Determination of remdesivir in human plasma using (deep eutectic solvent-ionic liquid) ferrofluid microextraction combined with liquid chromatography.

A microextraction technique based on ferrofluids was developed for the preconcentration and quantification of Remdesivir in human plasma samples. This method utilized a new type of magnetic colloids created by combining silica-coated magnetic particles with modified ionic liquid and natural hydrophobic deep eutectic solvent as the carrier liquid. The efficiency of the sorption and desorption steps was optimized using a chemometrics approach. Under the optimized conditions, the calibration curve exhibited linearity in the concentration range of 0.5 to 500.0 µg L-1, with a limit of detection and quantification of 0.2 and 0.5 µg L-1, respectively. The method precision was evaluated by assessing intra- and interday precision at three different analyte concentrations, yielding values of 8.9% and 16.8%, respectively. Moreover, the method accuracy fell within the range of 90.9% to 107.5%. This proposed method offers a green and environmentally friendly sample preparation technique for conducting pharmacodynamic, pharmacokinetic, and therapeutic drug monitoring studies of Remdesivir in biological fluids. Importantly, this technique eliminates the need for external energy sources or the use of dispersive solvents, providing a more efficient and sustainable approach.

Analysis of tamoxifen and its main metabolites in plasma samples of breast cancer survivor female athletes: Multivariate and chemometric optimization.

A sensitive method based on liquid chromatography combined with a diode array detector was developed and validated to simultaneously determine tamoxifen, and its active metabolites N-desmethyltamoxifen, 4-hydroxytamoxifen, and endoxifen in human plasma samples. The green and sustainable vortex-assisted dispersive liquid-phase microextraction technique based on the natural hydrophobic deep eutectic solvent was used for the extraction and preconcentration of the analytes. Chemometrics and multivariate analysis were used to optimize the independent variables including the type and volume of deep eutectic solvent, extraction time, and ionic strength. Under optimal conditions, calibration curves were linear in a suitable range with the lower limits of quantification (0.8-10.0 µg/L), which covered the relevant concentrations of the analytes in plasma samples for a clinical study. Intra- and interday precision evaluated at three concentrations for the analytes were lower than 8.2 and 12.1%, respectively. Accuracy was in the range of 94.9-104.7%. The applicability of the developed method on human plasma samples illustrated the range 45.1-72.8, 98.4-128.3, 0.9-1.2, and 2.7-6.1 µg/L for tamoxifen, N-desmethyltamoxifen, 4-hydroxytamoxifen, and endoxifen, respectively. The validated method can be effective for the pharmacokinetics, pharmacodynamics, and therapeutic drug monitoring studies of tamoxifen and its main metabolites in biological fluids.

Vortex- assisted liquid- liquid microextraction for the trace determination of potassium bromate in flour food products.

Potassium bromate, also reported as a carcinogenic agent, commonly functions to improve flour in the baking industry to increase bread volume. In this study, a green and novel preconcentration and microextraction method, termed as vortex assisted liquid-liquid microextraction combined with UV-Vis spectrophotometry was developed and utilized for trace determination of Potassium Bromate in food samples. Furthermore, various chemometric methods have been used. Under optimum conditions, the linearity range was obtained in the range between 0.02 and 2 µg/mL. Using the proposed analytical approach, the detection limits and quantitation of KBrO3 were 0.02 and 0.07 µg/mL, respectively. A pre-concentration factor of 22.2 was reported. The precision of the method was evaluated in the terms of repeatability and reproducibility and expressed by the relative standard deviation; the levels of them were considerably higher than 5.07 and 4.8%. The proposed approach was applied to the determination of trace bromate in different flour products.

Fabrication of superparamagnetic adsorbent based on layered double hydroxide as effective nanoadsorbent for removal of Sb (III) from water samples.

In this study, the superparamagnetic adsorbent as Fe@Mg-Al LDH was synthesised by different methods with two steps for the removal of heavy metal ions from water samples. An easy, practical, economical, and replicable method was introduced to remove water contaminants, including heavy ions from aquatic environments. Moreover, the structure of superparamagnetic adsorbent was investigated by various methods including Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and vibrating sample magnetometer. For better separation, ethylenediaminetetraacetic acid ligand was used, forming a complex with antimony ions to create suitable conditions for the removal of these ions. Cadmium and antimony ions were studied by floatation in aqueous environments with this superparamagnetic adsorbent owing to effective factors such as pH, amount of superparamagnetic adsorbent, contact time, sample temperature, volume, and ligand concentration. The model of Freundlich, Langmuir, and Temkin isotherms was studied to qualitatively evaluate the adsorption of antimony ions by the superparamagnetic adsorbent. The value of loaded antimony metal ions with Fe@Mg-Al LDH was resulted at 160.15 mg/g. The standard deviation value in this procedure was found at 7.92%. The desorption volume of antimony metal ions by the adsorbent was found to be 25 ml. The thermodynamic parameters as well as the effect of interfering ions were investigated by graphite furnace atomic absorption spectrometry.

Strategies to improve the challenges of classic dispersive liquid-liquid microextraction for determination of the parabens in personal care products-One step closer to green analytical chemistry.

Gas flow-assisted dispersive liquid-phase microextraction based on deep eutectic solvent was used to determine parabens in personal care products such as mouthwash, lidocaine gel, aloe vera gel, and skin tonic. A homemade extraction device was innovated, in which by passing the stream of gas bubbles through the deep eutectic solvent a thin layer of the extraction phase is coated on the surface of the bubbles. The extraction is finally achieved when the bubbles are going up through the sample. The single-factor experiments and response surface methodology were applied to optimize the independent variables. The linear range of the method was 0.5 to 1000 µg L-1, the coefficient of determination for the goal analytes was higher than 0.9989, the instrumental limit of detections were in the range 0.2-0.3 µg L-1, and the instrumental limit of quantifications were in the range 0.5-1.1 µg L-1, the relative standard deviations were <5.2% for repeatability and <11.2% for intermediate precision, and the enrichment factors were 66 to 87 obtained under the optimized conditions. A spiking approach by means of standard material was used to estimate accuracy. The relative recoveries were in the range 95.8-105.2%. By using mentioned strategies, the organic waste and energy consumption reduced, toxic reagents replaced with safer ones, and operator safety enhanced. Accordingly, these benefits have been simultaneously attained and, the proposed method was one step closer to automation and sustainable analytical chemistry.

Bursting-bubble flow microextraction combined with gas chromatography to analyze organophosphorus pesticides in aqueous samples.

Bubble-bursting flow microextraction combined with gas chromatography as a green and sustainable microextraction method is used to determine some organophosphorus pesticide residues in water samples. The extraction process occurs at the surface of liquid-gas contact, where the analytes interact with the gas molecules in the bubble. The analytes are transferred to the surface of the sample solution by moving the gas bubbles upwards. The bursting of gas bubbles causes the analytes to disperse in the headspace. Eventually, they are collected for injection into the chromatography system. A one-factor-at-one-time approach was applied to optimize the independent variables in the proposed method. Validation studies were performed according to reliable guidelines. Under optimal conditions, the method indicated a dynamic linear range from 1.0 to 100.0 µg/L. The limit of detection and quantification of the method was 0.29-0.38 and 1.21-1.70 µg/L, respectively. The proposed method was successfully utilized to determine malathion, diazinon, profenofos, and ethion as the target analytes in various water samples with satisfactory relative recoveries ranged from 90.1 to 102.2%.

Validation of chemometric-assisted single-drop microextraction based on sustainable solvents to analyze polyaromatic hydrocarbons in water samples.

Chemometric and statistic approaches were applied to optimize and validate headspace-single drop microextraction-based deep eutectic solvents combined with gas chromatography-mass spectrometry. The proposed technique was used for the pre-concentration, separation, and detection of polyaromatic hydrocarbons in aqueous samples. The efficacy of the independent variables on the extraction efficiency was studied via chemometric methods in two steps. The method exhibits good linearity for the analytes (R2 ≥ 0.9989). Under optimal conditions, the analytical signal was linear in the range of 0.01-50 µg L-1. The limit of detection and limit of quantitation were evaluated in the concentration range of 0.003-0.012 and 0.009-0.049 µg L-1, respectively. The precision consisting of repeatability and reproducibility were assessed by estimating the relative standard deviation (RSD%), and their values were found to be lower than 7.1% and 11.7%, respectively. Consequently, the proposed procedure was used to extract and analyze 19 polyaromatic hydrocarbons in real aqueous samples, which demonstrated satisfactory recoveries (94.40-105.98%).

Deep eutectic solvent-based headspace single-drop microextraction of polycyclic aromatic hydrocarbons in aqueous samples.

An improved deep eutectic solvent (DES)-based headspace single-drop microextraction procedure has been developed as a green procedure for gas chromatography-mass spectrometric analysis of polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. The stability of the micro-drop was significantly improved using a DES as an extraction phase and a bell-shaped tube as a supporter. These strategies helped to perform the extraction process in higher temperatures and stirring rates. Finally, the back-extraction of the analytes into a proper solvent that is compatible with the chromatography system was applied. The efficacy of the independent variables on the extraction efficiency was evaluated via chemometric methods in two steps. The best result was obtained with choline chloride-oxalic acid at the molar ratio of 1:2, a stirring speed of 2000 rpm for 10 min as well as a sample temperature of 50 °C and with ionic strength prepared by using a 10% (w/v) NaCl. The method indicated a good linearity for the analytes (R2≥0.9989). Under optimal conditions, the analytical signal was linear in the range of 0.01-50 µg L-1. Limit of detection (LOD) and limit of quantification (LOQ) were evaluated at the concentration levels of 0.003-0.012 and 0.009-0.049 µg L-1, respectively. Intraday and interday precision for all targeted compounds was less than 7.2% and 11.3%, respectively. Consequently, the proposed procedure was efficiently applied to extract and analyze the 16 target compounds in real aqueous samples representing satisfactory recoveries (94.40-105.98%).

Salting-out strategy for speciation of selenium in aqueous samples using centrifuge-less dispersive liquid-liquid microextraction.

The centrifuge-less dispersive liquid-liquid microextraction (DLLME) technique was used to separate selenium species in aqueous samples. According to the salting-out effect, a simple approach was used to eliminate the centrifugation step. The optimization of the independent variables was performed using chemometric methods. Under optimal conditions, this methodology was statistically validated. The linearity was between 20 and 300 µg L-1. The limit of detection and quantification were calculated 3.4 µg L-1 and 10.4 µg L-1, respectively. The values of reproducibility and repeatability were determined ≤ 9.5% and ≤ 6.4, respectively. The possibility of the method was successfully assessed by analyzing the analytes in real samples clarified satisfactory recoveries (98.1-101.4% for Se (IV) and 98.4-101.5% for Se (VI)).

Sustainable and green microextraction of organophosphorus flame retardants by a novel phosphonium-based deep eutectic solvent.

Based on the solidification of a hydrophobic deep eutectic solvent in air-assisted liquid phase microextraction combined with gas chromatography and mass spectrometry, a green and sustainable microextraction technique was developed for extracting, separating, and detecting organophosphorus flame retardants in aqueous samples. In this study, some strategies were considered for overcoming or improving the challenges of conventional solvent microextraction procedures. In addition, a hydrophobic deep eutectic solvent with a freezing point near the ambient temperature was employed as an extraction phase, the dispersive solvent was substituted by the syringe pump process, and the centrifugation step was omitted by using salting-out phenomenon. Further, the effect of the main independent variables was evaluated by using the chemometric methods in order to maximize the extraction efficiency of the procedure. Under optimal conditions, the calibration model was linear in the range of 0.01-25.0 µg/L. Limits of detection and quantitation were assessed at the concentration levels of 2-23 and 9-65 ng/L, respectively. The precision involving repeatability and reproducibility was evaluated by estimating the relative standard deviation, the levels of which were <6.6 and <8.7%, respectively. The applicability of the method was successfully evaluated by analyzing the target analytes in real aqueous samples, which illustrated satisfactory recoveries (95-104.61%).

A green dispersive liquid phase microextraction technique based on the solidification of switchable hydrophilic fatty acid for determination of polynuclear aromatic hydrocarbons in aqueous samples.

A green dispersive liquid phase microextraction approach based on the solidification of switchable hydrophilic fatty acid as an extraction phase has been developed for the determination of 16 priority polynuclear aromatic hydrocarbons (PAHs) in aqueous samples. In this study, the centrifugation step was omitted by the applying salting-out phenomenon. The influence of main variables on the efficiency of the procedure was studied by chemometric methods. Under optimal conditions, the completion time for extraction was less than 1 min, and the detector response was linear in the range of 0.1-250 µg L-1. Limit of detection and limit of quantitation were estimated as the concentration range of 0.01-0.14 µg L-1 and 0.03-0.47 µg L-1, respectively. The precision consists of repeatability and reproducibility, which were determined by calculating the relative standard deviation percent; their values were less than 7.2% and 10.5%, respectively. Applicability of the developed procedure was successfully evaluated for the analysis of PAHs in different water samples.

Overcoming the challenges of conventional dispersive liquid-liquid microextraction: analysis of THMs in chlorinated swimming pools.

A rapid, simple, and sensitive approach to the analysis of trihalomethanes (THMs) in swimming pool water samples has been developed. The main goal of this study was to overcome or to improve the shortcomings of conventional dispersive liquid-liquid microextraction (DLLME) and to maximize the realization of green analytical chemistry principles. The method involves a simple vortex-assisted microextraction step, in the absence of the dispersive solvent, followed by salting-out effect for the elimination of the centrifugation step. A bell-shaped device and a solidifiable solvent were used to simplify the extraction solvent collection after phase separation. Optimization of the independent variables was performed by using chemometric methods in three steps. The method was statistically validated based on authentic guidance documents. The completion time for extraction was less than 8 min, and the limits of detection were in the range between 4 and 72 ng L-1. Using this method, good linearity and precision were achieved. The results of THMs determination in different real samples showed that in some cases the concentration of total THMs was more than threshold values of THMs determined by accredited healthcare organizations. This method indicated satisfactory analytical figures of merit. Graphical Abstract A novel green microextraction technique for overcoming the challenges of conventional DLLME. The proposed procedure complies with the principles of green/sustainable analytical chemistry, comprising decreasing the sample size, making easy automation of the process, reducing organic waste, diminishing energy consumption, replacing toxic reagents with safer reagents, and enhancing operator safety.

Monitoring Pb in Aqueous Samples by Using Low Density Solvent on Air-Assisted Dispersive Liquid-Liquid Microextraction Coupled with UV-Vis Spectrophotometry.

In this study, AA-DLLME combined with UV-Vis spectrophotometry was developed for pre-concentration, microextraction and determination of lead in aqueous samples. Optimization of the independent variables was carried out according to chemometric methods in three steps. According to the screening and optimization study, 86 µL of 1-undecanol (extracting solvent), 12 times syringe pumps, pH 2.0, 0.00% of salt and 0.1% DDTP (chelating agent) were chosen as the optimum independent variables for microextraction and determination of lead. Under the optimized conditions, R = 0.9994, and linearity range was 0.01-100 µg mL-1. LOD and LOQ were 3.4 and 11.6 ng mL-1, respectively. The method was applied for analysis of real water samples, such as tap, mineral, river and waste water.

Lead Quantification in Urine Samples of Athletes by Coupling DLLME with UV-Vis Spectrophotometry.

Urine lead level is one of the most employed measures of lead exposure and risk. The urine samples used in this study were obtained from ten healthy male cyclists. Dispersive liquid-liquid microextraction combined with ultraviolet and visible spectrophotometry was utilized for preconcentration, extraction, and determination of lead in urine samples. Optimization of the independent variables was carried out based on chemometric methods in three steps. According to the screening and optimization study, 133 µL of CCl4 (extracting solvent), 1.34 mL ethanol (dispersing solvent), pH 2.0, 0.00 % of salt, and 0.1 % O,O-diethyl dithiophosphoric (chelating agent) were used as the optimum independent variables for microextraction and determination of lead. Under the optimized conditions, R 2 was 0.9991, and linearity range was 0.01-100 µg L-1. Precision was evaluated in terms of repeatability and intermediate precision, with relative standard deviations being <9.1 and <15.3 %, respectively. The accuracy was estimated using urine samples of cyclists as real samples and it was confirmed. The relative error of ≤5 % was considered significant in the method specificity study. The lead concentration mean for the cyclists was 3.79 µg L-1 in urine samples. As a result, the proposed method is a robust technique to quantify lead concentrations higher than 11.6 ng L-1 in urine samples.

Liquid phase microextraction-ion exchange-high performance thin layer chromatography for the preconcentration, separation, and determination of plasticizers in aqueous samples.

Liquid phase microextraction combined with ion-exchange-high performance thin layer chromatography has been developed for analysis of four plasticizers in aqueous samples. After their preconcentration by liquid phase microextraction, fast separation on thin layers of inorganic ion-exchanger stannic silicate has been developed using a mixture of toluene + ethyl acetate (10:1, v/v) as mobile phase. Consequently, densitometric quantitative determination of the plasticizers has been made at λ = 280 nm in reflection-absorption mode by Camag TLC scanner-3. The effects of type and volume of extraction solvent, stirring rate, extraction time, and ionic strength in the microextraction method have been also evaluated and optimized. The results show that the proposed method provides enhanced accuracy, linear range, LOD, and LOQ, and is very effective for analyzing the target compounds in water samples. Under the optimized conditions, preconcentration factor of 149-279 and extraction efficiency of 31-59% have been obtained. Repeatability (5.67-7.26%) and intermediate precision (6.21-8.17%) were in acceptable range. The relative recovery obtained for each analyte in different water samples was higher than 82.3% at three fortification levels with RSD <7.9%.

Determination of phenolic compounds in environmental water samples after solid-phase extraction with ß-cyclodextrin-bonded silica particles coupled with a novel liquid-phase microextraction followed by gas chromatography-mass spectrometry.

A novel approach for the sample pre-treatment and determination of eight phenolic compounds in environmental water samples has been developed by hyphenating solid-phase extraction (SPE) and liquid-phase microextraction (LPME) techniques based on solid organic drop combined with gas chromatography-mass spectrometry detection (GC-MS). After pre-concentration and purification of the sample through column containing 60 mg of ß-cyclodextrin-bonded silica particles as stationary phase, under the optimum conditions, LPME technique has been performed on the eluent solution. Under the selected conditions, limit of detection (LOD) of 0.002-0.04 µg/L (S/N=3), limit of quantification (LOQ) of 0.007-0.15 µg/L (S/N=10), pre-concentration factor of 752-3135 and linearity range of 0.01-25 µg/L have been obtained. A reasonable repeatability (RSD≤9.5%, n=5) with satisfactory coefficient of determination has been obtained between 0.9981 and 0.9997. The relative recoveries of the waste, sea, river and well water samples were higher than 79%.

ß-cyclodextrin-bonded silica particles as novel sorbent for stir bar sorptive extraction of phenolic compounds.

A stir bar coated with ß-cyclodextrin-bonded-silica (CDS) as novel sorbent has been developed and used to analyze seven phenolic compounds in aqueous samples, followed by thermal desorption and gas chromatography-mass spectrometric detection. Significant parameters affecting sorption process such as the time and temperature of sorption and desorption, ionic strength, pH and stirring rate have been optimized and discussed. The coating has a high thermal stability up to 300°C and long application lifetime (80 times). The porous structure of CDS coating provides high surface area and allows high extraction efficiency. Under the selected conditions, linearity range of 0.1-400 µg/L, limit of quantifications of 0.08-3.3 µg/L and method detection limits of 0.02-1.00 µg/L have been obtained. A satisfactory repeatability (RSD ≤ 6.5, n = 7) with good linearity (0.9975 ≤ r(2) ≤ 0.9996) of results illustrated a good performance of the present method. The recovery of different natural water samples was higher than 81.5%.

Pre-concentration of phenolic compounds in water samples by novel liquid-liquid microextraction and determination by gas chromatography-mass spectrometry.

Pre-concentration and determination of 8 phenolic compounds in water samples has been achieved by in situ derivatization and using a new liquid-liquid microextraction coupled GC-MS system. Microextraction efficiency factors have been investigated and optimized: 9 microL 1-undecanol microdrop exposed for 15 min floated on surface of a 10 mL water sample at 55 degrees C, stirred at 1200 rpm, low pH level and saturated salt conditions. Chromatographic problems associated with free phenols have been overcome by simultaneous in situ derivatization utilizing 40 microL of acetic anhydride and 0.5% (w/v) K(2)CO(3). Under the selected conditions, pre-concentration factor of 235-1174, limit of detection of 0.005-0.68 microg/L (S/N=3) and linearity range of 0.02-300 microg/L have been obtained. A reasonable repeatability (RSD< or =10.4%, n=5) with satisfactory linearity (0.9995> or =r(2)> or =0.9975) of results illustrated a good performance of the present method. The relative recovery of different natural water samples was higher than 84%.

beta-Cyclodextrin-bonded silica particles as the solid-phase extraction medium for the determination of phenol compounds in water samples followed by gas chromatography with flame ionization and mass spectrometry detection.

A new absorbent for solid-phase extraction (SPE) was prepared by a beta-cyclodextrin bonded silica stationary phase (CDS) has been applied to determine the concentrations of phenol compounds in water samples. SPE of selected phenolic compounds from aqueous samples were performed using 250 mg CDS. The determination was subsequently carried out by gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS). Compared with available SPE, the CDS showed high sensitivity and fast velocity of mass transfer for phenolic compound because of its porous structure of beta-cyclodextrin. The relative standard deviation (RSD) for river water sample spiked with phenolic compounds at sub-ppb level was lower than 10% and limit of detection (LOD) for these compounds were between 10 and 100 ng l(-1).