Electron ionization (EI) was carried out under following conditions: 70 eV ionization energy, 50 mA emission current and 200 C source temperature. Pressure of collision gas (argon) and acquisition cycle time were set to 1 mTorr and 0.2 s, respectively. GCeMS screening of major matrix components was performed using the full scan mode acquiring m/z from 50 to 650.