Analysis of new designer drugs and common drugs of abuse in urine by a combined targeted and untargeted LC-HR-QTOFMS approach

The development of a liquid chromatography high-resolution mass spectrometry quadrupole-time-of-flight (LC-HRMS-QTOF) method for the analysis of new stimulant designer drugs (e.g. phenethylamine, amphetamine, cathinone and piperazine derivatives) and common drugs of abuse (e.g. ketamine and ritalinic acid) in urine is reported. Sample preparation was carried out by a fast and convenient salting-out liquid-liquid extraction (SALLE) procedure. The data was generated by a preferred target list combined with untargeted data-dependent acquisition recording additional sample information (i.e. not listed metabolites of target compounds or not database-stored drugs). The identification is realised by a fully automated data extraction algorithm, taking into account accurate mass spectra, fragment masses and retention times. Method validation comprised selectivity, linearity, accuracy, stability, determination of the limit of detection (LOD) and limit of quantification (LOQ) and evaluation of matrix effects and recoveries for a total set of 39 compounds. Acceptable quantitative results were obtained for 35 of the 39 analytes. Exemplarily, application of the additional untargeted data-dependent acquisition mode enabled the identification of metabolites of the preferred target list compounds ketamine and methylenedioxypyrovalerone (MDPV) without use of reference standards. Therefore, improvement of the database is feasible with every positive library hit. The approach presented here provides a very useful tool for the combined targeted and untargeted analysis of drugs of abuse in biological matrices such as urine.