Quantitation of Fentanyl Analogs in Dried Blood Spots by Flow-Through Desorption Coupled to Online Solid Phase Extraction Tandem Mass Spectrometry.

An automated dried blood spot (DBS) elution coupled with solid phase extraction and tandem mass spectrometric analysis for multiple fentanyl analogs was developed and assessed. This method confirms human exposures to fentanyl, sufentanil, carfentanil, alfentanil, lofentanil, α-methyl fentanyl, and 3-methyl fentanyl in blood with minimal sample volume and reduced shipping and storage costs. Seven fentanyl analogs were detected and quantitated from DBS made from venous blood. The calibration curve in matrix was linear in the concentration range of 1.0 ng/mL to 100 ng/mL with a correlation coefficient greater than 0.98 for all compounds. The limit of detection varied from 0.15 ng/mL to 0.66 ng/mL depending on target analyte. Analysis of the entire DBS minimized the effects of hematocrit on quantitation. All quality control materials evaluated resulted in <15% error; analytes with isotopically labeled internal standards had <15% RSD, while analytes without matching standards had 15-24% RSD. This method provides an automated means to detect seven fentanyl analogs, and quantitate four fentanyl analogs with the benefits of DBS at levels anticipated from an overdose of these potent opioids.