Scheduled multiple reaction monitoring algorithm as a way to analyse new designer drugs combined with synthetic cannabinoids in human serum with liquid chromatography–tandem mass spectrometry

•The LC–MS/MS method was validated in human serum for 33 drugs.•A combined analysis of synthetic cannabinoids and new designer drugs was developed.•The scheduled multiple reaction monitoring algorithm was used.

Here, we describe the development and application of a liquid chromatography–tandem mass spectrometry method with positive electrospray ionisation and scheduled multiple reaction monitoring algorithm (s-MRM) to analyse synthetic cannabinoids (SC) combined with new designer drugs (NDD) in human serum. A Luna 5 μm C18 (2) 100 A, 150 mm × 2 mm analytical column and a mobile phase consisted of A (H2O/methanol = 95/5, v/v) and B (H2O/methanol = 3/97, v/v) – both with 10 mM ammonium acetate and 0.1% acetic acid (pH = 3.2), were used for the separation. A binary flow pumping mode with a total flow rate of 0.400 mL/min was used. A single sample extraction with 1-chlorobutane for both substance groups was performed. Acceptable linearity in the validated calibration ranges of 0.05–1 ng/mL for SC and 1–50 ng/mL for NDD was achieved. The limit of detection was not greater than 0.02/0.40 ng/mL and the limit of quantification not greater than 0.05/0.50 ng/mL for SC/NDD respectively. The presented study revealed that this method is a very effective way for sensitive SC and NDD identification in human serum and has useful application in hospitals, therapy centres and forensic psychiatric centres. S-MRM ensures a method upgrade with a smaller loss of sensitivity, precision and accuracy in comparison to traditional MRM methods. Also addition of new SC and NDD can be performed in the future.