Development of an LC-MS/MS method for determining 5-MeO-DIPT in dried urine spots and application to forensic cases

The dried urine spots (DUSs) technique is increasing continuously as an easy sampling method for monitoring substance abuse due to its advantages of stability and convenience regarding transport and storage. 5-Methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT) is a new type of tryptamine hallucinogen, the use of which has been banned in many countries. And according to the previous research, 5-MeO-DIPT is not stable in urine. In order to improve its stability, an LC-MS/MS method for determining 5-MeO-DIPT in DUSs was developed.

10 μl urine was spotted on Whatman FTA^TM classic card, then extracted with 200 μl methanol, and liquid chromatography-tandem mass spectrometry in positive ion multiple reaction monitoring mode was utilized for analysis.

The LOD and LLOQ of the method were 0.1 ng/ml and 0.2 ng/ml, respectively. The accuracy and precision were 98.2%-103.9% and 2.7%-8.5%, respectively. It was found that the stability of 5-MeO-DIPT in DUSs was better than the stability of 5-MeO-DIPT in urine stored at 25 °C. Moreover, this method was also applied to detect 5-MeO-DIPT in the urine of individuals known to have used 5-MeO-DIPT. It was found that the concentrations of 5-MeO-DIPT were 0.3-2.3 ng/ml, which were lower than those obtained via GC-Orbitrap-MS. The small volume of urine required (10 μl), combined with the simplicity of the analytical technique, makes this an useful procedure for the screening of drug of abuse.