Sensitive determination of a drug candidate in dried blood spots using a TLC–MS interface integrated into a column-switching LC–MS/MS system

Abstract

Background: A thin-layer chromatography–mass spectrometry interface was previously reported to extract compounds from dried blood spots online. Here, we integrated this interface into a column-switching LC–MS/MS system for online solid-phase extraction and addressed internal standard addition. Results: A drug was analyzed in dried blood spots with a lower limit of quantitation of 50 pg/ml. The internal standard was added via an autosampler to the extraction solvent. The method featured online aqueous dilution of the dried blood spots extract with subsequent trapping and gradient analytical separation. Good precision, accuracy and recovery were obtained. Conclusion: The thin-layer chromatography–mass spectrometry interface provided high reproducibility and good extraction efficiency. Although manually operated, it significantly reduced sample preparation efforts. The combination with online solid-phase extraction allowed enrichment of larger sample/extract volumes and efficient clean-up.