Elsevier

Food Chemistry

Volume 355, 1 September 2021, 129411
Food Chemistry

Collaborative compounding of metal–organic frameworks for dispersive solid-phase extraction HPLC–MS/MS determination of tetracyclines in honey

https://doi.org/10.1016/j.foodchem.2021.129411Get rights and content

Highlights

  • Collaborative compounding of MOFs for dispersive solid-phase extraction.

  • A high-efficiency purification and extraction of tetracyclines in honey.

  • Sensitive determination of tetracyclines by HPLC–MS/MS.

Abstract

Metal-organic frameworks (MOFs), a sort of dispersive solid-phase extraction (d-SPE) material, has shown considerable prospects in the pretreatment of food, biological and other complex samples. Herein, we developed a method for compounding MOFs for d-SPE and trace determination of tetracyclines (TCs) in honey. When the compounding ratio of MIL-101 (Cr), MIL-100 (Fe) and MIL-53 (Al) was 7:1:2, adsorption–extraction was effective. Followed by high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS), the limits of detection were 0.073–0.435 ng/g and the limits of quantitation ranged from 0.239 to 1.449 ng/g for oxytetracycline, tetracycline, chlortetracycline and doxycycline. The method was applied to four kinds of honey samples with recoveries from 88.1% to 126.2%. The compounding of MOFs provides a strategy for purification and multi-target extraction from complex food matrices by d-SPE.

Introduction

Bees are prone to bacterial diseases and are often fed antibacterial drugs. Tetracyclines (TCs), a group of low-cost and broad-spectrum antibiotics, are widely used as veterinary medicines for their antibacterial activity against both gram-positive and gram-negative bacteria (Koesukwiwat, Jayanta, & Leepipatpiboon, 2007). Commercial beekeepers have traditionally used antibacterial drugs for the control of bee diseases. In particularly, TCs are abused as a treatment or preventive measure for infectious American and European foulbrood (Reybroeck, Ooghe, Brabander, & Daeseleire, 2007). Therefore, TCs may accumulate in the bee and become a harmful contaminant in honey. Excessive exposure to TCs may cause allergic reactions, gastrointestinal disturbances and tetracycline teeth pigmentation in humans (HAKUTA et al., 2009, Pastor-Navarro et al., 2009).

The determination and control of TCs residual in honey is of great significance. Many countries and regions have stipulated maximum residue limits (MRL) of TCs in honey, such as 50 μg/kg in China, 20 μg/kg in the European Union, and 10 μg/kg in the United States (Khong et al., 2005, Xu et al., 2008). In Switzerland, TCs are banned in honey products (Zhang, Li, Li, Zhang, Gao, & Li, 2019). In order to detect TC residues in honey, it is urgent to establish a convenient and effective method.

High-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) has good selectivity and sensitivity for trace organic contaminants, such as pesticide and veterinary drug residues including TCs (Bogialli and Corcia, 2009, Huang et al., 2019, Tuzimski and Petruczynik, 2020). Indeed, this technique requires sample pretreatment, including clean-up samples, isolating and enrich analytes from sample matrix. The extraction of TCs from honey is a key step for determination by HPLC–MS/MS. In recent years, the pretreatment methods of TCs include dispersive liquid–liquid microextraction, solid-phase extraction and magnetic solid-phase extraction (Gao et al., 2017, He et al., 2019, Kaewsuwan et al., 2017). However, little attention has been devoted to dispersive solid-phase extraction (d-SPE). d-SPE can be easily modified, and its steps are all relatively straightforward, making it simple, fast, effective and user-friendly. Extraction of hundreds of pesticides with high recovery rate from various food products has been consistently achieved by d-SPE (Kim et al., 2019, Tuzimski and Rejczak, 2016). In principle, the extraction efficiency of d-SPE mainly depends on the type of adsorbent. Currently, polymer (Koseoglu, Ulusoy, Yilmaz, & Soylak, 2020), silica (Islas, Ibarra, Hernandez, Miranda, & Cepeda, 2017), carbon-base materials (Zacs, Rozentale, Reinholds, & Bartkevics, 2018), zirconium dioxide-based materials (Tuzimski & Rejczak, 2017) and magnetic composites (Giakisikli & Anthemidis, 2013) are used as d-SPE adsorbents. Alternatively, metal–organic frameworks (MOFs), porous polymers formed by self-assembly of numerous metal ions and organic ligands with various properties, provide a tremendous advantage in d-SPE, due to their diversity and excellent performance (Gu et al., 2012, Wang et al., 2018).

There are a range of choices of MOFs for screening and compounding suitable adsorbents for targets. Messner et al. (2013) first presented Er-MOF as a d-SPE sorbent for the enrichment of phosphopeptides based on immobilized metal ion affinity chromatography methodology in 2013. After comparing five kinds of MOFs, Rocío-Bautista et al. (2018) found that MIL-53 (Al) as adsorbent of d-SPE can successfully adsorb pollutants with completely different properties, such as hormones in sewage.

Most d-SPE phases in food samples are pretreated utilizing single MOF. Due to the difference of interaction between the targets and the adsorbents, the extraction and recovery of several analytes simultaneously cannot be guaranteed (Islas, Ibarra, Hernandez, Miranda, & Cepeda, 2017). Compounding adsorbents with different adsorption properties can complement each other and further comprehensively improve the extraction and recoveries of the targets. To the best of our knowledge, compounding of MOFs as adsorbents has not been reported for d-SPE in food.

TCs have a common chemical structure with several modifiable sites and a conjugated system (Ibarra, Rodriguez, Miranda, Vega, & Barrado, 2011). Herein, 3 MOFs abundant in π system, MIL-101 (Cr), MIL-100 (Fe) and MIL-53 (Al), were compounded for d-SPE of 4 TCs: oxytetracycline (OTC), tetracycline (TC), chlortetracycline (CTC) and doxycycline (DC). The aim of this work was to explore a efficient method for d-SPE of TCs in honey with compounding of MOFs to establish a more sensitive TCs determination method.

Section snippets

Reagents and chemicals

All chemicals were at least of analytical grade. The standards of OTC (96%), TC (97.7%), CTC (99.5%), DC (98.7%) were purchased from Dr. Ehrenstorfer GmbH (Augsburg, Germany), Cr(NO3)3·9H2O was purchased from Shanghai Macklin Biochemical Co., Ltd. (Shanghai, China), Al(NO3)3·9H2O, terephthalic acid, and reduced iron powder were purchased from Shanghai Aladdin Bio-Chem Technology Co., Ltd. (Shanghai, China). Hydrofluoric acid, trimesic acid, N,N-dimethylformamide (DMF), nitric acid, ethanol,

Compounding MOFs for d-SPE

Fig. 1 shows the compounding 3 MOFs as a d-SPE adsorbent to extract and detect 4 TCs in honey. TCs are a group of analogs with similar chemical structures, which have several modifiable sites and a conjugated system. The maximum molecular length of the 4 TCs is about 12.2 Å.

MIL-101 (Cr), MIL-100 (Fe) and MIL-53 (Al) are the same MOF series; however, they have different ligand, crystal structure and pore size, resulting in different adsorption properties. MIL-101 (Cr) is built up from a hybrid

Conclusion

In summary, we developed a reliable d-SPE method based on the collaborative compounding of MIL-101 (Cr), MIL-100 (Fe) and MIL-53 (Al), and combined it with HPLC–MS/MS to determine four TCs in honey. The compounding MOFs adsorbent can improve the detection accuracy and reduce the LOD and LOQ, which provides a methodological basis for using other kinds of compounding MOFs as d-SPE adsorbents in the future. Overall, the proposed method is expected to be applied to the routine extraction and

CRediT authorship contribution statement

Yue-Hong Pang: Conceptualization, Resources, Writing - review & editing, Project administration, Funding acquisition. Zhi-Yang Lv: Conceptualization, Methodology, Formal analysis, Investigation, Writing - original draft. Ji-Cheng Sun: Validation, Investigation, Data curation. Cheng Yang: Conceptualization, Methodology, Investigation. Xiao-Fang Shen: Methodology, Formal analysis, Validation, Investigation, Funding acquisition.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This work was supported by the National Key R&D Program of China (2018YFC1602300), the National Natural Science Foundation of China (21976070, 22076067), and the Fundamental Research Funds for the Central Universities (JUSRP22003).

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