Finger-prick blood sampling using volumetric absorptive microsampling (VAMS) method for monitoring the main (poly)phenolic metabolites in human blood after barley biscuit intake

Abstract

A novel method based on volumetric absorptive micro-sampling (VAMS) combined with UPLC-MS/MS was developed and validated to determine the principal (poly)phenolic metabolites in human blood following the consumption of 140 g of purple whole-grain barley (WGB) biscuits. Finger-prick blood samples were collected from 11 healthy volunteers at multiple time points up to 48 h post-ingestion. To extract (poly)phenolic metabolites efficiently, various extraction parameters were optimized. Then, the method was successfully applied and five colonic (poly)phenolic metabolites from the main (poly)phenolic families from barley were detected: benzene-1,2-diol-O-sulphate, 3-(4 ′-hydroxy-3 ′-methoxy)propanoic acid and its sulphated form, 5 ′-(3 ′ ,4-dihydroxyphenyl)-γ-valerolactone-O-sulphate, and methyl luteolin-O-glucuronide. Maximum absorption occurred at 12 h for most metabolites, while luteolin-O-glucuronide showed two distinct peaks at 2 and 6 h, indicating its dual-phase absorption. Comparison with venous plasma samples collected during the 0–6 h period showed no significant differences (p > 0.05), validating the statistical reliability of VAMS as an alternative to venipuncture. Thus, VAMS emerges as a less invasive and statistically robust means for analyzing the pharmacokinetic profile of (poly)phenols, particularly those arising from colonic metabolism.

This study was supported by the Spanish Ministry of Industry, Economy and Competitiveness, the Agencia Estatal de Investigación (AEI) and the European Regional Development Fund (ERDF) through the PID2020-113009RB-100 INNOBAR project and by the Generalitat de Catalunya through the Maria Engracia Cortijo predoctoral FI SDUR grant. Silvia Yuste has a Margarita Salas postdoctoral grant funded by the European Union – NextGeneration EU through the Ministerio de Universidades and the Universitat de Lleida.