Evaluating and defining sample preparation procedures for DBS LC-MS/MS assays

Background: A defined approach to develop and validate an LC-MS/MS assay using dried blood spot (DBS) samples is of great interest to many scientists who are adopting this technology. We have evaluated three distinct sample preparation procedures of DBS samples for LC-MS/MS assay development. Results: A new term 'elution efficiency' is introduced to evaluate the effectiveness of eluting compounds from the DBS cards into the liquid phase. Three different types of DBS cards were studied as part of the sample preparation procedures. A DBS LC-MS/MS method was developed, qualified and then applied to a toxicokinetics study. Conclusion: Organic extraction and protein precipitation resulted in significant ion suppression and/or enhancement for FTA (R) Classic or FTA (R) Elute cards. Liquid-liquid extraction produced the least ion suppression/enhancement. Both protein precipitation and liquid-liquid extraction effectively eluted the probe compound from the DBS cards under the conditions tested. However, organic extraction by pure solvents resulted in low elution efficiency.