Simultaneous determination of 20 drugs of abuse in oral fluid using ultrasound-assisted dispersive liquid–liquid microextraction
Drugs of abuse and new psychoactive substances (NPS) for recreational purposes are in constant evolution, and their consumption constitutes a significant risk to public health and road safety. The development of an analytical methodology to confirm the intake of illicit drugs in biological fluids is required for an effective control of these substances. An ultra-performance liquid chromatography–tandem mass spectrometry method (UPLC-MS/MS) was developed for simultaneous determination of 10 synthetic cathinones and 10 illicit drugs in oral fluid easily sampled through non-invasive maneuvers. The UPLC-MS/MS method was coupled to an ultrasound-assisted dispersive liquid–liquid microextraction (US-DLLME), which is a miniaturized and inexpensive technique that uses reduced volumes of solvents and samples. The US-DLLME was optimized by using a 213441//18 asymmetric screening design and a Doehlert design. Sample volume, dispersion and extraction solvent volumes, pH, US time, and amount of sodium chloride were evaluated. The US-DLLME-UPLC-MS/MS method was validated according to international guidelines. Limits of quantitation (LOQs) ranged from 0.25 to 5 ng mL−1, and the linear range spanned from LOQ to 500 ng mL−1 with R2 higher than 0.9907, for most of the target drugs. Precision ranged from 1.7 to 14.8 %RSD. Accuracy, i.e., extraction recovery, ranged from 74 to 129%. The proposed method was successfully applied to the analysis of 15 samples from patients on a drug detoxification program.
KeywordsDrugs of abuse Oral fluid Scopolamine Synthetic cathinones UPLC-MS/MS Ultrasound-assisted dispersive liquid–liquid microextraction
The authors are grateful to Professor M.I. Loza (BioFarma Research Group–USC) for assistance with the instrumentation.
This work was funded by Ministerio del Interior-DGT (Project SPIP2015-01838) of Spain and the European Regional Development Fund (FEDER).
Compliance with ethical standards
This study has been carried out using oral fluid samples from healthy volunteers and patients participating in substitution therapy programs, authorized by the Comité Autonómico de Ética da Investigación de Galicia Consellería de Sanidade. Xunta de Galicia (SPAIN), with the reference 2015/488, according to Spanish Regulation Law 14/2007, of biomedical investigation and the Real Decreto 1716/2011, of November 18. All the samples have been provided by volunteers and patients who did not oppose to the use of these samples for the development of an analytical method and signed the corresponding informed consent.
Conflict of interest
All authors declare that they have no conflict of interest.
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