When using dried blood spot (DBS) sampling for the quantitative bioanalysis of circulating concentrations of drugs, metabolites and endogenous analytes, it is important that a fixed volume of blood is deposited to overcome the issues associated with blood hematocrit (HCT) and homogeneity. The volumetric performance of the KTH DBS collection device was tested with radiolabelled [14C]-diclofenac. It was demonstrated that the device deposits a fixed volume of blood (13.5 μL) regardless of the HCT (25–65%), or lipid content of the blood sample. Further, it was found that the precision and accuracy of the derived dried blood samples were at least as good as those of a positive displacement pipette. The device was found to be easy to use and gave acceptable dried samples for 92.9% of the tests performed (n = 42).