Dual-functional SiO₂@Cr₂O₃-C₁₈ sorbent combining Lewis acid-base and hydrophobic interactions for the selective...

The growing concern of perfluoroalkyl substances (PFAS), or "forever chemicals," with serious health implications across the globe necessitates the development of sophisticated analytical techniques for the sensitive analysis of these compounds in biological samples. However, the critical limitations of common SPE sorbents in terms of low selectivity, poor recoveries in biological samples containing high protein content, and high susceptibility to matrix effects in the form of ion suppression have hindered the analysis of these compounds. To overcome these problems, a new dual-functional sorbent was synthesized using a novel composite material consisting of chromia nanoparticles (Cr₂O₃) and hydrophobic octadecyl chains (C₁₈) on a high-surface-area silica support.

Comprehensive characterization (FTIR, TEM, XPS, BET) confirmed uniform chromia dispersion, successful dense C₁₈ grafting, and high structural stability. Under optimized SPE-LC-MS/MS conditions, the sorbent provided enrichment factors (194-198) for three representative perfluoroalkyl carboxylates (PFHpA, PFOA, PFDoA), yielding ultra-trace limits of detection (LOD) of 25 - 26 ng L^-1. To rigorously evaluate its practical utility, the method was validated in standardized synthetic human plasma. The dual-retention mechanism successfully mitigated protein fouling and severe ion suppression, demonstrating an absolute matrix effect of <15% (representing an >85% reduction compared to the direct injection of untreated plasma). Furthermore, the sorbent exhibited robust operational reusability (>50 extraction cycles with <5% efficiency loss).

The sorbent exhibited an excellent green analytical profile, achieving a Sample Preparation Metric of Sustainability (SPMS) score of 5.16. This scalable and environmentally friendly platform establishes a highly reliable analytical methodology for PFAS trace analysis in complex biological matrices, offering a robust solution for accurate human biomonitoring and exposure assessment.