Abstract: A portable plasma based diagnostic apparatus comprising a plasma source for producing energy projectiles atmospheric pressure, a mass analyzer, a sampling interface for receiving direct sample to be analyzed, the sampling interface being positioned between the plasma source and the mass analyzer, a database containing a library of biomarkers with their associated mass spectra, a processor operatively connected to the plasma source, the mass analyzer and the database. The processor is so configured so as to obtain from the mass analyzer a sample mass spectrum of parent and fragment ions resulting form the collision between the energetic projectiles and the sample, compare the sample mass spectrum with mass spectra in the reference library in order to identify at least one indicator and provide a report based on the at least one identified indicator.