Investigation of endogenous blood lipids components that contribute to matrix effects in dried blood spot samples by liquid chromatography-tandem mass spectrometry.

Dried blood spot (DBS) sampling coupled to liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a rapidly developing approach in the field of biopharmaceutical analysis. DBS sampling enables analysis of small sample volumes with high sensitivity and selectivity while providing a convenient easy to store and ship format. Lipid components that may be extracted during biological sample processing may result in matrix ionization effects and can significantly affect the precision and accuracy of the results. Glycerophosphocholines (GPChos), cholesterols and triacylglycerols (TAG) are the main lipid components that contribute to matrix effects in LC-MS/MS. Various organic solvents such as methanol, acetonitrile, methyl tertiary butyl ether, ethyl ether, dichloromethane and n-hexane were investigated for elution of these lipid components from DBS samples. Methanol extracts demonstrated the highest levels of GPChos whereas ethyl ether and n-hexane extracts contained less than 1.0 % of the GPChos levels in the methanol extracts. Ethyl ether extracts contained the highest levels of cholesterols and TAG in comparison to other investigated organic solvents. Acetonitrile is recommended as an elution solvent due to low lipid recoveries. Matrix effects resulted from different extracted lipid components should be studied and assessed carefully in DBS samples.