Immunochemical screening of pesticides (simazine and cypermethrin) in orange oil.

Pesticide residue analysis in citrus oils is very important for their quality and marketing. This study assessed the reliability and sensitivity of enzyme-linked immunosorbent assays (ELISA) for simazine and cypermethrin screening in orange oil. Simazine was analyzed after extraction of the oil with methanolic phosphate buffer with a limit of quantitation (LOQ) of 40 mu g/L for 1-fold and similar to 100 mu g/L for 10-fold oils. Due to matrix effects the immunoanalysis of cypermethrin required hexane-acetonitrile partitioning followed by silica solid phase extraction. The method detected levels higher than 0.5 ppm (mg/L). This LOQ is lower than the U.S. EPA tolerance level (0.9 ppm) for cypermethrin in citrus oils. A good correlation (r(2) 0.99) between ELISA and LC-MS/MS was observed for the analysis of both analytes in 1-fold orange oil. Immunochemical screening can be used to reduce instrumental analysis costs by its use in preliminary orange oil screening.