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

(DAV-1117-036518) Determination of Potential Transformation Products and Reaction Pathways of Selected Organophosphate Pesticides in Several Waters.

Davis, E¹, Haley, M¹, Anthony, J¹, ¹ US Army Edgewood Chemical Biological Center (ECBC), MD

ABSTRACT- Degradation experiments were performed on three organophosphate pesticides, mevinphos, dicrotophos, and dichlorvos in natural and distilled waters using an Agilent 1100 Series high performance liquid chromatography (HPLC) with reversed phase separation (RP) coupled with UV detection. A further method was developed to investigate the identification of the degradation products in these waters by mass spectroscopy (LC-MS) using atmospheric chemical ionization (APCI) in the positive ion mode. The MS detection was accomplished using total ion current (TIC) mode in order to elucidate potential structures that could provide evidence for suggested hydrolysis pathways. No sample pretreatment was required for the analysis. Under the conditions determined for the separation of the pesticides, the MS detection gave peaks with an m/z equal to +1, except for dichlorvos, indicating ionization of the pesticides from a charge transfer of a proton. No products were found using negative ion mode, APCI.

Key words: organophosphate pesticides, hydrolysis, LC-MS-APCI