Solvent bar microextraction using a reverse micelle containing extraction phase for the determination of warfarin from human plasma by high-performance liquid chromatography

The nonanol/surfactant directed self-assembly supramoleculars heat-shrinkable tubing liquid phase microextraction for determination of flavonoids in natural products combined with high performance liquid chromatography

In this paper, a supramolecular heat-shrinkable tubing liquid phase microextraction was developed for the enrichment and determination of flavonoids. The nonanol adsorbed by the heat-shrinkable tubing could induce the surfactant in aqueous solution to self-assembly on its surface, and formed nonanol/CTAB supramolecules in a directional arrangement. The supramolecules structure enhanced the enrichment efficiency of five flavonoids. The parameters affecting the extraction efficiency were optimized, such as the type of organic solvent, concentration of surfactant, pH and volume of sample phase, salt concentration of sample solution, stirring speed and extraction time. The methodological investigation was carried out under the optimal experimental conditions. The enrichment factors of the five analytes were between 72.3 and 93.3. The concentrations of the target analytes showed good linearity between 0.2 and 5 µg/mL, 0.01-1 µg/mL, 0.01-5 µg/mL, respectively. The limit of detection was no more than 25 ng/mL. The procedure was successfully applied in extraction of five flavonoids from the natural products according to its average recoveries of 98.3-101.7 %.

Magnetic solid-phase extraction of warfarin and gemfibrozil in biological samples using polydopamine-coated magnetic nanoparticles via core-shell nanostructure

Herein, polydopamine-coated Fe₃ O₄ spheres were synthesized using a very simple, easy, cost-effective, efficient, and fast method. First, magnetic nanoparticles (Fe₃ O₄ ) were synthesized and were followed by accommodating polydopamine on the surface of the prepared Fe₃ O₄ . The prepared polydopamine-coated Fe₃ O₄ spheres were utilized as a sorbent in magnetic solid phase extraction of gemfibrozil and warfarin (as the model analytes). The extracted model analytes were desorbed by a suitable organic solvent and were analyzed by high-performance liquid chromatography. Under optimized condition, the linearity of the method was in the range of 0.1-200.0 μg/L for the selected analytes in water. The limits of detection were calculated to be in the range of 0.026-0.055 μg/L for warfarin and gemfibrozil, respectively. The limits of quantification were calculated to be in the range of 0.089-0.185 μg/L. The inter-day and intra-day relative standard deviations were determined to be in the range of 1.4%-3.3% in three concentrations in order to calculate the method precision. Furthermore, the enrichment factors were found to be 78 and 81 for warfarin and gemfibrozil, respectively. Moreover, the calculated absolute recoveries were between 78% and 81%. The obtained recoveries indicated that the method was useful and applicable in complicated real samples.

Hydrophobic microporous extraction on polyurethane sponges for convenient and sensitive analysis of organic molecules in water

RATIONALE

Various solvent supports have been developed to overcome solvent instability during liquid-phase microextraction. The hydrophobic polyurethane sponge (PS) possesses numerous cross-linked internal microchannels and terminal micropores that can facilitate steady solvent storage capacity, high extraction efficiency, extractant loading, and recycling convenience.

METHODS

In this study, an easy, convenient, and efficient PS-supported liquid-phase microextraction (PS-LPME) coupled with gas chromatography-mass spectrometry (GC-MS) method was developed for the trace analysis of different organic compounds in aqueous solutions. Different extraction solvents, PS dosages, stirring speeds, and extraction times were first investigated by extracting eight polycyclic aromatic hydrocarbons (PAHs: naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene), and then applied for the analysis of triazines, amides, chloroacetamides, and organophosphorus compounds.

RESULTS

High enrichment factors (approximately 208-439) were observed for the monitored PAHs. Good linearities, with determination coefficients (r² ) greater than 0.9992, were achieved in the concentration range of 0.01-50 μg L^-1 . Low limits of detection and quantification were found in the ranges of 0.3-3 ng L^-1 and 1-10 ng L^-1 , respectively. At three spiked concentrations (0.1, 1, and 10 μg L^-1 ), good recoveries were obtained in the range of 91.6-118.5% with intra- and inter-day relative standard deviations of less than 6.4% and 11.7%, respectively.

CONCLUSIONS

The developed PS-LPME method coupled with GC-MS was successfully applied in the analysis of different organic compounds in aqueous solutions and has shown great convenience and satisfactory enrichment performance in microextraction analysis.

Nanofluid of magnetic-activated charcoal and hydrophobic deep eutectic solvent: Application in dispersive magnetic solid-phase extraction for the determination and preconcentration of warfarin in biological samples by high-performance liquid chromatography

In this study, for the first time, nanofluid of magnetic-activated charcoal and hydrophobic deep eutectic solvent (AC@Fe₃ O₄ -DES) based dispersive magnetic solid-phase extraction was successfully applied for the determination and preconcentration of warfarin in plasma and urine samples. The hydrophobic DES was prepared by mixing tetramethylammonium chloride (as hydrogen bond acceptor) and thymol (as hydrogen bond donor) and acted simultaneously as both carrier and stabilizer for magnetic nanoparticles. In this method, the nanofluid as a new extraction solvent was rapidly injected into the aqueous sample, which led to improvement of the mass transfer of the analytes into the sorbent and reduction of the extraction time. In the screening step, the fractional factorial design was applied for selecting some important parameters which significantly affected the extraction procedure. The effective parameters were then optimized by Box-Behnken design. Under the optimal conditions, the limits of detection were in the range of 0.3-1.6 ng/ml. A good linear range was observed in the range of 1.0-500.0 ng/ml for water and 5.0-500.0 ng/ml for urine and plasma. The intra- and inter-day relative standard deviations were 2.7-3.2 and 1.9-4.5% for five replications, respectively. Based on the results, the proposed method was successfully applied for the determination of warfarin in biological samples, using high-performance liquid chromatography.

Recent applications of microextraction sample preparation techniques in biological samples analysis

Analysis of biological samples is affected by interfering substances with chemical properties similar to those of the target analytes, such as drugs. Biological samples such as whole blood, plasma, serum, urine and saliva must be properly processed for separation, purification, enrichment and chemical modification to meet the requirements of the analytical instruments. This causes the sample preparation stage to be of undeniable importance in the analysis of such samples through methods such as microextraction techniques. The scope of this review will cover a comprehensive summary of available literature data on microextraction techniques playing a key role for analytical purposes, methods of their implementation in common biological samples, and finally, the most recent examples of application of microextraction techniques in preconcentration of analytes from urine, blood and saliva samples. The objectives and merits of each microextration technique are carefully described in detail with respect to the nature of the biological samples. This review presents the most recent and innovative work published on microextraction application in common biological samples, mostly focused on original studies reported from 2017 to date. The main sections of this review comprise an introduction to the microextraction techniques supported by recent application studies involving quantitative and qualitative results and summaries of the most significant, recently published applications of microextracion methods in biological samples. This article considers recent applications of several microextraction techniques in the field of sample preparation for biological samples including urine, blood and saliva, with consideration for extraction techniques, sample preparation and instrumental detection systems.

Solvent bar microextraction combined with HPLC-DAD for simultaneous determination of diuretics in human urine and plasma samples

BACKGROUND

A simple and powerful microextraction procedure, the solvent bar microextraction (SBME), was used for the simultaneous determination of two diuretics, furosemide and spironolactone in human urine and plasma samples, using high-performance liquid chromatography coupled with diode array detection (HPLC-DAD).

METHODS

The appropriate amount (2 µL) of 1-octanol as an organic solvent confined within (2.5 cm) of a porous hollow fiber micro-tube, sealed at both ends was used for this procedure. The conditions for the SBME were optimized in water and the analytical performance were examined in spiked human urine and plasma samples.

RESULTS

The optimized method exhibited good linearity (R2 > 0.997) over the studied range of higher than 33 to 104 µg L-1 for furosemide and spironolactone in urine and plasma samples, illustrating a satisfactory precision level with RSD values between 2.1% and 9.1%.

DISCUSSION

The values of the limits of detection were found to be in the range of 6.39 to 9.67 µg L-1, and extraction recovery˃ 58.8% for both diuretics in urine and plasma samples. The applicability and effectiveness of the proposed method for the determination of furosemide and spironolactone in patient urine samples were tested.

CONCLUSION

In comparison with reference methods, the attained results demonstrated that SBME combined with HPLC-DAD was proved to be simple, inexpensive, and promising analytical technology for the simultaneous determination of furosemide and spironolactone in urine and plasma samples.

Simultaneous extraction and analysis of clozapine and lorazepam from human plasma using dual solvent-stir bar microextraction with different acceptor phases followed by high-performance liquid chromatography ultra-violet detection

A new design of dual solvent stir bar microextraction (DSSBME) was developed and combined with HPLC-UV for the simultaneous extraction of clozapine (CLZ) and lorazepam (LRP) from human plasma with different acceptor phases. Two short hollow fibers immobilized with an organic extraction solvent were used as the solvent bars for microextraction of CLZ and LRP from the sample solution. The solvent bars were fixed with a staple pin which served as the stirrer. The target analytes were simultaneously and selectively extracted from the sample solution into their corresponding solvent bar. Extraction parameters such as organic solvent type, pH of the sample solution, the acceptor phase concentration, salt incorporation into the solution, stirring rate, and extraction time were optimized to achieve the best extraction results. Under the optimum conditions (1-undecanol as extraction solvent, pH of sample solution = 9.0, 10% w/v NaCl, concentration of HCl = 10 mM, concentration of NaOH = 100 mM, stirring rate of 1400 rpm and extraction time of 30 min at ambient temperature) the limit of detection for CLZ was 0.4 ng mL^-1 and for LRP it was 1.1 ng mL^-1. The linear range for CLZ was 1.3-1000.0 ng mL^-1 (R² = 0.9991) and for LRP it was 3.6-800.0 ng mL^-1 (R² = 0.9993). Extraction recovery and the enrichment factor for CLZ were 95.4% and 343 and for LRP they were 74.3% and 263, respectively. Finally, the method developed was successfully applied for the simultaneous determination of CLZ and LRP in human plasma samples.

Hydrophobic borneol-based natural deep eutectic solvents as a green extraction media for air-assisted liquid-liquid micro-extraction of warfarin in biological samples

In the present study, a new generation of water-immiscible natural deep eutectic solvents (DESs) was synthesized using borneol as a hydrogen-bonding acceptor and decanoic acid, oleic acid, and thymol as a hydrogen-bonding donor in different molar ratios. These green hydrophobic solvents which are chemically stable in aqueous solutions were used as extraction solvents for isolation and pre-concentration of warfarin in biological samples. In this method, fine droplets of DESs were dispersed into the sample solution by using the air-assisted liquid-liquid micro-extraction method to accelerate the cloudy emulsion system formation and increase the mass transfer of the analyte to the DES-rich phase. The borneol based deep eutectic solvent is a worthy generation of the extraction solvents in the ALLME method due to low-cost and less toxicity. A Plackett-Burman design was utilized for screening the experimental parameters. The effective parameters were then optimized by Box-Behnken design (BBD). Optimized extraction conditions were pH of sample solution of 3.9, number of aspiration/dispersion cycles of 15, the volume of DES of 60 μL, and rate and time of centrifuge of 6000 rpm and 10 min, respectively. Under the optimized conditions, the developed NADES-ALLME method exhibited a wide linear range of 5-500 µg L ^- 1 for plasma and urine samples with satisfactory recoveries above 88.80%. Limit of detections (LODs) and Limit of quantifications (LOQs) of warfarin were in the ranges of 0.5-2.7 and 1.65-8.91, respectively. The enrichment factors were obtained in the range of 148-164 and precisions were lower than 5.87%. Finally, the proposed method was successfully employed for the analysis of warfarin in human urine and plasma samples.

Progress in Pretreatment and Analytical Methods of Coumarins: An Update since 2012 - A Review

Coumarins are widely used due to their wide range of biological activities, but the long-term or excessive use of coumarin flavors can pose serious health hazards. Therefore, sensitive and specific methods for the quantification of these compounds in different matrices have been developed. In this review, an updated overview of the latest trends in sample preparation techniques and methods used to detect coumarins from March 2012 to April 2019 is provided. This study reviews different analytical methods (such as liquid chromatography coupled with different detectors, electrochemical sensors, capillary electrophoresis, etc.) and different pretreatment methods (such as liquid-liquid extraction, solid-phase extraction, dispersive liquid-liquid microextraction, etc.). Different methods for the pretreatment and determination of coumarins in plant, food, environmental, pharmaceutical and biological samples are summarized, discussed and compared.HighlightsProgress in pretreatment and analytical methods of coumarins are summarized.Fundamentals, instrumentation and applications of purification and quantification are summarized and compared.Optimization of experimental conditions are discussed.Newly emerged eco-friendly methods are introduced.