Simultaneous screening and quantitation of stimulant drugs in dried blood spot (DBS) samples using ultra-high performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS)

Abstract

Dried blood spots (DBS) have seen recent development as an alternative to whole blood samples for drug testing. The ease of use of DBS makes the technique suitable and attractive for drug testing applications. Quantitation of drug concentrations in the ng/mL range can be achieved from DBS samples using 10 to 20 µL of blood. The establishment of drug per se limits for drivers requires timely methods of sampling blood for accurate drug concentration measurements. Method validation for the analysis of forensically relevant stimulant drugs and their metabolites in DBS samples by ultra-performance liquid chromatography-quadrupole time-of-flight high-resolution mass spectrometry (UPLC-QTOF-MS) is presented. DBS blood samples were prepared by spiking 20 µL of blood-containing analytes ranging from 10 to 1000 ng/mL onto Whatman® 903 Protein Saver cards. Analytes were extracted from whole DBS samples punched from protein saver cards by sonication in water followed by PRiME® MCX μElution solid phase extraction. An LOQ of 10 ng/mL was achieved for all analytes. Precision (0.09% to 14.67%), bias (–17.15% to 13.91%) and matrix effects (–18.7% to 23.4%) were suitable for validation in 10/14 analytes. DBS drug stability varied by analyte. DBS sampling may assist in overcoming forensic challenges associated with blood sampling, and accurate drug quantitation even at low concentrations is possible. The results of this work suggest that DBS microsampling is suitable for drug-impaired driving cases in jurisdictions where per se limits for drugs exist, particularly for zero-tolerance drug limits.