Low-density solvent-based dispersive liquid–liquid microextraction followed by high performance liquid chromatography for determination of warfarin in human plasma

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.

Corona discharge ionization ion mobility spectrometry for ultra-trace determination of methamphetamine extracted from urine and plasma samples by dispersive liquid-liquid microextraction

In this work, dispersive liquid-liquid microextraction (DLLME) based on high-density extraction solvent was applied as a simple, fast and sensitive method for extraction and preconcentration of methamphetamine from human plasma and urine samples. The efficiency of positive corona discharge ionization ion mobility spectrometry was investigated for direct analysis of the extracted analyte. Effective parameters on the extraction efficiency, such as type and volume of the extraction and disperser solvents, centrifugation time, and sample solution pH were optimized. Trichloromethane and isopropanol were selected as the extracting and disperser solvents, respectively. Under the optimized conditions, the linear dynamic range (R² = 0.9969) was found to be 0.5-18 µg/L, and 0.15 µg/L was calculated as the limit of detection. The relative standard deviations of intra- and inter-day were obtained 4 and 10%, respectively, and finally, in the analysis of human plasma and urine samples, the extraction recovery was obtained 104%.

Warfarin Induced Quenching of the Carbon Quantum Dots: Mechanism Study and Warfarin Sensor Construction

The mechanism of the fluorescence quenching of the CQDs by warfarin was determined and based on this study a simple, low cost and highly sensitive nanosensor was developed for determination of Warfarin in plasma samples. The carbon quantum dots with 3.5 µs lifetime (halflife of 2.4 µs) were synthesized by hydrothermal method and characterized. The fluorescence rate constant of 4.5 × 10⁴ s^-1 and quenching rate constant of 6.18 × 10⁴ s^-1 (from 10 μM warfarin that result in 17% lifetime reduction) was calculated. High quenching efficiency results in 21.63 L mmol^-1 Stern-Volmer constant and the study of pH and temperature also confirm the dynamic quenching mechanism. The second order rate constant of 6.18 × 10⁴ L mmol^-1 s^-1 was obtained for collisions between CQDs and warfarin. Based on this mechanism, a simple, low cost and very sensitive warfarin nanosensor was developed with calibration sensitivity of 21.63 L mmol^-1, working range of 0.10 - 12.00 μM and detection limit of 0.01 μM.

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.

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.

Determination of Levetiracetam in Human Plasma by Dispersive Liquid-Liquid Microextraction Followed by Gas Chromatography-Mass Spectrometry

Levetiracetam (LEV) is an antiepileptic drug that is clinically effective in generalized and partial epilepsy syndromes. The use of this drug has been increasing in clinical practice and intra- or -interindividual variability has been exhibited for special population. For this reason, bioanalytical methods are required for drug monitoring in biological matrices. So this work presents a dispersive liquid-liquid microextraction method followed by gas chromatography-mass spectrometry (DLLME-GC-MS) for LEV quantification in human plasma. However, due to the matrix complexity a previous purification step is required. Unlike other pretreatment techniques presented in the literature, for the first time, a procedure employing ultrafiltration tubes Amicon® (10 kDa porous size) without organic solvent consumption was developed. GC-MS analyses were carried out using a linear temperature program, capillary fused silica column, and helium as the carrier gas. DLLME optimized parameters were type and volume of extraction and dispersing solvents, salt addition, and vortex agitation time. Under chosen parameters (extraction solvent: chloroform, 130 μL; dispersing solvent: isopropyl alcohol, 400 μL; no salt addition and no vortex agitation time), the method was completely validated and all parameters were in agreement with the literature recommendations. LEV was quantified in patient's plasma sample using less than 550 μL of organic solvent.

In-syringe low-density ionic liquid dispersive liquid–liquid microextraction for the fast determination of pyrethroid insecticides in environmental water samples by HPLC-DAD

In-syringe low-density ionic liquid dispersive liquid–liquid microextraction.

Dispersive liquid-liquid microextraction: trends in the analysis of biological samples

Dispersive liquid-liquid microextraction (DLLME) is a recent microextraction technique that was first developed by Rezaee and co-workers in 2006. It allows the simultaneous extraction and preconcentration of analytes into a micro-volume of extracting solvent based on a ternary solvent system involving an aqueous phase, a nonpolar water immiscible high-density solvent that acts as extraction phase, and a disperser solvent, which is often polar and water miscible. This article presents an overview of DLLME applications in the analysis of biological samples (e.g., plasma and urine). Aside from the classical DLLME applications using high density extraction solvents, recent advances in the use of low density solvents and ionic liquids are also discussed. Although most of the applications deal with the analysis of organic target compounds, a few applications on the bioanalysis of inorganic substances are also included.

Recent advances in unique sample preparation techniques for bioanalysis

The extraction and/or purification of drugs and medicines from biological matrices are important objectives in investigating their toxicological and pharmaceutical properties. Many widely used methods such as liquid–liquid extraction or SPE, used for extracting, purifying and enriching drugs and medicines found in biological materials, involve laborious, intensive and expensive preparatory procedures, and they require organic solvents that are toxic to both humans and the environment. Recent trends are focused on miniaturization, high-throughput and automation techniques. All the advantages and disadvantages of these techniques and devices in biological analysis are presented, and their applications in the extraction and/or purification of drugs and medicines from biological matrices are discussed in this review.

Estimation of plasma levels of warfarin and 7-hydroxy warfarin by high performance liquid chromatography in patients receiving warfarin therapy

Warfarin is one of the most commonly prescribed oral anticoagulant for prevention of thromboembolic events. The effect of this drug is measured by monitoring prothrombin time expressed as International Normalized Ratio (INR). In some cases, however, the measurement of plasma concentration of warfarin was emphasized. In the present study, reversed phase high performance liquid chromatography (HPLC) was used to estimate the plasma drug levels. A total of 185 patients were enrolled in this study. Five milliliter of venous blood was collected using sodium EDTA tubes for pharmacokinetic analysis. Solid phase extraction was used to recover the warfarin and it's metabolite from plasma using isopropanol and potassium phosphate buffer (40:60) mobile phase. Warfarin, 7-hydroxy warfarin and carbamazepine (internal standard) were separated on a C18 column and had the retention time 3.6 min, 2.9 min and 5.9 min, respectively. The assay was linear in warfarin concentration ranges of 0.1-5 μg/ml. The extraction recovery was found to be ≃85%. The mean plasma concentrations of warfarin and 7-hydroxy warfarin were found to be 3.47 ± 1.87 (SD) μg/ml, 1.25 ± 0.81 (SD) μg/ml, respectively. Through the present study the plasma concentrations of warfarin, 7-hydroxy warfarin and their metabolic ratio was determined. The assay was sensitive to follow warfarin pharmacokinetics in a patient with warfarin therapy for 3 months and above.

Analysis of losartan and carvedilol in urine and plasma samples using a dispersive liquid–liquid microextraction isocratic HPLC–UV method

Background: A simple, precise and sensitive HPLC method has been developed for simultaneous determination of carvedilol and losartan in human plasma and urine samples. The analytes were extracted by a dispersive liquid–liquid microextraction method. A mobile phase of 15 mM sodium dihydrogen phosphate buffer (pH 4.0)/acetonitrile/2-propanol (70/27.5/2.5, v/v/v) was used to separate the drugs using a Waters® ODS column (250 × 4.6 mm) and detected by a UV detector at 222 nm. Results: The developed method is selective for studied drugs possessing a linearity range of 0.1–1.0 and 0.05–0.75 µg/ml, respectively, for losartan and carvedilol with precision <15%. The accuracy is better than 15% and the mean recovery of carvedilol and losartan was 98.9 and 100.2% for plasma and 100.7 and 100.5% for urine samples, respectively. Conclusion: The developed method is applicable for therapeutic drug monitoring and PK analyses.