Thin film microextraction of apixaban from plasma based on the covalent organic framework coated on a mesh prior to liquid chromatography-tandem mass spectrometry.

In this research, a new covalent organic framework was synthesized and utilized as a coating in thin film microextraction for the extraction of apixaban from plasma samples. This coating was applied to the mesh modified through immersion in a HF solution. The extracted drug was then analyzed using liquid chromatography-tandem mass spectrometry. By combining the high specific surface area and selectivity of the covalent organic framework, along with integrating the innovative thin film microextraction method and a sensitive analysis system, an efficient analytical approach was achieved. The target analyte was preconcentrated and extracted by immersing of the covalent organic framework-coated mesh as an absorbent into the biological sample. Subsequently, a sonication process was conducted for a specific duration. Following this, the extracted analyte was desorbed using acetonitrile as the elution solvent. The effective parameters of the proposed technique were optimized by using "one-parameter-at-a-time" strategy and the optimal conditions were selected. By integrating the developed method notable achievements were made in the terms of low limits of detection and quantification (0.17 and 0.56 µg/L, respectively), a wide linear range (0.05-250 µg/L), intra- and inter day precisions (with relative standard deviations of ≤14 %), as well as satisfactory extraction recoveries (53 % and 54 % in plasma and deionized water, respectively). Hence, it can be concluded that the introduced technique exhibits high efficiency and reliability when applied to biological samples.

Heteroatom cobalt-based metal-organic framework and reduced graphene oxide nanocomposite for dispersive solid phase extraction of caffeine from exhaled breath condensate samples of premature infants prior to HPLC-PDA.

A cobalt-based metal-organic framework and graphene oxide were combined to prepare a new nanocomposite for extracting of caffeine from exhaled breath condensate (EBC) samples. Dispersive micro solid phase extraction of caffeine was conducted using the nanocomposite as a sorbent by adding 10 mg of it to the sample solution and vortexing for 3 min. After extracting of the analyte, it was eluted using the mobile phase. The analyte was then analyzed using high performance liquid chromatography-photodiode array detector. Under optimal conditions, the limit of detection, limit of quantification, and linear range of the calibration curve were found to be 1.7, 5.9, and 10-500 µg/L, respectively. To assess the precision of the method, five replicates of standard solutions containing caffeine at two different concentration levels (50 and 100 µg/L) were tested. The relative standard deviations for intra- and inter-day precisions ranged from 4.3 to 6.8 %. The applicability of the method was demonstrated by analyzing the samples obtained from premature infants undergoing caffeine treatment and caffeine concentrations were 4.9 ± 0.6, 2.7 ± 0.2 µg/L in the EBC samples of who were under treatment by a 5-mg dose. Also, caffeine concentrations were 5.9 ± 0.3 and 18 ± 0.6 µg/L in the the infants who obtained the 10-mg and 25-mg doses, respectively. The results indicated a satisfactory, extraction recovery of 86 % showcasing the method's reliability and effectiveness in analyzing real samples.

Development of a hollow fiber-liquid phase microextraction method using tissue culture oil for the extraction of free metoprolol from plasma samples.

In this research, a method known as a hollow fiber-liquid-phase microextraction was employed to extract and concentrate free metoprolol from plasma samples. The extracted analyte was subsequently determined using high-performance liquid chromatography coupled with a diode-array detector. Several parameters, including hollow fiber length, sonication time, extraction temperature, and salt addition, were investigated and optimized to enhance extraction efficiency. After extracting the analyte under optimum conditions from plasma samples, the enrichment factor and extraction recovery were 50 and 86 %, respectively. Moreover, the method exhibited detection and quantification limits of 0.41 and 1.30 ng mL-1, respectively. The analysis of real samples demonstrated satisfactory relative recoveries in the range of 91-99 %.

Application of magnetic dispersive solid phase extraction combined with solidification of floating organic droplet-based dispersive liquid-liquid microextraction and GC-MS in the extraction and determination of polycyclic aromatic hydrocarbons in honey.

A magnetic dispersive solid phase extraction method combined with solidification of floating organic droplet-based dispersive liquid-liquid microextraction has been validated for the extraction of polycyclic aromatic hydrocarbons from honey samples. For this purpose, a carbonised cellulose-ferromagnetic nanocomposite was used as a sorbent through the magnetic dispersive solid phase extraction. For preparation of the sorbent, first, carbonised cellulose nanoparticles were created by treating cellulose filter paper with concentrated solution of sulfuric acid. Then, the prepared nanoparticles were loaded onto Fe3O4 nanoparticles through coprecipitation. In the extraction process, first, a few mg of the sorbent was added to the diluted honey solution and dispersed in it using vortex agitation. The particles were then separated and the adsorbed analytes were eluted with an organic solvent. The eluent was taken and after mixing with a water-immiscible extraction solvent was used in the following solidification of floating organic droplet-based dispersive liquid-liquid microextraction procedure. By performing the extraction process under the obtained optimum conditions, low limits of detection (0.08-0.17 ng g-1) and quantification (0.27-0.57 ng g-1), satisfactory precision (relative standard deviations ≤ 5.0%), and wide linear range (0.57-500 ng g-1) with great coefficients of determination (r2≥ 0.9986) were obtained.

Dispersive solid phase extraction of tacrolimus from biological samples using curcumin and iron-based metal organic frameworks nanocomposite followed by LC-MS/MS determination.

Tacrolimus is a potent immunosuppressive drug used in the prevention of tissue rejection. It has a narrow therapeutic index. Therefore, the determination of its concentration in biological fluids like plasma and urine is a very crucial issue. In this research, tacrolimus concentrations in plasma and urine samples were determined with a dispersive solid phase extraction procedure coupled to high-performance liquid chromatography-tandem mass spectrometry. For this purpose, a curcumin modified metal-organic framework was synthesized and used in extraction procedure. Tacrolimus was adsorbed onto the sorbent surface with aid of vortexing. Then, the adsorbed tacrolimus was eluted by a suitable solvent. Important parameters in extraction procedure were optimized by "one-variable-at-a-time" approach and reported as below: sorbent amount, 10 mg; sample solution pH, 2; agitation mode, vortexing; adsorption and desorption times, 1 min, and eluent (volume), methanol (200 µL). Under the optimized conditions and according to the International Council for Harmonization guidelines, the validation of the method was performed, and the results showed acceptable accuracy and precision (relative standard deviations ≤14 %), good linearity in a wide range (4-200 ng mL-1), and low limits of detection (1.2 ng mL-1 in plasma and 0.34 ng mL-1 in urine) and quantification (4.7 ng mL-1 in plasma and 1.12 ng mL-1 in urine). Finally, the validated method was successfully applied for the determination of tacrolimus in the plasma samples of the patients.

Determination of copper(II) and lead(II) ions in dairy products by an efficient and green method of heat-induced homogeneous liquid-liquid microextraction based on a deep eutectic solvent.

In this study, a new homogeneous liquid-liquid microextraction method using a deep eutectic solvent has been developed for the extraction of Cu(II) and Pb(II) ions in dairy products. Initially, the deep eutectic solvent was synthesized using choline chloride and p-chlorophenol and used as the extraction solvent. The synthesized solvent was soluble in milk at 70 °C and its separation from the sample was performed by decreasing the temperature. By cooling, a cloudy solution was formed due to the low solubility of the solvent at low temperatures. On centrifugation, the fine droplets of the solvent containing the analytes settled at the bottom of the tube by sedimentation. The enriched analytes were determined by flame atomic absorption spectrometry. The effect of some important parameters such as the amount of protein precipitating agent , complexing agent amount, extraction solvent volume, salt addition, pH, and temperature on the extraction efficiency of the method was studied and optimized. Under the optimal conditions, the linear ranges of the method for Cu(II) and Pb(II) ions were obtained in the ranges of 0.10-50 and 0.50-50 µg L-1 with detection limits of 0.04 and 0.18 µg L-1, respectively. The repeatability of the developed method, expressed as relative standard deviation, was determined to be 3.2 and 3.9% for Cu(II) and Pb(II) ions, respectively. Finally, by determining the concentration of Cu(II) and Pb(II) ions in milk, doogh, and cheese samples, the feasibility of the method was successfully confirmed with the extraction recoveries of 95.9 and 92.1% for Cu(II) and Pb(II) ions, respectively.

Selective extraction of apixaban from plasma by dispersive solid-phase microextraction using magnetic metal organic framework combined with molecularly imprinted polymer nanocomposite.

This research aims to synthesize a specific and efficient sorbent to use in the extraction of apixaban from human plasma samples and its determination by high-performance liquid chromatography-tandem mass spectrometry. High specific surface area of metal-organic framework, magnetic property of iron oxide nanoparticles, selectively of molecular imprinted polymer toward the analyte, and the combination of dispersive solid-phase extraction method with a sensitive analysis system provided an efficient analytical method. In this study, first, a molecularly imprinted polymer combined with magnetic metal organic framework nanocomposite was prepared and then characterized using different techniques. Then the sorbent particles were used for selective extraction of the analyte from plasma samples. The efficiency of the method was improved by optimizing effective parameters. According to the validation results, wide linear range (1.02-200 ng mL-1 ), acceptable coefficient of determination (0.9938), low limit of detection (0.32 ng mL-1 ) and limit of quantification (1.02 ng mL-1 ), high extraction recovery (78%), and good precision (relative standard deviations ≤ 2.9% for intra- (n = 6) and interday (n = 6) precisions) were obtainable using the proposed method. These outcomes showed the high potential of the proposed method for screening apixaban in the human plasma samples.