P.², ¹ U.S. Geological Survey, Denver, CO, U.S.A.² U.S. Geological Survey, Minneapolis, MN, U.S.A.

ABSTRACT- A method for the determination of multiple classes of pesticides and degradates in soil, bed and suspended sediment has been developed that uses pressurized fluid extraction (PFE), extract cleanup with graphitized carbon column and gel permeation chromatography, and analysis by gas chromatography/mass spectrometry (GC/MS) operated in selected ion-monitoring mode. The method was validated for 42 parent pesticides and 24 degradates, with acceptable (60-120% mean) performance obtained for the majority of analytes in most tested matrices. Estimated method detection limits ranged from 0.4-2 ug/kg for a 50-g dry-weight sample. Estimated reporting levels, accounting for recovery, ranged from 1-30 ug/kg (or 5-150 ng/L for a 10-L suspended-sediment sample collected on filter media). Advantages and limitations of the method will be presented, including operational parameters for PFE, clean-up steps, GC/MS, and analyte stability and standard issues. The method was developed to support studies by the U.S. Geological Survey National Water-Quality Assessment Program's Agricultural Chemicals Team (NAWQA–ACT) to investigate the sources, transport, and fate of selected agricultural chemicals in a variety of agricultural settings across the Nation. Field results from NAWQA–ACT pilot studies using this method will be presented.

Key words: pesticides, degradates, sediment, soil