In Situ Hydrothermal Growth of Metal−Organic Framework 199 Films on Stainless Steel Fibers for Solid-Phase Microextraction of Gaseous Benzene Homologues

Abstract

Metal-organic frameworks (MOFs) have received great attention due to their fascinating structures and intriguing potential applications in various fields. Herein, we report the first example of the utilization of MOFs for solid-phase microextraction (SPME). MOF-199 with unique pores and open metal sites (Lewis acid sites) was employed as the coating for SPME fiber to extract volatile and harmful benzene homologues. The SPME fiber was fabricated by in situ hydrothermal growth of thin MOF-199 films on etched stainless steel wire. The MOF-199-coated fiber not only offered large enhancement factors from 19,613 (benzene) to 110,860 (p-xylene), but also exhibited wide linearity with 3 orders of magnitude for the tested benzene homologues. The limits of detection for the benzene homologues were 8.3-23.3 ng L(-1). The relative standard deviation (RSD) for six replicate extractions using one SPME fiber ranged from 2.0% to 7.7%. The fiber-to-fiber reproducibility for three parallel prepared fibers was 3.5%-9.4% (RSD). Indoor air samples were analyzed for the benzene homologues using the SPME with the MOF-199-coated fiber in combination with gas chromatography-flame ionization detection. The recoveries for the spiked benzene homologues in the collected indoor air samples were in the range of 87%-106%. The high affinity of the MOF-199-coated fiber to benzene homologues resulted from the combined effects of the large surface area and the unique porous structure of the MOF-199, the pi-pi interactions of the aromatic rings of the analytes with the framework 1,3,5-benzenetricarboxylic acid molecules, and the pi-complexation of the electron-rich analytes to the Lewis acid sites in the pores of MOF-199.

Development of Novel Solid-Phase Microextraction Fibers

“…MOF-199 was the first reported MOF utilized as an SPME fiber coating material. It was immobilized on etched stainless wire via an in situ hydrothermal method [148]. This homemade fiber exhibited wide linear ranges, low detection limits, high enrichment factors, and higher extraction efficiencies than the commercial SPME/DVB fiber with benzene homologues as the target analytes.…”

“…Cui et al [148] observed that humidity decreased the extraction efficiencies, since the coordination structure would be unstable under certain humidity. Some MOFs are stable to humidity and water, such as MIL-53 [156] and [Cd(L) 2 (ClO 4 ) 2 ]ÁH 2 O (L = 4-amino-3,5-bis(4-pyridyl-3-phenyl)- [157], which were used for DI SPME in aqueous solutions.…”

Preparation and evaluation of mesoporous cellular foams coating of solid-phase microextraction fibers by determination of tetrabromobisphenol A, tetrabromobisphenol S and related compounds

“…As an efficient and remarkable sample preparation technique, solidphase microextraction (SPME) has attracted increasing attention due to its high efficiency, simplicity, solvent-free and facilitation in automation and coupling techniques [2][3][4]. In general, the fiber coating is considered to be the key factor in SPME technique [5][6][7]. Till now, the varieties of commercially available SPME fibers are increasing.…”

“…For new coating materials, high-porosity materials have attracted much attention recently because of their large specific surface areas and high extraction capacities resulting in significant improvement in sensitivity, such as carbon nanotubes [15], graphene [16,17] and metal-organic framework [7]. Mesoporous materials are considered the high-efficiency sorbents due to high specific surface area, controllable pore size, narrow pore size distribution, thermal and mechanical stability, which have various applications in chemical industry [18,19], environment [10,[18][19][20], medicine [21,22], adsorption and separation [23].…”

Polypyrrole/graphene composite‐coated fiber for the solid‐phase microextraction of phenols

“…Although these commercial fibers have been successfully applied in many fields, some of them still have drawbacks, such as high cost, nonresistance to high temperature and organic solvents, low extraction efficiency (especially for polar and ionic compounds), and selectivity, etc. To overcome these disadvantages, new SPME coatings with remarkable properties have been developed continually using new preparation methods, including direct use of uncoated fibers [8], sol-gel technology [9], epoxy-glued solid sorbents [10], electrochemical modification [11] and physical deposition [12], or new materials [13,14].…”