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.