Validation of a dried blood spot LC-MS/MS approach for cyclosporin A in cat blood: comparison with a classical sample preparation.

A rapid, selective and sensitive bioanalytical method was developed and validated for cyclosporin A (CsA) in cat blood samples using dried blood spot (DBS) coupled with high pressure liquid chromatography hyphenated to positive electrospray tandem mass spectrometry (HPLC-ESI-MS/MS). CsA was quantified using a structural analog cyclosporin D (CsD) as internal standard in multiple reaction monitoring mode (MRM) using the transitions 1220→1203 for CsA and 1234→1217 for CsD. A 5-μL blood aliquot was spotted onto a DBS card, then after a drying step, blood spots were punched out from the cards and extracted with MeOH before injection into a LC-MS/MS system.