A simple dispersive micro-solid phase extraction method based on magnetic MIL-101(Cr)@MWCNTs for the simultaneous determination of phthalates and parabens

Phthalic acid esters (PAEs), widely known are phthalates, are among the compounds that are attracting a high interest nowadays as a result of the high production of plastics wordwide. In this sense, PAEs are widely used as plasticizers in the manufacture of plastics to provide the necessary flexibility for their correct handling. Apart from that, they also have an extensive variety of industrial, agricultural and domestic applications [1]. The analysis of PAEs in food matrixes has attracted much attention because of their potentional risk for humans’ health, including fertility and growth problems [2]. In particular, their analysis in drinking water or beverages, especially those commercialized in plastic bottles, is of importance as a result of the high human consumption and their already mentioned negative effects for health [3]. Parabens (alkyl and aryl esters of p-hydroxybenzoic acid) are a group of widely used ingredients that act as an antifungal and preservation agent in processed food, cosmetics, and pharmaceuticals. Owning to their attractive features such as broad-spectrum, antimicrobial activity, low cost, water solubility, and chemical and thermal stability in a wide pH range, parabens are popular preservatives in consumer products. The extensive applications of parabens containing compounds have increased worldwide concerns about them because of their potential to disrupt endocrine function. Furthermore, parabens have been found in a small number of breast tumor tissues. Thus, some simple, sensitive, and fast methods are needed to determine trace amounts of parabens in different matrices [4]. In this study, an easy and fast dispersive micro-solid phase extraction (D-µ-SPE) method was developed for coextraction of target analytes. Magnetic MIL-101(Cr)@MWCNTs was synthesized and used as an efficient sorbent in D-µ-SPE method. The synthesis of MOF was confirmed by Fourier transform infrared spectroscopy, X-ray dispersive spectroscopy, thermogravimetry analysis, scanning electron microscopy, transition electron microscopy, vibrating sample magnetometry and X-ray diffraction. The method is easily operated, benefits from good reproducibility values, low detection limit with wide dynamic linear range, and acceptable extraction recovery. Due to the magnetic property, the phase separation was convenient and rapid for D-µ-SPE procedure. The opted conditions were: pH of the sample, 8; MOF amount, 11.5 mg; sorption time, 13.5 min; salt concentration, 10% w/v; sample volume, 18 mL; type and volume of the eluent, acetonitrile, 100 µL; elution time; 2 min. Under the optimum conditions detection limits and linear dynamic ranges were obtained in the range of 0.12-0.43 µg L−1 and 0.5-1000 µg L−1, respectively. Relative standard deviations (n = 5) were in the range of 1.5%-5.6%. Eventually, the synthesized magnetic MOF was successfully applied for the coextraction and determination of target analytes in various real samples with satisfactory results.