Electrochemical quantification of chlorpyrifos in white (Allium cepa L.) and green (Allium fistulosum L.) onions Cuantificación voltamétrica de clorpirifos en cebolla de bulbo (Allium cepa L.) y cebolla de rama (Allium fistulosum L.)

Abstract

The Linear sweep voltammetry method (LSP) of a common pesticide such as chlorpyrifos (CP) an organophosphate pesticide (OPP) in white (Allium cepa L.) and green onions (Allium fistulosum L.) was investigated. A hanging mercury drop electrode (HMDE) Ag/AgCl was used as reference electrode and platinum as a counter electrode. The OPP was extracted from the onion through liquid-liquid partition using acetone/dichloromethane as the solvent. Validated method was compared with GC/ECD as a reference method. CP concentration was not different between the two analytical techniques; the analysis was performed with a confidence level of 90%, corresponding to the polarographic method. CP concentration was 0.8400 ± 0.062 ppm in Allium cepa and 0.062 ± 0.300 ppm in Allium fistulosum L. These values exceed the ADI and ARD values for chlorpyrifos established by current regulations.