Aptamer-modified carbon nanomaterial based sorption coupled to paper spray ion mobility spectrometry for highly sensitive and selective determination of methamphetamine

A cellulose paper was modified with an aptamer against methamphetamine on either carbon dots (CDs) or on multichannel carbon nanotubes (CNTs). The resulting sorbent was applied to the extraction of METH from blood or saliva. The METH-loaded paper than also was directly applied as a paper spray ionization source in ion mobility spectrometry. The carbon nanomaterial enhances sensitivity, and the aptamer enhances selectivity. The materials were covalently bound to the paper on one side, while the aptamer was immobilized on the other. After optimization of the extraction process and instrumental parameters, the limits of detection when using the aptamer-CNT modified paper are 0.6 ng.mL(-1) for saliva, and 0.45 ng.mL(-1) for plasma. The respective values when using aptamer-CD modified paper are 1.5 ng.mL(-1) for saliva and 0.9 ng.mL(-1) for plasma. Calibration plots are linear in the 2 to 150 ng.mL(-1) METH concentration range for saliva, and in the 1.5 to 200 ng.mL(-1) concentration ranges for blood when using the aptamer-CNT based method. When using the aptamer-CDs, the dynamic ranges extend from 5 to 200 ng.mL(-1) and from 3 to 250 ng.mL(-1), respectively. The method was applied to the determination of METH in real samples of saliva and blood, and the accuracy of the method was confirmed by comparison of the results with data analyzed by GC-MS.