Device for extracting organic compounds from material in particle form that comes from atmospheric samples, using solvents heated by the application of focalized microwaves in open, non-pressurized systems, which comprises: a magnetron; - an electronic control circuit of the magnetron; - a distillation flask with a neck which is suitable for containing the solvent with the sample to be heated; - a reflux means which permits condensing the vapor produced by the distillation; - a microwave blocking filter, which allows the exit of the vapor produced by the ebullition of the solvent with the sample towards the reflux means; and - a waveguide, which has at one end the magnetron and the electronic control circuit, and at the other end the distillation flask to be heated, the microwave blocking filter and the reflux means, characterised in that said blocking filter is constituted by a plurality of conductor plates with cylindrical cavities, the neck of the distillation flask passing through the centres of said cavities, said plates being disposed in parallel position and all ending connected in short circuit in the exterior perimeter, and open in the interior perimeter of the neck zone of the distillation flask; wherein the device is adapted such that in use the distance between the open interior perimeter and the exterior perimeter closed in short circuit, is a quarter wavelength (λ/4) of the emission frequency of the magnetron, such that the cavities ending in short circuit in the exterior perimeter transform into open circuits for the electromagnetic wave in the interior perimeter, where the neck of the distillation flask passes, and as a consequence the passage of electromagnetic waves is blocked. - an electronic control circuit of the magnetron; - a distillation flask with a neck which is suitable for containing the solvent with the sample to be heated; - a reflux means which permits condensing the vapor produced by the distillation; - a microwave blocking filter, which allows the exit of the vapor produced by the ebullition of the solvent with the sample towards the reflux means; and - a waveguide, which has at one end the magnetron and the electronic control circuit, and at the other end the distillation flask to be heated, the microwave blocking filter and the reflux means, characterised in that said blocking filter is constituted by a plurality of conductor plates with cylindrical cavities, the neck of the distillation flask passing through the centres of said cavities, said plates being disposed in parallel position and all ending connected in short circuit in the exterior perimeter, and open in the interior perimeter of the neck zone of the distillation flask; wherein the device is adapted such that in use the distance between the open interior perimeter and the exterior perimeter closed in short circuit, is a quarter wavelength (λ/4) of the emission frequency of the magnetron, such that the cavities ending in short circuit in the exterior perimeter transform into open circuits for the electromagnetic wave in the interior perimeter, where the neck of the distillation flask passes, and as a consequence the passage of electromagnetic waves is blocked.