Recent Advances in Affinity MOF-Based Sorbents with Sample Preparation Purposes.

This review summarizes the recent advances concerning metal-organic frameworks (MOFs) modified with several biomolecules (e.g., amino acids, nucleobases, proteins, antibodies, aptamers, etc.) as ligands to prepare affinity-based sorbents for application in the sample preparation field. The preparation and incorporation strategies of these MOF-based affinity materials were described. Additionally, the different types of ligands that can be employed for the synthesis of these biocomposites and their application as sorbents for the selective extraction of molecules and clean-up of complex real samples is reported. The most important features of the developed biocomposites will be discussed throughout the text in different sections, and several examples will be also commented on in detail.

Bio-metal-organic frameworks for molecular recognition and sorbent extraction of hydrophilic vitamins followed by their determination using HPLC-UV.

A bio-metal-organic framework (bio-MOF) derived from the amino acid L-serine has been prepared in bulk form and evaluated as sorbent for the molecular recognition and extraction of B-vitamins. The functional pores of bio-MOF exhibit high amounts of hydroxyl groups jointly directing other supramolecular host-guest interactions thus providing the recognition of B-vitamins in fruit juices and energy drinks. Single-crystal X-ray diffraction studies reveal the specific B-vitamin binding sites and the existence of multiple hydrogen bonds between these target molecules and the framework. It offered unique snapshots to accomplish an efficient capture of these solutes in complex aqueous matrices. Four B-vitamins (thiamin, nicotinic acid, nicotinamide, and pyridoxine) were investigated. They were eluted from the sorbent with phosphate buffer at pH 7 and analyzed by HPLC with UV detection. The sorbent was compared with commercial C18 cartridges. Following the procedure, acceptable reproducibility (RSD values < 14%) was achieved, and the detection limits were in the range 0.4 to 1.4 ng mL-1. The method was applied to the analysis of energy drink and juice samples and the recoveries were between 75 and 123% in spiked beverage samples. Graphical abstractA bio-MOF as SPE sorbent was prepared and applied to the extraction of B-vitamins in fruit juices and energy drinks.

Incorporation of metal-organic framework amino-modified MIL-101 into glycidyl methacrylate monoliths for nano LC separation.

Metal-organic frameworks consisting of amino-modified MIL-101(M: Cr, Al, and Fe) crystals have been synthesized and subsequently incorporated to glycidyl methacrylate monoliths to develop novel stationary phases for nano-liquid chromatography. Two incorporation approaches of these materials in monoliths were explored. The metal-organic framework materials were firstly attached to the pore surface through reaction of epoxy groups present in the parent glycidyl methacrylate-based monolith. Alternatively, NH2 -MIL-101(M) were admixed in the polymerization mixture. Using short time UV-initiated polymerization, monolithic beds with homogenously dispersed metal-organic frameworks were obtained. The chromatographic performance of embedded UV-initiated composites was demonstrated with separations of polycyclic aromatic hydrocarbons and non-steroidal anti-inflammatory drugs as test solutes. In particular, the incorporation of the NH2 -MIL-101(Al) into the organic polymer monoliths led to an increase in the retention of all the analytes compared to the parent monolith. The hybrid monolithic columns also exhibited satisfactory run-to-run and column-to-column reproducibility.