Application of novel plasma separation filter cards for quantification of nucleoside/nucleotide reverse transcriptase inhibitor di/triphosphates in dried blood spots using LC–MS

BACKGROUND: A rapid and sensitive LC–MS method has been developed and validated for the quantification of nucleoside di/triphosphates using a novel plasma separation card (HemaSep). MATERIALS & METHODS: Cards were spotted with whole blood and stored at -80°C. Metabolites were extracted using 70:30 MeOH:20% formic acid, followed by weak anion exchange SPE and eluted using a Biobasic-AX column. Quantification was performed using a triple quadrupole mass spectrometer with a calibration range of 1.25–250 pmol/sample. RESULTS: The recovery of metabolites was high (>93%). Precision and accuracy were acceptable and metabolites remained stable on the card after 29 days (stored at ambient temperature). CONCLUSION: HemaSep dried blood spots are a useful microsampling tool and offer an alternative to liquid plasma as they maintain stability over time.