Determination of benzomercaptans in environmental complex samples by combining zeolitic imidazolate framework-8-based solid-phase extraction and high-performance liquid chromatography with UV detection

• Published in: Journal of Chromatography A 2020-11, Vol.1631, p.461580, Article 461580
• Main Authors: Martínez-Pérez-Cejuela, Héctor, Mompó-Roselló, Óscar, Crespí-Sánchez, Neus, Palomino Cabello, Carlos, Catalá-Icardo, Mónica, Simó-Alfonso, Ernesto F., Herrero-Martínez, José Manuel
• Format: Article
• Language: English
• Subjects: Environmental pollutants; Metal-organic frameworks; Sample preparation; Soil and aqueous samples; Solid-phase extraction; Sorbent
• ISSN: 0021-9673
• DOI: 10.1016/j.chroma.2020.461580

•Modulated synthesis of ZIF-8 MOFs with n-butylamine was done.•NH2-ZIF-8-BA 1 as SPE sorbent gave high extraction performance for benzomercaptans.•The MOF had large surface area, hydrophilicity and enhanced adsorption capacity.•SPE/LC method provided low LODs and satisfactory sorbent reusability.•The method was successfully applied to complex environmental samples. In this work, the synthesis of zeolitic imidazolate framework-8 (ZIF-8) crystals and their subsequent application as effective sorbents for extraction and preconcentration of several benzomercaptans from environmental complex samples is described. These materials were prepared by solvothermal approach varying the concentration of n-butylamine modulator to modify the surface of the metal-organic framework. The resulting materials were characterized by scanning and transmission electron microscopy, powder X-ray diffraction and Fourier transform infrared spectroscopy. The ZIF-8 material that gave the best features was selected as extractive phase and the influence of various parameters (sample pH and elution solvent composition, among others) on the extraction efficiency of target compounds were investigated. Under the optimal conditions of the method, the tested analytes (2-mercaptobenzothiazole, 2-mercaptobenzoxazole and 2-mercapto-6-nitrobenzothiazole) were retained and eluted quantitatively with alkaline 50:50 (v:v) methanol-water mixture. Using the proposed method, low limits of detection, in the range of 16–21 ng L−1 for aqueous samples and 0.4–0.5 µg kg−1 for soil samples, were achieved whereas the precision (expressed as relative standard deviation) was lower than 7%. The resulting solid-phase extraction protocol, using the zeolitic material as sorbent, was combined with liquid chromatography and ultraviolet-vis detector and successfully applied to determine traces of these organic pollutants in environmental samples.