Assessment of the within- and between-lot variability of Whatman™ FTA® DMPK and 903® DBS papers and their suitability for the quantitative bioanalysis of small molecules

Background: To ensure that PK data generated from DBS samples are of the highest quality, it is important that the paper substrate is uniform and does not unduly contribute to variability. This study investigated any within and between lot variations for four cellulose paper types: Whatman FTA((R)) DMPK-A, -B and -C, and 903((R)) (GE Healthcare, Buckinghamshire, UK). The substrates were tested to demonstrate manufacturing reproducibility (thickness, weight, chemical coating concentration) and its effect on the size of the DBS produced, and the quantitative data derived from the bioanalysis of human DBS samples containing six compounds of varying physicochemical properties. Results & discussion: Within and between lot variations in paper thickness, mass and chemical coating concentration were within acceptable manufacturing limits. No variation in the spot size or bioanalytical data was observed. Conclusion: Bioanalytical results obtained for DBS samples containing a number of analytes spanning a range of chemical space are not affected by the lot used or by the location within a lot.