Method for the analysis of 4-nitrophenol and parathion in soil using supercritical fluid extraction and immunoassay

Jennifer M. Wong, Qing Xiao Li, Bruce D. Hammock, James N. Selber

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


Analysis of trace residues of pesticides and their breakdown products in the environment is a continuing need. Recent advances in analytical systems have allowed detection of even lower levels of pesticides. Two recent techniques, supercritical fluid extraction (SFE) and enzyme-linked immunosorbent assay (ELISA), have been integrated for the analysis of 4-nitrophenol and parathion in soil. Carbon dioxide SFE gave recoveries equivalent to liquid extraction with ethy! acetate for soils spiked at 10,1, and 0.1 ppm of each compound. Quantitation of the recovered compounds by ELISA agreed well with analysis by gas chromatography. Parathion extracted from soil was analyzed as 4-nitrophenol by ELISA after oxidation using dimethyldioxirane to paraoxon followed by hydrolysis. Dimethyldioxirane is an easily prepared, volatile, oxidizing reagent that should generally be applicable in converting thionophosphates to their corresponding oxons for analysis. Extraction and analysis by SFE ELISA resulted in greater sample throughput, allowing for rapid screening of a large number of environmental samples. The extraction and derivatization techniques presented here demonstrate a general principle in immunoassay of using volatile extraction solvents and derivatizing reagents to minimize interference with the subsequent immunoassay.

Original languageEnglish (US)
Pages (from-to)1802-1807
Number of pages6
JournalJournal of Agricultural and Food Chemistry®
Issue number10
StatePublished - 1991

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Food Science
  • Chemistry (miscellaneous)


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