The first reply to the first comment was mine - I just realized you should sign your name.
In regard to Dr. Guthrie and DBS - I do think that he started something that will only expand its use with time. A DBS is much more than a newborn screening matrix platform. My colleagues in mass spectrometry view it as a clean up step where an organic extraction leaves inorganic salts behind. In fact, even if I were to use classical isotope dilution methods in mass spectrometry (where you add a labeled standard to a liquid and remove the quantitative errors of the DBS) I still find that there are advantages to spotting the sample which contains the standards on paper as I get better ionization of the metabolites I am interested in.