Dual Functionality in Whole Blood Microsampling: Combining Plasma Separation and Immunoaffinity Cleanup for LC-MS Based Targeted Protein Analysis.

Smart sampling is a concept that combines a traditional microsampling, such as dried blood spot (DBS), with sample preparation initiated at the moment of sampling. In this paper, plasma separation and antibody-based affinity cleanup are integrated into a single 3D-printed sampling device. Our goal was to evaluate and validate the analytical performance of this device for LC-MS-based determination of hCG. The device effectively eliminated red blood cells, significantly reducing hemoglobin interference by more than 93%. Plasma extraction of >80% was achieved from only 20 μL of whole blood. The partial validation in line with the European Medicines Agency's ICH guidelines showed that the analytical performance of the sampling device was not compromised. Linear correlation coefficients ≥0.991 were achieved (range: 0.5-75 ng/mL). High between-run accuracy for all QC levels were achieved, ranging from 90 to 105% with a corresponding precision of ≤11%. In conclusion, the 3D-printed device offers a robust solution to traditional microsampling limitations, potentially and in the future enabling point-of-care diagnostics with the versatility and ease of established DBS methods. The successful integration of plasma separation and smart sampling enhances analytical sensitivity and specificity, representing a promising tool for advancements in clinical bioanalysis.