Application of modified stir bar with nickel:zinc sulphide nanoparticles loaded on activated carbon as a sorbent for preconcentration of losartan and valsartan and their determination by high performance liquid chromatography

Synthesis of molecularly imprinted polymer as a nanosorbent for dispersive magnetic micro solid-phase extraction and determination of valsartan in biological samples by UV-Vis Spectrophotometry: Isotherm, kinetics, and thermodynamic studies

A magnetic molecularly imprinted polymer (MIP) was synthesized by precipitation polymerization utilizing Fe₃O₄@SiO₂-MPS as a magnetic core, itaconic acid as a functional monomer, azobisisobutyronitrile as an initiator, and ethylene glycol dimethacrylate as a cross linker. It was then applied as a nanosorbent for dispersive magnetic micro solid phase extraction (DM-µ-SPE) and determination of valsartan in biological fluids. The morphology and structure of magnetic MIP were characterized by Fourier-transform infrared spectroscopy, Field Emission Scanning electron microscopy, Vibrating sample magnetometer, Energy dispersive x-ray analysis, and Thermogravimetric analysis. The influence of operation conditions on sorption, such as pH (4-10), contact time (10-25 min), initial concentration (1-30 mg L^-1), and temperature (25-40 °C) was investigated. After the extraction step, the valsartan concentration was determined by UV-Vis spectrophotometer at 253 nm. The isotherm and kinetic of valsartan sorption were best fitted by the Langmuir model (R² = 0.987) and the Pseudo second-order kinetic model (R² = 0.971), respectively. The maximum monolayer sorption capacity for magnetic MIP was obtained to be 4.56 mg g^-1. The analytical approach demonstrated favorable figures of merit, with a linear dynamic range of 10-100 µg L^-1, a low detection limit of 0.56 µg L^-1, and an acceptable preconcentration factor of 5 acquired in optimum conditions. The recoveries of the suggested technique at three spiked levels of analysis were in the range of 101 %-102 %. Valsartan was extracted from various real samples (urine and human blood plasma samples) utilizing the proposed magnetic nanosorbent, and the results exhibited that magnetic MIP was favorable for extraction and measurement of trace amounts of valsartan in biological samples.

A Rapid Analytical Approach for Monitoring Pharmaceuticals in Hospital Wastewater—A DPX-Based Procedure with Environmentally-Friendly Extraction Phase Coupled to High Performance Liquid Chromatography–Diode Array/Fluorescence Detectors

In this study, a novel analytical methodology based on disposable pipette extraction (DPX) was developed using an alternative extraction phase for the extraction/determination of six pharmaceutical compounds, including carbamazepine, diclofenac, naproxen, fluoxetine, losartan and 17α-ethinylestradiol, in samples of hospital wastewater by high-performance liquid chromatography coupled to diode array and fluorescence detectors. The performance of three extraction phases was examined, including 3-n-propyl (3-methylpyridinium) silsesquioxane chloride (Si3Py+Cl−), the conductive polymer polypyrrole (PPy), and polypyrrole modified with cetyltrimethylammonium bromide (PPy.CTAB). The optimization of the experimental parameters was performed through univariate and multivariate approaches. The optimized condition was obtained with the use of 20 mg of Si3Py+Cl− as extraction phase; six extraction cycles with 700 μL of sample in each cycle and 15 s of extraction time; three desorption cycles with 100 μL of ACN (same aliquot) and 15 s of desorption time; and sample pH adjusted at 3.5 and addition of 15% (w/v) of NaCl in the sample. The methodology proposed exhibited environmentally-friendly aspects with a significantly reduced volume of organic solvent (only 100 µL) and a small amount of extraction phase (20 mg). In addition, the extraction phase employed exhibits a simple synthetic procedure, low cost, and high stability in organic solvent. Moreover, the method developed exhibits high throughput (extraction time of 6.5 min per sample), and robustness. The analytical figures of merit were obtained using hospital wastewater, and the values were very satisfactory. The correlation coefficients were higher than 0.9710. LODs and LOQs ranged from 0.030 µg L−1 to 1.510 µg L−1 and 0.10 µg L−1 to 5.00 µg L−1, respectively. Relative recoveries varied from 80 to 127%, and intra-day (n = 3) and inter-day (n = 9) precision was lower than 19%.

Preparation of amine-modified lignin and its applicability toward online micro-solid phase extraction of valsartan and losartan in urine samples

In the present work, with the focus on an environmentally-friendly approach, some gels were prepared by synthesizing amine-modified lignin, extracted from sugarcane bagasse, and further esterification and subsequent freeze-drying. These lignin-based gels were implemented as extractive phases in an online micro-solid phase extraction (μSPE) setup in conjunction with high performance liquid chromatography (HPLC) with UV detector. The developed method was used for analytical determination of valsartan and losartan in urine samples. To study the effect of the functionalization process, the efficiency of the unmodified lignin and the functionalized lignin were compared both in the absence and the presence of graphene oxide (GO), presumably as a suitable doping agent. Surprisingly, higher extraction efficiency for the functionalized lignin, compared to both unmodified lignin and GO was observed. The amination process for the prepared gel was analyzed and proved by CHNS elemental analysis and Fourier transform infrared (FT-IR) spectroscopy. The morphology of sorbet was investigated via scanning electron microscope (SEM) imaging and a nanoscale cauliflower feature was observed. The method was optimized and subsequently applied to the analysis of the urine samples. Limits of detection (LOD) of 8 and 6 µg L ^- 1, limits of quantification (LOQ) of 27 and 20 µg L ^- 1 and linear dynamic range (LDR) of 27-2000 and 20-2000 µg L ^- 1 with intraday relative standard deviations (RSD%) of 4 and 3% were obtained for valsartan and losartan, respectively. The whole online μSPE-HPLC setup was conveniently used for the analysis of a patient urine sample and a quantity of 352 μg L ^- 1 of losartan was found. Acceptable relative recoveries (109-108 and 95-94% for valsartan and losartan) revealed the analytical potential of the method for the determination of drugs in complex urine samples.

Nanoparticle coatings for stir bar sorptive extraction, synthesis, characterization and application

During the last ten years, number of articles published on synthesis and applications of nano-particles (NPs) have been increased by a factor of 40. One of the most interesting applications of NPs is their using as high capacity, robust and highly selective coatings for stir bar sorption extraction (SBSE). Utilizing NPs greatly promoted applications of SBSE and has gained importance on green sample preparation. In this article, all available literature on nano-coatings as media for microextraction by stir bar is reviewed. This includes non-functionalized NPs (mostly, metallic/metallic oxide and graphene based), functionalized coatings, and decorated coatings (both mono- and multifunctional). Various applications, advantages and disadvantages of each nano-coated prepared stir bar are discussed in detail along with critical evaluation of currently available methods.

Stir bar sorptive extraction and its application

Recent progress of stir bar sorptive extraction (SBSE) in the past six years is reviewed. The preparation methods including electrodeposition, self-assembly, solvent exchange, physical magnetic adsorption and electrostatic spinning, for the coated stir bar are summarized and compared, specifically for a specific material for coatings fabrication, e.g., carbon-based materials and metal organic frameworks. The emerging materials (e.g., graphene, graphene oxide, carbon nanotubes, monolith, metal-organic frameworks and porous organic polymers) applied for coated stir bar fabrication are one of the focus of this review, along with their respective advantages in extraction process and application in trace analysis. The development and application of extraction apparatus of SBSE are also involved. Based on these information, the development status and prospects of SBSE as an efficient sample pretreatment technique in real sample analysis are discussed.

A vinylpyrrolidone-based thin film microextraction in combination with direct solid-state spectrofluorimetry for determination of sartans in human plasma

A vinylpyrrolidone-ethylene glycol dimethacrylate-acrylic acid thin film was prepared on a polypropylene guard and its formulation was optimized for application in thin film microextraction followed by direct solid-state spectrofluorimetry method. The surface morphology, fluorescence property and extraction performance of the thin film were investigated systematically. The intra- and inter-batch reproducibilities of thin film fabrication were obtained 2.3 and 4.2%, respectively. The lifetime of each prepared thin film was 30 times with a relative standard deviation of less than 1.4%. The developed method was optimized for extraction of some sartans as angiotensin II receptors antagonist (including losartan, valsartan, and olmesartan) which have been used to control hypertension as the main causes of cardiovascular disease. The optimum extraction conditions achieved at 2- (for losartan) and 4- (for valsartan and olmesartan) sample pH, 500-rpm rotation rate and 30-min extraction time for all three analytes. At the optimum conditions, analyses of losartan, valsartan, and olmesartan were validated in the human plasma matrix. Broad linearity ranges with determination coefficients of more than 0.999 were achieved for each calibration curve. Limit of detection of the method was 0.5 ng mL^-1 for all three analytes. The intra- and inter-day accuracies and precisions of the developed method were evaluated in spiked plasma samples at three concentration levels of each analyte with high recoveries of 95-101% and relative standard deviations less than 6%. This method provides a simple, sensitive, fast, and high-throughput analysis method with the possibility of effective extraction of at least 40 samples simultaneously without the necessity of protein precipitating, desorption, and solvent evaporation steps.

Integrated Analytical Quality by Design (AQbD) Approach for the Development and Validation of Bioanalytical Liquid Chromatography Method for Estimation of Valsartan

The present studies describe the systematic development and validation of a simple, rapid, sensitive and cost-effective reversed-phase high-performance liquid chromatographic bioanalytical method for the estimation of valsartan in rat plasma employing analytical quality by design (AQbD) principles quality risk management was applied for identifying the critical method parameters (CMPs) and subsequently method optimization was performed employing Box–Behnken design by selecting mobile phase pH, flow rate and % organic modifier as the CMPs and evaluated for critical analytical attributes (CAAs) such as peak area, retention time, peak tailing and number of theoretical plates. The developed method was then transferred to bioanalysis, where liquid–liquid extraction process was used for separating the drug from rat plasma. The optimization of extraction process was performed with the help of face-centered cubic design by selecting centrifugation speed and centrifugation time as the CMPs for maximizing % recovery, signal-to-noise ratio and purity threshold of the drug peak after extraction as the CAAs. Optimum chromatographic solution was chosen by mathematical and graphical search techniques, and design space was demarcated. Validation studies performed for the developed method indicated linearity ranging between 5 and 100 ng.mL−1, whereas accuracy and precision study showed good percent recovery (99–102%) along with % relative standard deviation within ±2%. Sensitivity evaluation revealed limit of detection and limit of quantification were found to be 0.76 ng.mL−1 and 2.29 ng.mL−1, respectively. In a nutshell, the present work demonstrates significant merits of AQbD approach for holistic process understanding and analytical method development and validation with enhanced robustness and performance.

Synthesis of mesoporous silica for adsorption of chlordiazepoxide and its determination by HPLC: Experimental design

In this work, mesoporous silica (SBA-15-NH₂ ) was used as an efficient adsorbent for extraction of chlordiazepoxide from different samples based on dispersive nanomaterial-ultrasound assisted microextraction followed by high-performance liquid chromatography. The prepared sorbent was characterized by fourier transform infrared spectroscopy, scanning electron microscopy, low-angle X-ray diffraction, thermal analysis, and N₂ adsorption-desorption surface area measurement. Several variables affecting the extraction efficiency of the chlordiazepoxide, including the amounts of adsorbent, time of adsorption, pH and volume of desorption solvent were optimized by central composite design combined with desirability function. The values of variables were set as 10 mg of SBA-15-NH₂ , 15 min adsorption time, pH = 7.3 and 1 mL methanol. The linear response (0.998) was obtained in the range of 0.006-10 µgmL^-1 with detection limit 0.0014 µg/mL and extraction recovery was in the range of 91-96% with relative standard deviation < 6%.

Simultaneous magnetic dispersive micro solid phase extraction of valsartan and atorvastatin using a CMC-coated Fe3O4 nanocomposite prior to HPLC-UV detection: multivariate optimization

In this study, a sensitive, rapid, accurate and practical procedure is established for determination of atorvastatin and valsartan from human biological fluids by dispersive micro solid phase extraction (D-μ-SPE) combined with HPLC-UV detector.

Preparation of a magnetic molecularly imprinted polymer for the selective adsorption of chlordiazepoxide and its determination by central composite design optimized HPLC

Core–shell magnetic molecularly imprinted polymer nanoparticles (MMIP-NPs) were prepared and applied in the extraction of chlordiazepoxide from various samples.

Application of an optimized modified stir bar with ZnS nanoparticles loaded on activated carbon for preconcentration of carbofuran and propoxur insecticides in water samples and their HPLC determination

In this study, the stir bar was coated with the ZnS-NPs loaded on activated carbon (ZnS-AC) as well as [EMIM][PF₆] ionic liquid using sol gel technique was used for stir bar sorptive extraction (SBSE) of carbofuran and propoxur.

Magnetic solid phase extraction of polycyclic aromatic hydrocarbons and chlorophenols based on cyano-ionic liquid functionalized magnetic nanoparticles and their determination by HPLC-DAD

The extraction of CPs & PAHs on MNP@CN/IL provides highly percent recovery with good precision and enrichment factor of i.e., 100 & 200 for CPs and PAHs respectively.

Application of Ni:ZnS nanoparticles loaded on magnetic multi-walled carbon nanotubes as a sorbent for dispersive micro-solid phase extraction of phenobarbital and phenytoin prior to HPLC analysis: experimental design

Ni:ZnSNPs loaded on magnetic MWCNTs are introduced for dispersive micro-solid phase extraction for the first time.