|Bresnahan, Gail - NORTH DAKOTA STATE UNIV|
|Dexter, Alan - NORTH DAKOTA STATE UNIV|
|Barber, Brian - UNIVERSITY OF MINNESOTA|
Submitted to: Pittsburgh Conference
Publication Type: Proceedings
Publication Acceptance Date: March 4, 2001
Publication Date: N/A
Technical Abstract: Increased glyphosate use for weed control in glyphosate-tolerant crops has resulted in greater potential off-site deposition causing injury to non-target plants. Glyphosate is difficult to detect at the trace levels that can cause injury to plants using traditional methods of analysis. Another approach has been to determine shikimic acid build up in the plant as a result of glyphosate exposure. HPLC-UV has been used to analyze shikimate in plants, however this method has limitations. The sensitivity of UV detectors allows only for analysis of freshly sprayed plants. Shikimate concentration in plants decreases with time after exposure, and it cannot be detected in dead, brown plant material. We found that shikimate in plants rapidly decomposes and it could not be detected in dead, brown material approximately 6 weeks after glyphosate application. To overcome this limitation, we have developed a method to analyze shikimate using a LC-MS with electrospray (ES) interface. LC-ES-MS enables analysis at levels of sensitivity that are sufficiently low to determine shikimate in dead brown material for longer periods after application.