Liquid chromatography–tandem mass spectrometric methods for the determination of spinosad, thiacloprid and pyridalyl in spring onions and estimation of their pre-harvest interval values

•LC–MS/MS methods for the determination of spinosad, thiacloprid & pyridalyl in spring onions are presented.•A multi-residue method and a specific one for pyridalyl were developed and validated.•Thorough optimisation of analytical parameters (mobile phase, ionisation) was performed.•Degradation rates, PHIs and half-life values of the pesticides were calculated.•A pre-harvest interval of 10days was achieved for thiacloprid, 39.4days for pyridalyl and 0days for spinosad.