Mephedrone (4-methylmethcathinone) is a synthetic cathinone derivative which has a similar chemical structure and effects to other stimulant recreational drugs such as amphetamine. Mephedrone was first introduced to the United Kingdom recreational drug market in the years 2007-2008 and has established itself as a widely used new psychoactive substance, responsible for significant morbidity and mortality In a study published in Drug Testing and Analysis, J. Czerwinska et al., (doi: 10.1002/dta.2525), developed a liquid chromatography tandem mass spectrometry method using UCT’s Selectra® PFPP LC column for the simultaneous quantification of mephedrone and five of its phase I in human whole blood after extraction with UCT’s Xtrackt® solid phase extraction (SPE) columns. Mephedrone’s stability in whole blood has been previously investigated but this is the first-time stability of its metabolites has been assessed, indicating -20°C to be the recommended storage condition for all analytes.
In the method, chromatographic separation was performed using a 2.1 mm x 150 mm, 1.8 µm, PFPP Selectra® column held at 60°C. The flow rate was 0.5 mL per minute with 0.3% formic acid in water as mobile phase A and 0.3% formic acid in acetonitrile as mobile phase B. The start of the gradient was at 85% mobile phase A. Mobile phase B was then increased to 55% over 11 minutes and was held for 2 minutes. Over the next 0.5 minutes the gradient returned to the starting condition and the column was re-equilibrated at 85% mobile phase A for the remaining 1.5 minutes. The total run time was 15 minutes.
For SPE extraction, to 100 µL of whole blood, 10 µL of Internal Standard was added. All samples were vortexed and 1 mL of 0.1 M phosphate buffer (pH 6.0) was added. The SPE cartridges were conditioned with 2 mL of MeOH and 2 mL of 0.1 M phosphate buffer (pH 6.0). Samples were loaded and washed with 2 mL of 0.1 M acetic acid followed by 2 mL of MeOH. Samples were eluted with 4 x 1 mL of methylene chloride:propan-2-ol:ammonium hydroxide (78:20:2 v/v/v) and dried under nitrogen at 50°C. Samples were reconstituted with 100 µL of 0.1% formic acid in ACN:water (10:90 v/v).
This study demonstrates both the power and efficiency of both UCT’s Selectra® LC column for the separation of NPS parent and metabolite compounds, and Xtrackt® SPE for the extraction of those compounds from whole blood samples. For more information regarding our consumables please turn to www.unitedchem.com.