Versatile injector for inline renewable solid-phase extraction: Application to cyclodextrin-based bioaccessibility assessment in environmental solids

Abstract

[eng] We present a new flowpath for a liquid chromatographic injector to perform inline micro-solid phase extraction. The sample is processed at real time trapping the analytes and discarding the matrix. Cleaning the matrix and injecting 10 µL of sample takes 70 s, comparable with the injection in commercial HPLC systems. If the aim is to preconcentrate the analytes, average enrichment factors of 250 have been obtained after processing volumes of 3200 µL in 16 min (interleavable with the chromatographic step), keeping the peak position and width independent of the injected volume (compared to large volume direct injection).</p><p>The desired bed mass is automatically and pressure-driven manipulated in the valve, retained by an inline frit, and optionally, after the analysis, removed by forward flow.</p><p>The chromatographic performance of the new design is compared to the standard 6-port, 2-position injector. As an application example, we monitored the extraction kinetics of a bioaccessibility extraction test of organic contaminants in soil, by extracting several fractions in valve, process them with SPE with a balanced hydrophilic-hydrophobic reversed-phase sorbent and inject them into HPLC. Aiming at avoiding carryover, the 3 mg sorbent bed was exchanged before every run. It should be noted that this contribution focuses on HPLC, but other non-separative techniques, such as Flow Injection Analysis, can equally benefit from this injection platform.</p>