Dried blood spot sampling is used frequently in the screening of neonates. This method involves collecting of 15–30 uL of whole blood on blotting paper. A standard hole punch is then used to cut discs of whole blood from the paper. One or more discs are placed into an elution buffer for a period of time and are subsequently analyzed much in the way that plasma or serum would be. Given the small blood volumes needed for dried blood spot sampling, this method has become an attractive tool in pre-clinical and clinical PK studies. Among pediatric researchers, it is especially appealing as a potential means for overcoming blood volume limitations in infants and children.