In situ fabricated porous carbon coating derived from metal-organic frameworks for highly selective solid-phase microextraction.

Solid-phase microextraction (SPME) has been widely used in analysis of trace organic contaminants in environmental samples. Stable, efficient, and selective fiber coating is the key to the development of SPME technique. In this study, an in situ fabricated porous carbon coating that derived from metal-organic frameworks (MOFs) was introduced for solid-phase microextraction (SPME). The carbon coating (denoted as MOF-74-C) was prepared by the direct carbonization of a MOF-74 coating that was in situ grown on stainless steel wire, which was explored for the extraction of odorous organic contaminants for the first time. MOF-74-C coated fiber showed high extraction efficiency (1.1-16.0 times larger than commercial fibers for most tested analytes under the same extraction conditions), as well as good thermal and chemical stability. Furthermore, it can selectively extract the analytes with the simultaneous exclusion of coexisting dissolved organic matter due to the molecular sieve effect invoked by the well-defined micropores. The method based on MOF-74-C coating for analysis of odorants afforded wide linear ranges (more than two orders of magnitude), low detection limits (below the odor threshold concentrations), good intra- and inter-day accuracies (90.1-107.3%) and precisions (relative standard deviations/RSDs below 9.4%) and satisfactory reproducibility (RSDs below 8.7%). Finally, the MOF-74-C coated fiber was successfully applied for the SPME analysis of odorants in real water samples. These results highlight the great potential of in situ fabricated porous carbons derived from MOFs for SPME applications.