The Development of Dry Plasma Spot Analysis and a Comparison with Dry Blood Spots and Conventional Plasma Bioanalysis using Methylene Blue

Introduction
Anyone reviewing the hottest buzzwords in bioanalysis over the last few years could not escape the phrase ’Dry Blood Spot’ or DBS. The advantages of the technique have been tirelessly championed by Matt Barfield and
Neil Spooner of GSK and dry blood spots have been the subject of countless scholarly articles, conference presentations and will even be the subject of its own dedicated conference [1] when the European Bioanalysis
Forum hold the EBF workshop “Connecting Strategies on Dried Blood Spots” in Brussels on the 17 - 18 June 2010.

The use of dried blood spots on filter paper blood sampling is a well established technique for the screening of in-born errors of metabolism [2,3]. The physics of blood dispersion on the filter paper limit the amount
of matrix that can be practicably stored and sub-sampled using a dried blood spot. For many years this limitation prohibited the use of dried blood spots by the bioanalytical community for the development of pharmaceuticals. This was primarily because the required assay detection levels could not be achieved. The benefits of DBS are well documented in numerous publications [4,5,6]; in recent years the relentless improvements in separation and detection techniques have allowed DBS to be considered by bioanalysts as a practical alternative to ‘wet’ plasma. The technique is rapidly becoming established in bioanalysis, especially in Europe, although it is still in its infancy for pharmaceutical development. Significant developments in workflow automation are still required.