Prevalence of new psychoactive substances: A retrospective study in hair.

New psychoactive substances are conquering the drug scene. Police seize different colourful packages with exceptional names. They are declared as 'bath salts', 'plant food', or 'research chemical powders'. Little is known about the actual prevalence of these drugs. Reanalysis of hair samples from routine cases concerning the presence of new psychoactive substances or 'smart drugs' should provide insight into changing patterns of designer drugs. All hair samples from 2009 and 2010 that originally tested positive for amphetamines or MDMA (N = 325) were reanalyzed for new or smart drugs such as 4-fluoroamphetamine, piperazines (BZP, mCPP and TFMPP), cathinones (4-MMC (mephedrone), methylone, butylone, ethylone, MDPV, methcathinone and cathinone), methylphenidate and ketamine. Hair snippets were extracted using a two-step extraction procedure. The analytes were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) (electrospray ionization; multiple-reaction-monitoring mode - information dependent acquisition - enhanced product ion scan). New psychoactive substances were found in 120 cases (37%). Concerning the piperazine drugs, mCPP was positive in 34 (10.5%) cases and TFMPP in one case. Five mCPP cases were also positive for trazodone, an antidepressant which is metabolized to mCPP. In 11 (3%) cases, 4-MMC was detected. Concerning the smart drugs, methylphenidate was found in 16 (5%). Ketamine was found in 45 (14%) cases. 4-Fluoroamphetamine was identified in 12 (4%) cases and methylone in one case.In conclusion, there is a high prevalence of these drugs. Consequently, at least the most common ones (e.g. mCPP, KET, 4-MMC and 4-FA) should be included in screening procedures in clinical and forensic toxicology.