“…In contract, no apparent impact of blood volume has been seen in several recent LC-MS/MS applications for quantitative analysis of small molecules, e.g. acetaminophen (Spooner et al, 2009), tacrolimus (Hoogtanders et al, 2007), vincristine and actinomycin-D (Damen et al, 2009), dextromethorphan and dextrorphan (Liang et al, 2009) and some antiviral drugs (ter Heine et al, 2008Heine et al, , 2009a, in DBS samples. Nonetheless, during developing a DBS-LC-MS/ MS method, the relationship between dried blood spot area/ weight and the amount of blood spotted on the paper/card should be examined by spotting increasing volumes of blood onto the paper/card (at least in duplicate) and measuring the areas of the obtained spots (ter Heine et al, 2008) or weighing the obtained spots (Hoogtanders et al, 2007).…”