Mass spectrometry is an optoelectronic method of determining organic substances by comparing their mass spectrum with mass spectra found in system libraries. In the case of biological products, substances of interest, biotic or xenobiotics, may be “hidden” from the background of the analyzed matrix noise, which alters the major aspect of the mass spectrum obtained and faces the impossibility of their identification. A gas chromatograph coupled with mass spectrometer (GC-MS) Varian, was used to develop the application. Authors presented two methods for increase the sensitivity or the signal/noise ratio for identification the cocaine and their metabolite ethylbenzoylecgonine (EBE).