Self-synthesized TiO2 nanoparticles-pH-mediated dispersive solid phase extraction coupled with high performance liquid chromatography for the determination of quinolones in biological matrices

Slice-layer COFs-aerogel: a regenerative dispersive solid-phase extraction adsorbent for determination of ultra-trace quinolone antibiotics

A novel type of three-dimensional network structure, covalent organic frameworks (COFs) aerogel, was fabricated and applied to dispersive solid-phase extraction (dSPE) of quinolone antibiotics (QAs). Density functional theory (DFT) was applied to investigate the possible interaction mechanism and results confirmed that the strong adsorption affinity is attributed to the intralayer hydrogen bonds and π-π interaction. Furthermore, a sensitive analytical method based on COFs-aerogel for determining quinolone antibiotics residues in water and honey samples was developed and HPLC-MS/MS was used for sample detection and quantification. Under the optimal conditions, COFs-aerogel exhibited a wide linearity (0.1-500 ng∙L-1), low limits of detection (0.02-0.06 ng∙L-1), and good precision (RSD ˂ 10%) for selected QAs. A preliminary practical application of the developed method was proved by the efficient detection of quinolone antibiotics in water and food samples with good recoveries (68.2-104% and 64.0-100% for water and honey samples, respectively). Combining the experimental data with theoretical calculation, results illustrated that COFs-aerogel holds a great potential to capture contaminants and address environmental and food safety issues.

Coconut shell biochar application in liquid-solid microextraction of triazine herbicides from multi-media environmental samples

A rapid, fast, widely applicable liquid-solid microextraction and purification method of triazine herbicides (TRZHs) in muti-media samples using salting-out assisted liquid-liquid extraction (SALLE) combined with self-assembled monolithic spin columns-solid phase micro extraction (MSC-SPME) was developed. Environmentally friendly coconut shell biochar (CSB) was used as the adsorbents of MSC-SPME. Ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was the separation and determination method. The adsorption kinetics and isotherms were investigated to indicate the interaction between CSB and TRZHs. Several parameters influencing the liquid-solid microextraction efficiency, such as sample pH, salting-out solution volume and pH, sample loading speed, elution speed, elution ratio and volume of eluent were systematically investigated with the aid of orthogonal design. The whole extraction process was operated within 10 min. Under the optimum extraction and determination conditions, good linearities for three TRZHs were obtained in a range of 0.10-200.00 ng mL^-1, with linear coefficients (R²) greater than 0.999. The limits of detection (LODs) and limits of quantification (LOQs) were in the range of 6.99-11.00 ng L^-1 and 23.33-36.68 ng L^-1, respectively. The recoveries of the three TRZHs in multi-media environmental samples were ranged from 69.00% to 124.72%, with relative standard deviations (RSDs) lower than 0.43%. This SALLE-MSC-SPME-UPLC-MS/MS method was successfully applied to the determination of TRZHs in environmental and food samples and exhibited the advantages of high efficiency and sensitivity, low cost, and environmental friendliness. Compared with the methods published before, CSB-MSC was green, rapid, easy-operated, and reduced the whole cost of the experiment; SALLE combined MSC-SPME eliminated the matrix references effectively; what's more, the SALLE-MSC-SPME-UPLC-MS/MS method could be applied to various sample without complicated sample pretreatment procedure.