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ARS Home » Research » Publications at this Location » Publication #89390
Title: DERIVATIZATION REACTIONS OF CARBAMATE PESTICIDES IN SUPERCRITICAL CARBON DIOXIDE (SC-CO2)

Author
item ZHANG, ZHOUYAO - FORMER USDA, ARS EMPLOYEE
item King, Jerry

Submitted to: Pittsburgh Conference
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Because of the wide spread use of toxic N-methylcarbamates as insecticides for agricultural products and concerns of their contamination in food and drinking water supplies, various methods have been developed for monitoring the concentration levels of these carbamates. Typically, carbamates are extracted with organic solvents or by supercritical fluid extraction (SFE) and analyzed by either precolumn derivatization for gas chromatography (GC), or postcolumn derivatization using high performance liquid chromatography (HPLC). A method was developed to derivatize carbamates in supercritical carbon dioxide (SC with CO2), thus the extraction and derivatization are accomplished in one step, and the SFE extract is ready for GC analysis without the need for further treatment. Five derivatization reactions were studied, and derivatization with heptafluorobutyric anhydride (HFBA) was the most successful. The derivatized carbamates were confirmed using GC with ion trap mass spectrometry (MS). The conversion of carbamates was complete as indicated by HPLC dual post column hydrolysis and ortho phthalaldehyde derivatization followed by fluorescence detection. The fluorinated derivatives can also be analyzed by GC with electron capture detector (ECD) or GC with MS with excellent sensitivity. Because supercritical fluids have unique properties such as adjustable mass transport, the above derivatization reaction in SC with CO2 is much more efficient than in an organic solvent. Compared with the same HFBA reaction in an organic solvent, the derivatization reaction time was considerably shortened as well as eliminating organic solvent in the derivatization step.