A method for the detection of at least one nano or micro plastic particle comprised in a heterogeneous matrix material comprising the following steps: a) applying of at least one part of a heterogeneous matrix material comprising the at least one nano or micro plastic particle onto at least a portion of a surface of a focused ion beam irradiable conductive support thereby forming a first layer onto said surface, said first layer having an average thickness equal to or lower than 10 μm, the heterogeneous matrix being a medium in which the at least one nano or micro plastic particle is embedded together with a substance or a mixture of substances, the medium being selected from the group consisting of a liquid, a solution, a suspension, a paste, a cream, a tissue and wherein the heterogeneous matrix is a naturally occurring substance selected from the group consisting of cell cultures grown on a surface, creams obtained from seafood, cultures obtained by spreading-plating methods; b) irradiating of at least a portion of said first layer with at least one ion beam to at least partially or completely digest the heterogeneous matrix, except for the nano and micro plastic particles comprised in the heterogeneous matrix, thereby forming an irradiated layer, the at least a portion of said first layer being irradiated by using a Ga + focused ion beam with a radiation dose which varies from 1*10 13 to below 1*10 11 ions/cm 2 or with a radiation dose which varies from above 1*10 17 to 1*10 20 ions/cm 2, c) detecting of the at least one nano or micro plastic particle comprised in said irradiated layer as formed in step b) by a detection method chosen from the group of a mass spectroscopic technique, or a Raman nanoscopic technique, or an infrared nanoscopic technique, or a charge dependent detection method, or a combination thereof, wherein the charge dependent detection method is chosen from the group of SEM, EDX and combinations thereof. a) applying of at least one part of a heterogeneous matrix material comprising the at least one nano or micro plastic particle onto at least a portion of a surface of a focused ion beam irradiable conductive support thereby forming a first layer onto said surface, said first layer having an average thickness equal to or lower than 10 μm, the heterogeneous matrix being a medium in which the at least one nano or micro plastic particle is embedded together with a substance or a mixture of substances, the medium being selected from the group consisting of a liquid, a solution, a suspension, a paste, a cream, a tissue and wherein the heterogeneous matrix is a naturally occurring substance selected from the group consisting of cell cultures grown on a surface, creams obtained from seafood, cultures obtained by spreading-plating methods; b) irradiating of at least a portion of said first layer with at least one ion beam to at least partially or completely digest the heterogeneous matrix, except for the nano and micro plastic particles comprised in the heterogeneous matrix, thereby forming an irradiated layer, the at least a portion of said first layer being irradiated by using a Ga + focused ion beam with a radiation dose which varies from 1*10 13 to below 1*10 11 ions/cm 2 or with a radiation dose which varies from above 1*10 17 to 1*10 20 ions/cm 2, c) detecting of the at least one nano or micro plastic particle comprised in said irradiated layer as formed in step b) by a detection method chosen from the group of a mass spectroscopic technique, or a Raman nanoscopic technique, or an infrared nanoscopic technique, or a charge dependent detection method, or a combination thereof, wherein the charge dependent detection method is chosen from the group of SEM, EDX and combinations thereof.