Paper-based monolith extraction of psychoactive substances from biological fluids.

A monolith of poly(methacrylic acid-co-ethylene glycol dimethacrylate) has been immobilised to a nitrocellulose strip by radical photopolymerisation to be used in the extraction of psychoactive substances in biological fluids. Codeine, methylone, amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine, butylone, norketamine, ketamine, heroin, cocaine, lysergic acid diethylamide and fentanyl were employed as model drugs and final extracts were analysed by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Polymerisation parameters were adjusted in order to obtain a stable and homogeneous layer of monolith onto the nitrocellulose strip. The resulting sorptive phase was characterized by Fourier-transform infrared spectroscopy and scanning electron microscopy. Extraction conditions were investigated by the evaluation of sample pH, extraction and desorption times and desorption solvent volume, providing enrichment factor values ranging from 5.3 to 39.9. The proposed methodology provided limit of quantification values from 0.013 μg L-1 for methylone to 0.057 μg L-1 for amphetamine, and recoveries from 64 to 120%. Urine and serum certified reference materials were employed in the validation of the proposed methodology, providing results statistically comparable. The developed approach is simple and straightforward for the determination of psychoactive substances in urine and serum samples.