Final ProgramCPSA 2011
Science and Technology Coming Together to Make a Difference
October 3 - 6, 2011
Bucks County Sheraton Hotel
Langhorne, PA
Poster Abstract #06
Comprehensive Study Examining Interfering Compounds from Various Dried Blood Spot Cards and Extraction Solvents with ESI Positive Tandem Quadrupole MS
1) Waters Corporation, Milford, MA USA; 2) GlaxoSmithKline, King Of Prussia, PA USA; 3) Imperial College, London, United Kingdom
Dried Blood and Plasma Spots (DBS) in rodents eliminate any terminal procedures necessary for adequate sample volume and also supports use of fewer animals, better data quality, and cost-savings in shipping and storing samples. However, potential interferences may arise from these cards including the additives that denature proteins, lyse cells, and stabilize DNA. This study illustrates the most common interferences seen from a variety of cards and extraction solvents.
DBS cards (Whatman DMPK-A, DMPK-B, DMPK-C and 903) were investigated. Methanol, acetonitrile, water, formic acid and zinc sulfate in varying combinations were used for extraction. Methyl-tert-butyl ether and acetone: acetonitrile were also tested to simulate liquid-liquid extractions (LLE). Cards (blank or spotted) were punched followed by addition of solvents, vortex-mixed, and centrifuged. The supernatant was transferred directly into injection vials. For LLE, the supernatant was transferred, evaporated and then reconstituted with methanol: water. Samples were then injected onto an UPLC column and eluted using a linear gradient followed by MS using a tandem quadrupole MS operating in positive electrospray mode.
The extracted samples from different cards showed differences in the spectra when analysed by MS scan over the range of 100 - 1000 m/z. Each card type showed unique patterns of interfering ion transitions and the noted transitions and retention times varied based on the organic mobile phase. All card types showed identical spectra of biological interferences based on matrix. For extraction solvents containing water, increased matrix components were observed compared to solvents without water. Multiple punches taken from each individual card type and punches from multiple cards showed no discernable variation in results. It is important to identify regions of potential interference with the analyte(s) of interest to avoid ion suppression and ensure overall reproducibility of an assay. DBS shows decreased abundance of biological interferences leading to improved assay reproducibility. Considering each card type provides a unique set of interfering transitions and differences based on mobile phases, it is possible to choose a particular card based on the known retention time of the analyte(s).
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