The aim was to evaluate the performance of different microsampling materials in LC–MS-based protein analysis. The evaluated materials were the Volumetric Absorptive MicroSampling (VAMS) device, the pure cellulose sampling material (DMPK-C) and the water-soluble material (carboxymethyl cellulose, CMC), with the main emphasis on VAMS. Six proteins with different physicochemical properties were used as model proteins. A quick and generic sample preparation consisting of extraction/dissolution of the blood spot, tryptic digestion and subsequent matrix precipitation was applied prior to analysis. The recovery from VAMS, compared to DMPK-C, was dependent on the protein analyte: Lower recovery compared to DMPK-C was seen for β-lactoglobulin and myoglobin (74% and 80%, respectively) while higher recovery compared to DMPK-C was seen for cytochrome c and albumin (149% and 197%, respectively). The recovery from CMC was comparable to the recovery from DMPK-C for all proteins except for cytochrome c (76%). Hematocrit bias was evaluated for DMPK-C and VAMS, and the blood hematocrit influenced the protein analysis from both the materials. A preliminary evaluation was performed for VAMS: The correlation coefficient (R2 ≥ 0.983), the accuracy (71–101%) and the precision (RSD ≤ 20%) were determined for blood spiked with the six model proteins.
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