Application of hollow fiber membrane mediated with titanium dioxide nanowire/reduced graphene oxide nanocomposite in preconcentration of clotrimazole and tylosin

Synthesis of composite materials combining magnetic metal-organic frameworks and conjugated organic frameworks for selective extraction of carbendazim and thiabendazole residues from Chinese herbal medicine samples

A magnetic metal-organic framework MIL-68(Al) and a covalent organic framework were used as magnetic solid-phase extraction (MSPE) adsorbents in combination with high-performance liquid chromatography ultraviolet detection (HPLC-UV) to detect carbendazim (CBZ) and thiabendazole (TBZ). The main parameters affecting the extraction in the MSPE process were studied and optimized. Fe3O4@MIL-68(Al) coated with 1,3,5-tris(4-aminophenyl)benzene and terephthaldehyde (Fe3O4@MIL-68(Al)@TAPB-PDA-COF) was analyzed and verified. The material was proven to be suitable for adsorbing CBZ and TBZ. Various adsorption models were used to study its adsorption mechanism. The adsorption results were in good agreement with the pseudo-second-order kinetic model and Langmuir isotherm model. The maximum adsorption capacities of Fe3O4@MIL-68(Al)@TAPB-PDA-COF over CBZ and TBZ were 54.24 and 67.87 mg g-1, respectively, and the equilibrium adsorption time was 200 min. Fe3O4@MIL-68(Al)@TAPB-PDA-COF with excellent recyclability showed higher adsorption capacity and selectivity. A method based on Fe3O4@MIL-68(Al)@TAPB-PDA-COF combined with HPLC-UV was established under the optimal extraction conditions and used to separate and detect trace imidazole drugs in Chinese herbal samples, achieving a low limit of detection (0.65-1.30 μg L-1) with excellent linear correlation (r > 0.999). The recovery rate and relative standard deviation were 86.05-99.78 % and 0.15-4.90 %, respectively. Therefore, the Fe3O4@MIL-68@TAPB-PDA-COF can be regarded as an effective adsorbent for the pretreatment of CBZ and TBZ drugs in Chinese herbal samples.

Air assisted in situ deep eutectic solvent decomposition followed by the solidification of floating organic droplets-liquid-liquid microextraction method for extraction of azole antifungal drugs in biological samples prior to high-performance liquid chromatography

A free dispersive method, air-assisted in situ deep eutectic solvent decomposition followed by the solidification of floating organic droplets liquid-liquid microextraction was indicated in this study. This technique was utilized to simultaneously ascertain some azole antifungal drugs prior to high-performance liquid chromatography. In this research, a quasi-hydrophobic deep eutectic solvent was formed from tetrabutylammonium bromide and 1-dodecanol as an organic solvent at a 1:2 molar ratio. The synthesized deep decomposition in the sample solution caused in situ dispersion of extraction solvent and analytes. Air-assisted enhanced a dispersion condition in the sample solution. 1-dodecanol as a green option was replaced with typical extraction solvents providing the advantages of a suitable freezing point near room temperature and low density. The effect of important analytical parameters on the extraction recovery of analytes was assessed. Under these optimal conditions, the limits of detection and limits of quantitation determined were in the range of 0.5-2.8 μg L^-1 and 1.5-9 μg L^-1 , for water, urine and plasma samples, respectively. The Intra-day and inter-day relative standard deviations (RSD% n = 5) were calculated to be 2.9-4.6 % and 4.2-8.9 %, respectively. The results represented the effectiveness of the developed method for the extraction and determination of analytes in biological samples. This article is protected by copyright. All rights reserved.

FTIR spectroscopy with chemometrics for determination of tylosin residues in milk

BACKGROUND

Contamination of milk by antibiotic residues represents risks to the health of consumers; therefore they should be monitored. The objective of this study was to propose a methodology for the determination of tylosin residues directly in fluid milk based on mid-infrared spectroscopy associated with chemometrics, using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy associated with multilayer perceptron network (MLP) and partial least squares (PLS).

RESULTS

MLP was shown to be adequate for the discrimination of milk samples contaminated with tylosin below or equal to or above the maximum residue limit (MRL), with an accuracy greater than 99%, using FTIR spectra data. PLS was shown to be appropriate for the prediction of the very low concentrations (0-100 μg L^-1 ) of tylosin residues in milk using FTIR spectra data. PLS models with high correlation coefficients (R > 0.99) were generated.

CONCLUSION

FTIR with chemometrics proved to be a non-destructive, efficient and low-cost method for the investigation and quantification of tylosin residues directly in fluid milk. © 2020 Society of Chemical Industry.

Investigation of adsorption performance of graphene oxide/polyaniline reinforced hollow fiber membrane for preconcentration of Ivermectin in some environmental samples

Herein, the application of Graphene oxide-polyaniline (GO/PANI) in one of newly hollow fiber based microextraction techniques so called (HF-S/LPME) was investigated successfully. Graphene oxide-polyaniline (GO/PANI) nanocomposite was generated via an amidation reaction in the presence of N, N'-dicyclohexylcarbodiimide (DCC), N-hydroxysuccinimide (NHS) and GO as starting material. The solid sorbent dispersed in dihexyl ether was immersed and injected into the lumen of hollow fiber. The results indicated that GO/PANI had a higher adsorption efficiency for the Ivermectin in comparison with GO and GO-ethylen diamine (GO/EDA). A Taguchi experimental design with an OAD₁₆ (4⁵) matrix was employed to optimize the affecting parameters such as pH, stirring rate, extraction time, salt addition and the volume of donor phase. Under the optimized extraction conditions, the method showed a good linear dynamic range (0.1-5000.0 ppb) with a lower limit of detection (0.03 ppb) and excellent preconcentration factor (PF = 219.88) respectively.

Ultrasound-assisted extraction of bioactive compounds from Malva sylvestris leaves and its comparison with agitated bed extraction technique

The effects of ultrasound-assisted extraction (UAE) variables-namely extraction temperature (40-60 °C), ultrasonic power (50-150 W), and sonication time (40-60 min)-on the extractive value (EV) of bioactive phenolics from Malva sylvestris leaves were investigated and optimized using Response surface methodology. The effects of extraction solvents (ethanol, ethyl acetate, and n-hexane) on EV, free radical scavenging activity (FRSA), total phenolic content (TPC), and major bioactive phenolics were studied using agitated bed extraction (ABE), and the results were compared with the UAE findings. Under the optimal UAE conditions (48 °C, 110.00 W, and 48.77 min) the experimental EV was 279.89 ± 0.21 mg/g with 71.12 ± 0.15% DPPH_sc, 73.35 ± 0.11% ABTS_sc, and a TPC of 152.25 ± 0.14 mg GAE/g. Ethanolic ABE results in higher EV (320.16 ± 0.25 mg g^-1) compared to UAE, while the FRSA and TPC values were reduced. HPLC analysis revealed that the concentration of bioactive phenolics increased significantly (p < 0.05) under the optimal UAE conditions.

Application of nanocomposite-based sorbents in microextraction techniques: a review

This review provides a general overview of the recent trends for the preparation of nanocomposites and their applications in microextraction techniques.