Current Strategies for Coping with The Hematocrit Problem in Dried Blood Spot Analysis

The hematocrit (Hct) problem is the most widely discussed issue in dried blood spot (DBS) analysis. As Hct determines the vis-cosity of blood, it affects the spreading of blood spotted on filter paper. Therefore, par -tial punches taken from DBS prepared from blood with different Hct values will contain different amounts of blood. Hence, depend-ing on the analyte of interest and the filter paper used, deviating Hct values may cause significant assay bias. Hct may additionally influence the potential bias introduced by the site of punching, the recovery of a par-ticular compound from DBS and/or have an impact on matrix effects. As a consequence, the Hct effect is generally recognized as the most important factor hampering the wide-spread application of DBS