New fluorescent labeling reagent Benzimidazo[2,1-b]quinazoline-12(6H) -one-5-ethylimidazole ester and its application in the analysis of endocrine disrupting compounds in milk by high performance liquid chromatography with fluorescence detection

Synthesis of cyano and ionic dual-functional hypercrosslinked porous polymer for effective adsorption and detection of endocrine disrupting chemicals in milk matrix

Endocrine disrupting chemicals (EDCs) can interfere with the normal function of endocrine system, posing serious risk to human health. The monitoring of EDCs in foods is of great importance to ensure food security. Herein, a cyano and ionic dual-functionalized hypercrosslinked porous polymer (CN-iHCP) was designed and prepared for the first time through hyper-crosslink of 1-(4-cyanophenyl)imidazole and 1,4-bis(chloromethyl)benzene. The adsorption mechanism mainly involves electrostatic interaction, hydrogen bonding and π-π stacking interaction. A sensitive analytical method for simultaneous detection of the four phenolic EDCs was established by coupled CN-iHCP based solid-phase extraction with high performance liquid chromatography. Under optimal conditions, the target EDCs exhibited good linearity with coefficient r > 0.993 and high enrichment factors of 164-243. The detection limits (S/N = 3) of EDCs were 0.20-0.50 ng mL-1 for milk sample. The extraction recoveries for the spiked milk samples were in the range of 85.5%- 116.0%. This work not only highlights the CN-iHCP as a promising adsorbent to efficiently enrich EDCs and other pollutants, but also provides a new strategy for the functionalization of HCP for wide applications.

4-Azido-7-nitrobenzoxadiazole as innovative clickable fluorescence probe for trace and selective quantification of ethinylestradiol in human plasma

Quantification of ethinylestradiol (EE) in biological matrices is challenging as it is a very potent drug with a very low Cmax (75 pg.ml-1 ). Despite the high sensitivity of fluorometric methods, the detection of EE was confined because its structure exhibited very limited fluorescence. Therefore, it must be derivatized first using a fluorogenic agent to produce a more potent fluorescence derivative to achieve the desired ultrasensitive bioanalysis. Here, for the first time, we proposed a promising click fluorescent probe, 4-azido-7-nitrobenzoxadiazole (NBD-AZ) to react with the alkyne group of EE, with the help of copper sulphate and l-ascorbic acid to give a highly fluorescent and stable 1,2,3-triazole derivative. Density functional theory calculation revealed how the triazole formation affects the quantum yield and fluorescence of click reaction product when compared with NBD-AZ. The resulting triazole exhibited a strong signal at a wavelength of 540 nm after excitation at 470 nm. Reaction parameters impacting the intensity of fluorescence were cautiously studied and optimized. The suggested approach has shown outstanding performance, high linearity (25-300 pg.ml-1 ) and a low detection limit of 7.5 pg.ml-1 . The enhanced sensitivity and selectivity were exploited for analyzing EE in plasma using liquid-liquid extraction for samples cleaning up without interference from any biological components and with a mean % recovery of 100.13 ± 0.39. Accuracy, sensitivity, selectivity, simplicity, and cost-effectiveness make this approach a convincing, promising, and appealing alternative to the reported analytical methods for EE bioanalysis in different matrices.

Recent advances and applications of magnetic covalent organic frameworks in food analysis

Recently, covalent organic frameworks (COFs) have been widely used to prepare magnetic adsorbents for food analysis due to their highly tunable porosity, large specific surface area, excellent chemical and thermal stability and large delocalised π-electron system. This review summarises the main types and preparation methods of magnetic COFs and their applications in food analysis for the detection of pesticide residues, veterinary drugs, endocrine-disrupting phenols and estrogens, plasticisers and other food contaminants. Furthermore, challenges and future outlook in the development of magnetic COFs for food analysis are discussed.

High Performance Liquid Chromatography (HPLC) with Fluorescence Detection for Quantification of Steroids in Clinical, Pharmaceutical, and Environmental Samples: A Review

Steroids are compounds widely available in nature and synthesized for therapeutic and medical purposes. Although several analytical techniques are available for the quantification of steroids, their analysis is challenging due to their low levels and complex matrices of the samples. The efficiency and quick separation of the HPLC combined with the sensitivity, selectivity, simplicity, and cost-efficiency of fluorescence, make HPLC coupled to fluorescence detection (HPLC-FLD) an ideal tool for routine measurement and detection of steroids. In this review, we covered HPLC-FLD methods reported in the literature for the steroids quantification in clinical, pharmaceutical, and environmental applications, focusing on the various approaches of fluorescent derivatization. The aspects related to analytical methodology including sample preparation, derivatization reagents, and chromatographic conditions will be discussed.

Construction of Binuclear Benzimidazole-Fused Quinazolinones and Pyrimidinones Using Aryl Isocyanates as Building Blocks by Transition-Metal-Free C(sp2)-N Coupling

A class of binuclear N-fused hybrid scaffolds was constructed by the reaction of 2-(2-bromoaryl)- and 2-(2-bromovinyl)benzimidazoles with aryl isocyanates as building blocks in the presence of a base under microwave irradiation. A nucleophilic addition followed by an unprecedented transition-metal-free C(sp²)-N coupling is proposed as a reaction pathway of this green process.