Development of a rapid LC-MS/MS method for direct urinalysis of designer drugs

The current immunoassay screening methodologies used to detect sympathomimetic amines within the context of workplace drug testing may fail to detect a number of the emerging designer drugs, for example β-keto amphetamines and piperazine derivatives, commonly referred to as 'legal highs'. Therefore, a rapid multi-analyte qualitative screening method, using ultra-high-pressure liquid chromatography-tandem mass spectrometry (LC-MS/MS), was investigated for analysis of new designer drugs that have emerged from the former legal highs market. Eight analytes were targeted as model compounds: 4-methylmethcathinone (mephedrone), 3,4-methylenedioxymethcathinone (bk-MDMA, 'methylone'), 2-methylamino-1-(3,4-methylenedioxyphenyl)butan-1-one (bk-MBDB, 'butylone'), 4-methoxymethcathinone (bk-PMMA, 'methedrone'), 1-benzylpiperazine (BZP), 1-(3-trifluoromethyl phenyl)-piperazine (TFMPP), 1-(3-chloro phenyl)-piperazine (mCPP), and 3, 4-methylenedioxypyrovalerone (MDPV). The LC-MS/MS method developed encompassed direct analysis following a 1:4 dilution of urine with mobile phase to reduce matrix effects. Although not all compounds were completely resolved chromatographically, two product ions conferred sufficient specificity to allow target analyte identification. Although all target analytes were readily detected at 500 ng/ml, a cut-off of 1000 ng/ml was chosen to mirror the amphetamine screening cut-off commonly used for routine analysis of workplace drug testing samples. In conclusion, direct analysis using LC-MS/MS offers an attractive way forward for the development of a rapid routine screen for new psychoactive substances, particularly given the growing number of novel compounds.