Insecticides extraction from banana leaves using a modified QuEChERS method

An analytical method employing gas chromatography (GC) with nitrogen–phosphorus detection has been developed for the simultaneous determination of eight insecticides (seven organophosphorus pesticides: ethoprophos, diazinon, chlorpyrifos-methyl, fenitrothion, malathion, chlorpyrifos and fenamiphos, and one thiadiazine: buprofezin) in banana leaves that are currently being used to feed cattle or hogs. The extraction and preconcentration of these pesticides were carried out using a modified QuEChERS procedure and the whole method was validated in terms of repeatability, linearity, precision and accuracy. Triphenylphosphate was used as internal standard. Matrix effect evaluation was also carried out using a matrix matched calibration. The developed procedure gave satisfactory recovery (89–104%) and relative standard deviation values (<9.1%) for the studied pesticides in banana leaves, while limits of detection ranged between 0.002 and 0.064 mg/kg. The method was finally applied to the determination of these pesticides in 12 treated banana leaves samples collected at different banana cultivars of the Canary Islands. Residues of chlorpyrifos were found in ten of these samples. Pesticide confirmation was carried out by GC with tandem mass spectrometry detection.