Assessment of dried blood micro-sampling methods for oxylipin analysis in newborn blood using UPLC-MS/MS

Conventional sampling methods for clinical analysis make use of plasma or serum and require large blood volumes, cold storage, and specialized handling. This renders them impractical and invasive, especially when dealing with vulnerable groups of patients and the analysis of low-abundant and unstable compounds such as oxylipins. Dried blood micro-sampling methods are designed for collecting minimally invasive small-volume blood samples (<100 μL), providing advantages in stability, handling, and storage. The aim of this study is to develop and compare micro-sampling approaches that can be readily implemented in clinical analysis circumventing the barriers of conventional sampling methods. (96) RESULTS: This study assessed the performance of Pre-Cut Dried Blood Spots (PCDBS) and Volumetric Absorptive Micro-Sampling (VAMS®) devices for determining oxylipins, using small-volume liquid whole blood sampling as reference. A Liquid Chromatography - tandem Mass Spectrometry method was successfully developed and validated. Both PCDBS and VAMS® were prepared using 30 μL of spiked blood and dried for 2 h before extraction and analysis. Optimal results were achieved by pre-treating devices with antioxidant before sample deposition and avoiding the internal standard to undergo evaporation steps during preparation of micro-sampling devices. Long-term storage effects were assessed over a three-month period, and the micro-sampling devices were tested on umbilical cord blood samples from 35 newborns. For PCDBS and VAMS®, eight and nine oxylipins, respectively, showed comparable results to those obtained from liquid whole blood samples with mean concentrations ranging between 0.7 and 6.3 nM (140) SIGNIFICANCE: This study is the first to analyse oxylipins in umbilical cord blood using VAMS® and PCDBS micro-sampling devices, demonstrating their effectiveness for quantification at nM concentrations. It highlights the impact of sample collection, storage, and internal standard handling on lipid profiles. Stability is critical and cold storage (-20 °C) is mandatory. Future research focusing on the standardization of protocols for comparability among laboratories and enhancing sensitivity with improved LC-MS/MS techniques to expand accessible oxylipins are needed. (75).