The ability of forensic laboratories to detect and identify unknown compounds is highly important since new, non-controlled designer drugs are appearing on the market with increasing frequency. In this study, the combined use of gas chromatography-mass spectrometry (GC-MS) and ultra performance liquid chromatography-quadrupole time of flight-mass spectrometry (UPLC-QTOF-MS) was used for screening of new unknowns. In one large seizure from a Danish Internet company, ten different drugs were identified. Several of the compounds were seized for the first time in Denmark. The GC-MS and UPLC-QTOF-MS analyses were supplemented by nuclear magnetic resonance (NMR) spectra for the structural elucidation of p-fluoroamphetamine, mephedrone (4-methylmethcathinone), flephedrone (4-fluoromethcathinone), PPP (a-pyrrolidinopropiophenone), MDPV (3,4-methylenedioxypyrovalerone), Bk-MBDB (2-methylamino-1-(3,4-methylenedioxyphenyl)butan-1-one), pFBT (3-(pfluorobenzoyl)-tropane), and JWH-073 (1-butyl-3-(1-naphthoyl)indol), whereas methylone (3,4-methylenedioxymethcathinone) and N-ethylcathinone matched electron impact-mass spectrometry (EI-MS) library spectra and therefore the screenings were considered sufficient. EI-MS spectra and the proposed main fragmentation patterns are presented as well as QTOF-MS exact masses and fragments and NMR chemical shifts. For the ß-ketophenylethylamines (mephedrone, flephedrone, PPP, MDPV, Bk-MBDB, methylone, and N-ethylcathinone) some general fragmentation patterns observed in the EI-MS and QTOF-MS spectra are further discussed and compared to other ß-ketophenylethylamines.