Identification and assay of organophosphates in organic oranges by gas chromatography with pulsed flame photometric detection and ion-trap mass spectrometry

Multiresidue analysis for organophosphates in organic oranges grown in Calabria (Italy) is performed by the combined use of a pulsed flame photometric detector and an ion-trap mass spectrometer simultaneously coupled to a gas chromatograph through a double-hole ferrule. The method provides the retention times (RTs) of the phosphorus-containing analytes only. The extracted ion chromatograms at the previously determined RTs are used for full identification of the species through a mass spectra library search and for quantitative evaluation of each species in the natural matrix. The banned pesticide ronnel was used as an internal standard because of its chemical structure, which is perfectly suited to the performance of both detectors.