The invention relates to an apparatus and a method for analysing a chemical composition of aerosol particles. The apparatus comprises an extractive electrospray ionisation source for extracting components, in particular organic compounds, from the aerosol particles and for ionising the components to ions, and a mass analyser, in particular a time of flight mass analyser, for analysing the ions, the mass analyser fluidly coupled to the extractive electrospray ionisation source. The method includes the steps of extracting components, in particular organic compounds, from the aerosol particles with an extractive electrospray ionisation source and ionising the components with the extractive electrospray ionisation source to ions, transferring the ions to a mass analyser, in particular a time of flight mass analyser, the mass analyser being fluidly coupled to the extractive electrospray ionisation source, and analysing the ions with the mass analyser.