Impact of Sampling Paper/Cards on Bioanalytical Quantitation via Dried Blood Spots by Liquid Chromatography-Mass Spectrometry

Dried blood spots (DBS) on paper as a sampling technique in newborn screening has been widely adopted by bioanalytical chemists for preclinical and clinical sample collection. DBS is based on the assumption that single size punch of DBS absorbs the same volume of blood regardless of physiological differences derived from test subject genders, disease states, nutrition, or hydration affecting blood viscosity, although it is well known that such differences have a fundamental impact on the quantitation accuracy of DBS as a sampling technique. There are multiple types of sampling media in either plain filter paper or chemically treated paper/cards available for DBS applications. Pretreated paper/cards contain chemicals such as denaturants, surfactants, and/or chelating agents to deactivate pathogens, enzymes and prevent the growth of biological organisms. In this chapter, the chemical constituents of various paper/cards are explored. The impact of paper/card type on analytical interference, evenness of DBS spots, and radial distribution of analyte are evaluated. The paper/card impact on the matrix effect was studied. It was found that the impregnated chemicals on the pretreated DBS paper/cards could be more than 50 % of the total paper/card weight. These water-soluble chemicals make the analyte distribution unpredictable across the dried blood spots and can interfere with LC-MS. Six compounds across a large Log D range were used to evaluate different types of paper/cards for understanding the impact of the sampling paper/cards on DBS quantitation accuracy. The results indicate that the impact is significant and an evaluation of sampling paper/card impact is necessary for most compounds.