Pre-analytic assessment of dried blood and dried plasma spots: integration in mass spectrometry-based metabolomics and lipidomics workflow.

Microsampling, especially dried blood spots (DBS), emerged in recent years as a viable alternative to conventional blood collection since it is rapid, simple, minimally invasive, and has user-friendly characteristics. Moreover, DBS are able to avoid analyte degradation thanks to their great stability. Due to their versatility, clinical applications with DBS have increased, including mass spectrometry-based metabolomics and lipidomics studies. In this work, we evaluated and optimized extraction protocols testing five different extraction solutions to perform metabolomics and lipidomics studies on the same spot considering three commercially available microsampling devices, Capitainer, Whatman, and Telimmune. Parallelly, we also evaluated the short-term stability of the three devices at room temperature for up to 5 days. Our results showed that pure methanol was the best compromise to simultaneously extract from the same spot both the lipidome and polar metabolome. However, we also propose a two-step protocol combining methanol and water extraction that improves polar metabolite extraction and shows improved reproducibility in Capitainer and Whatman. Short-term stability results highlighted that both polar metabolites and lipids were stable for up to 6 days using the Capitainer device, while with Whatman and Telimmune, some significant variations were observed after 3 days for some classes of metabolites/lipids, suggesting the need for cold-chain storage when working with these devices.