Accurate weighing and dilution-assisted plasma microsampling (AWADA-PM): an easy-to-implement and rugged strategy

Background: Liquid microsampling can realize ethical benefits through reduced animal usage. It inherently deals with a minute amount of sample; for example, <30 mu l of plasma, which is generally insufficient for multiple analyses. Results: We report accurate weighing and dilution-assisted plasma microsampling (AWADA-PM) that substantially increases sample sizes (e.g., by tenfold). Plasma samples are harvested from blood samples (similar to 70 mu l) in capillaries. The plasma samples are weighed with a calibrated balance. The weights are converted to volumes using a standard plasma density of 1.025 g/cm(3). Diluent is added with a calibrated pipette to the harvested plasma to achieve a tenfold dilution. Conclusion: The proof-of-concept for AWADA-PM was successfully demonstrated for the quantitation of acetaminophen in rat plasma (K(2)EDTA) using liquid chromatography-tandem mass spectrometry employing water and blank rat plasma as diluents. The results clearly demonstrate that the AWADA-PM strategy is an easy-to-implement and reliable microsampling technology that has potential for full regulatory compliance.