Preparation of a new composite based on multilayer fullerene with mesoporous carbon nitride and its application in the extraction of tacrolimus and everolimus from plasma prior to LC-MS/MS analysis.

The development of new and efficient adsorbents for dispersive solid-phase extraction method, particularly prior to chromatography analysis, is increasing. In particular, this method is recommended for use before biological sample analysis. In this work, a new composite was prepared from mesoporous carbon nitrides and carbon nano-onions and was utilized for the extraction of tacrolimus and everolimus from plasma samples prior to high-performance liquid chromatography-tandem mass spectrometry analysis. To achieve this aim, first, mesoporous carbon nitrides and carbon nano-onions were synthesized separately and mixed at optimized proportions. Subsequently, a suitable amount of the prepared composite (5 mg) was added to 2 mL of sample solution containing the analytes under vortexing. Next, the extracted analytes were eluted using acetonitrile. The approach was linear within the ranges of 1.0-500 and 0.51-500 ng mL-1 for tacrolimus and everolimus, respectively. Sensitive limits of detection (0.31 and 0.15 ng mL-1 for tacrolimus and everolimus, respectively), acceptable relative standard deviations (intra- and inter-day precisions of ≤5.6% and high extraction recoveries of 71.0% and 83.0% for tacrolimus and everolimus, respectively) were obtained. The results showed that the method can be successfully applied in the simultaneous extraction of the studied analytes from plasma.

Application of cobalt-cerium-iron ternary layered double hydroxide for extraction of perfluorooctane sulfonate followed by HPLC-MS/MS analysis.

Herein, Ce-doped CoFe layered double hydroxide (LDH), noted as CoCeFe ternary LDH, was prepared using the co-precipitation route. Prosperous synthesis of CoFe LDH and successful partial replacement of iron cations with cerium cations in CoCeFe ternary LDH were confirmed by X-ray diffraction patterns, energy-dispersive X-ray spectroscopy, and elemental dot-mapping images. Nanosheet morphology was recognized for both CoFe LDH and CoCeFe ternary LDH from scanning electron microscopy and transmission electron microscopy micrographs. In the following, a dispersive solid phase extraction (DSPE) method was developed using the synthesized CoCeFe ternary LDH as a sorbent for extracting perfluorooctanesulfonic acid (PFOS) from wastewater samples. For the selective analysis of PFOS, high-performance liquid chromatography-tandem mass spectroscopy (HPLC-MS/MS) in multiple reaction monitoring mode was used. Analytical parameters such as the limit of detection equal to 0.02 µg/L, with a linear range of 0.05-300 µg/L, the limit of quantification equal to 0.05 µg/L, and an enrichment factor equal to 23.3 were achieved for PFOS at the optimized condition (sorbent: 5 mg of CoCeFe ternary LDH, eluent type and volume: 150 µL mobile phase, pH: 3, adsorption time: 3 min, and desorption time: 5 min). The developed strategy for the analysis of PFOS was tested in real wastewater samples, including copper mine and petrochemical wastewater. The amount of analytes in real samples was calculated using the standard addition method, and good relative recovery in the range of 86%-105% was obtained. The main novelty of this research is the application of CoCeFe ternary LDH to extract the PFOS from wastewater using the DSPE method for determination by HPLC-MS/MS.

Extraction of Covid-19 drug (Favipiravir) from plasma samples by yolk-shell mesoporous silica before HPLC-MS/MS determination.

In this work, a simple and inexpensive dispersive solid phase extraction method using SiO2 @MCM-41-Co3O4 yolk shell as a sorbent was developed for the extraction of favipiravir from plasma samples. The sorbent was synthesized with a simple and novel method. Optimization of the extraction procedure was performed using one parameter at a time strategy. For selective measurement of favipiravir in real samples, multiple reaction monitoring mode in high-performance liquid chromatography-tandem mass spectrometry was used. The synthesized sorbent presented a high adsorption capacity for favipiravir due to its mesoporous structure and different interactions. After optimization of effective parameters including the amount of sorbent, pH, and adsorption and desorption times, the analytical parameters of the method were evaluated. The developed method exhibited a wide linear range from 0.50 to 1000 µg/L. The detection limit and quantification limit of the method were 0.15 and 0.50 µg/L, respectively. The relative standard deviation of the method was obtained by using intra- and inter-day tests, and in both cases, it was less than 6.0%. Finally, the method was successfully used to measure favipiravir in plasma samples with relative recoveries in the range of 87-105%.

CuBTC metal organic framework-based dispersive solid phase extraction of cyclosporine and tacrolimus from plasma samples prior to determination by high performance liquid chromatography-tandem mass spectrometry.

Immunosuppressive drugs are prescribed to reduce the immune system of persons who are undergoing organ transplants. The concentration of these drugs in blood and plasma samples must be accurately and precisely determined during immunosuppressive therapy due to their significant side effects. In this study, a metal organic framework-based dispersive solid phase extraction method was developed for the extraction of tacrolimus and cyclosporine from plasma samples before their determination by high performance liquid chromatography-tandem mass spectrometry. For this purpose, CuBTC metal organic framework nanoparticles were prepared by a hydrothermal approach and they were used as the sorbent in the extraction procedure. The adsorbed analytes were eluted by a suitable organic solvent and then more concentrated by evaporation of the eluate. All of the effective parameters of the method including sorbent amount, adsorption time, eluent type, desorption time, eluent volume, and sample solution pH were studied and optimized. They were obtained 5 mg, 5 min, acetone, 5 min, 300 µL, and 5, respectively. Under optimal conditions, the developed method was validated and the data showed that the linear range, the limit of detection, the limit of quantification, the coefficient of determination, the enrichment factor, and relative standard deviation values were 1-1000 ng mL-1, 0.30 ng mL-1, 0.5 ng mL-1, 0.99, 15.6, and 5.8 % for tacrolimus and 0.8-500 ng mL-1, 0.25 ng mL-1, 0.4 ng mL-1, 0.99, 17, and 5.6 % for cyclosporine, respectively. Finally, the method was successfully used in the determination of the studied drugs in plasma samples.

Application of polysaccharide biopolymers as natural adsorbent in sample preparation.

Preparing samples for analyses is perhaps the most important part to analyses. The varied functional groups present on the surface of biopolymers bestow them appropriate adsorption properties. Properties like biocompatibility, biodegradability, presence of different surface functional group, high porosity, considerable absorption capacity for water, the potential for modification, etc. turn biopolymers to promising candidates for varied applications. In addition, one of the most important parts of determination of an analyte in a matrix is sample preparation step and the efficiency of this step in solid phase extraction methods is largely dependent on the type of adsorbent used. Due to the unique properties of biopolymers they are considered an appropriate choice for using as sorbent in sample preparation methods that use from a solid adsorbent. Many review articles have been published on the application of diverse adsorbents in sample preparation methods, however despite the numerous advantages of biopolymers mentioned; review articles in this field are very few. Thus, in this paper we review the reports in different areas of sample preparation that use polysaccharides-based biopolymers as sorbents for extraction and determination of diverse organic and inorganic analytes.

UiO-66-based metal-organic framework for dispersive solid-phase extraction of vanillylmandelic acid from urine before analysis by capillary electrophoresis.

Dispersive solid-phase extraction (DSPE) was developed for the extraction of vanillylmandelic acid (VMA) in urine samples prior to capillary electrophoresis with diode array detection (CE-DAD). Extraction of VMA by DSPE was carried out by direct addition of 7.5 mg of synthesized amino-functionalized UiO-66 (Zr) metal-organic framework adsorbent into the 5 mL sample solution (pH 4.0), followed by sonication and centrifugation. The supernatant layer was discarded, then the sedimented adsorbent was eluted using borate buffer (75 mM, pH 10). Effective extraction parameters including the amount of adsorbent, sample pH, adsorption and desorption time, type, volume and pH of eluent, and type of adsorbent dispersion method were systematically investigated. Under the optimized conditions, linearity of the method was from 40 to 2000 µg L-1 with a correlation coefficient over 0.9948. The method detection and quantification limits were 12 and 40 µg L-1, respectively. The relative standard deviations for intra-and inter-day precision were 2.4 and 2.8% (n = 5), respectively. The extraction recovery and enrichment factor values were 90% and 9.0 respectively.

A mixed deep eutectic solvents-based air-assisted liquid-liquid microextraction of surfactants from exhaled breath condensate samples prior to HPLC-MS/MS analysis.

A ternary solvent system-based air-assisted liquid-liquid microextraction procedure was developed for the extraction of three surfactants from exhaled breath condensate samples prior to their determination by high performance liquid chromatography-tandem mass spectrometry. In this approach, different deep eutectic solvents were synthesized based on phosphocholine chloride and fatty acids and their mixtures were used as the extraction solvents to effective extraction of the analytes. To obtain the optimum composition of the extraction solvents, a simplex centroid design approach was used. Then the effective parameters were studied by response surface methodology using central composite design. The obtained data after optimization showed that 6 times was the best extraction time for the developed procedure. When the sample solution pH was adjusted at 3.7, the method reached to higher extraction efficiency which can be related to the fact that the analytes were in the protonated forms. Increasing the sample solution temperature up to 50 °C enhanced the migration rate of the analytes into the extraction solvent and the method efficacy was increased. Also addition of sodium chloride at 2.8% (w/v) had a positive effect on the method efficiency which can be related to decreasing the analytes solubility in the sample solution. Under optimal conditions, the method showed satisfactory coefficient of determination (≥0.9979), low limit of detection (0.12-0.23 ng mL-1) and quantification (0.39-0.76 ng mL-1), acceptable repeatability in deionized water (relative standard deviation ≤ 8.2%) and in exhaled breath condensate (relative standard deviation ≤ 7.2%), and acceptable extraction recovery (75-86%) and enrichment factor (71-86). Considering these results, the developed method provided a quick and efficient way to determine surfactants in the exhaled breath condensate collected from expiratory circuit of the mechanical ventilator. It can be used in drug monitoring and clinical studies.

Application of microcrystalline cellulose as an efficient and cheap sorbent for the extraction of metoprolol from plasma and wastewater before HPLC-MS/MS determination.

A dispersive solid-phase extraction method based on a new sorbent has been performed on plasma and wastewater samples to determine metoprolol by high-performance liquid chromatography-tandem mass spectrometry. In this study, the analyte was adsorbed from the samples onto microcrystalline cellulose as a green and efficient sorbent and then eluted for use in the determination step. In the mass spectrometer, the analyte was detected in the positive mode and selectivity of the analysis was increased by sequential mass analysis through multiple reaction monitoring. All of the effective parameters in the extraction of metoprolol from plasma and wastewater were optimized. Under optimal conditions the method was linear in the ranges of 1-1,000 and 0.1-1,000 ng/ml in plasma and wastewater samples, respectively. The detection limits of the method were 0.30 and 0.03 ng/ml in plasma and wastewater samples, respectively. The data showed that the method provides low detection limit, wide linear range, good precision and high extraction recovery. Finally several plasma and wastewater samples were successfully analyzed using the method. The use of a small amount of a green and inexpensive sorbent and a low volume of plasma without the need for further pretreatment steps are the main advantages of the method.

Evaluation of MXene as an adsorbent in dispersive solid phase extraction of several pesticides from fresh fruit juices prior to their determination by HPLC-MS/MS.

This study aimed to introduce a dispersive solid phase extraction method based on MXene nanoparticles as a novel sorbent for the simultaneous extraction and determination of twelve pesticides from fresh fruit juices. In the following, a high performance liquid chromatography-tandem mass spectrometry was used for their determination in the samples. In this method, two-dimensional nanomaterials of Ti2AlC were exfoliated in an acidic solution and then they were added into the sample solution. To enhance the sample solution and sorbent contact area, the mixture was vortexed for a few minutes. Then the adsorbed analytes onto the sorbent were eluted using acetone and then analyzed. Under optimal conditions, the calibration curves of the method were linear within the range of 3.0-1000 µg L-1. The limits of detection, intra- and inter-day relative standard deviations, and extraction recoveries were in the ranges of 0.08-1.0 µg L-1, 2.5-4.2%, 2.5-5.5%, and 69-75%, respectively. Performing the method verified the presence of some of the analytes in several samples. This method can help to monitor pesticides in juice samples as well as to improve our understanding the safety of foods.

In situ adsorbent formation based dispersive micro-solid phase extraction using a deep eutectic solvent as an elution solvent for the extraction of some pesticides from honey samples prior to GC-MS analysis.

In this work, a simple, inexpensive, green, and fast dispersive micro-solid phase extraction method has been developed for the extraction of several pesticides from honey samples. In this approach, a solution of curcumin was prepared in ethanol and it was dispersed into a sample solution with the aid of a syringe. Curcumin was precipitated in the sample solution as tiny particles and the analytes were adsorbed onto them. After centrifugation the adsorbed analytes were eluted with tetrabutylammonium chloride:dichloroacetic acid deep eutectic solvent. The dissolved analytes in the deep eutectic solvent were analyzed by gas chromatography-mass spectrometry. Parameters affecting the extraction efficiency of the method including sorbent amount, dispersive solvent type and volume, elution solvent type and volume, salting out effect, and sonication time were investigated. Extraction recovery of the method was obtained in the range of 70-83%. Also wide calibration ranges and low detection limits (0.22-0.81 ng g-1) were obtained. Relative standard deviation values for intra- and inter-day precisions were ≤10.2% for all analytes at a concentration of 5 ng g-1 of each (n = 6). Finally, ten honey samples were analyzed and data showed that all of the studied samples were free of the analytes.

Application of curcumin as a green and new sorbent in deep eutectic solvent-based dispersive micro-solid phase extraction of several polycyclic aromatic hydrocarbons from honey samples prior to gas chromatography-mass spectrometry determination.

A green, simple, and efficient dispersive micro-solid phase extraction method was developed for the extraction of polycyclic aromatic hydrocarbons from honey samples. In this method, for the first time, curcumin was used as an efficient and green sorbent to extract the analytes from the sample. After that the adsorbed analytes were eluted using a deep eutectic solvent prepared by mixing tetrabutylammonium chloride: ethylene glycol and analyzed by gas chromatography-mass spectrometry. Important experimental factors affecting adsorption and desorption steps of the method were optimized and under optimal experimental conditions, low limits of detection (0.14-0.37 ng/g) and quantification (0.49-1.3 ng/g), wide linear range (1.3-500 ng/g) with a coefficient of determination ≥0.994 were obtained. Relative standard deviation values for intra- and interday precisions were ≤7.5% for all of the analytes at a concentration of 2 ng/g for each analyte (n = 6). Extraction recovery of the method was in the range of 72-81%. Finally, 20 honey samples were analyzed and the analytes were successfully detected. The method is environment friendly because of the use of curcumin as a sorbent. Also, biodegradability of the used deep eutectic solvent components is another advantage of the method.

Application of magnetic carbon nano-onions in dispersive solid-phase extraction combined with DLLME for extraction of pesticide residues from water and vegetable samples.

A dispersive solid-phase microextraction method based on magnetic carbon nano-onions (MCNOs) was developed for the extraction and preconcentration of some pesticides from water and vegetable samples. For more cleanup and preconcentration, a dispersive liquid-liquid microextraction (DLLME) method was employed after performing the first step. In this method, firstly, MCNOs were prepared and then used for adsorption of the analytes from the sample solution. After that, the adsorbed analytes were eluted with an appropriate water-miscible organic solvent and used as a dispersive solvent in the following DLLME procedure. The extracted analytes were quantified by gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode. Various factors affecting the method efficiency such as sorbent weight, salt effect, pH, temperature, and type and volume of eluent and extraction solvent were optimized. This method showed wide linear ranges with a coefficient of determination ≥ 0.994, and low limits of detection (0.001-0.005 ng mL-1) and quantification (0.003-0.019 ng mL-1) under optimal conditions. Also, a good precision (relative standard deviation ≤ 8.6%) for five replicates and a satisfactory accuracy (mean relative recoveries between 82 and 99%) were obtained. It can be considered as an efficient and environment friendly method for the extraction of analytes from vegetable and fruit juices and water samples.

Electrochemical Oxidation and Determination of Antiviral Drug Acyclovir by Modified Carbon Paste Electrode With Magnetic CdO Nanoparticles.

With the development of nanomaterials in electrochemical sensors, the use of nanostructures to modify the electrode surface has been shown to improve the kinetics of the electron transfer process. In this study, a sensor was developed for the electrochemical determination of Acyclovir (ACV) based on the modified carbon paste electrode (CPE) by CdO/Fe3O4. The magnetic CdO nanoparticles characterization was studied by energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). To study of the modified CPE surface morphology, scanning electron microscopy (SEM) was used. At the optimal conditions, a noteworthy enhancement in the electrochemical behavior of ACV was observed at the surface of the modified CPE compared to the unmodified CPE. A detection limit of 300 nM and a linear range of 1-100 µM were obtained for the quantitative monitoring of ACV at the modified CPE surface using differential pulse voltammetry (DPV) in phosphate buffer. The RSD% (relative standard deviation) of the electrode response was <4.3% indicating the development of a high precision method. Also, satisfactory results were obtained in the determination of ACV with the modified electrode in tablet, blood serum, and urine samples with a satisfactory relative recovery (RR%) in the range of 94.0-104.4%.

A monolithic graphitic carbon nitride/polyethersulfone nanocomposite: an application of a mixed matrix membrane as a solid-phase microextraction fiber.

A monolithic solid phase microextraction (M-SPME) fiber based on mixed matrix membrane (MMM) is described for the microextraction of phenol, 2-chlorophenol (2CP), 4-nitrophenol (4NP) and 4-methylphenol (4MP) from refinery wastewaters. The sorbent consists of polyethersulfone (PES) and graphitic carbon nitride (g-C3N4), and the phenols were quantified by HPLC with UV detection. This fiber offers good capacity, stability, and ease of preparation and use. The fiber composition, pH value, extraction time, desorption solvent and desorption time were optimized. Under the optimum conditions, the detection limits for the phenolic compounds were in the lower µg L-1 range, and responses were linear in the range from 2 to 2500 µg L-1. Fiber-to-fiber and single-fiber repeatabilities were between 5.2 and 10.4%, and between 4.9 and 8.9%, respectively. The method was applied to the determination of phenolic compounds in wastewater samples and gave recoveries between 72 and 108%. Graphical abstract Schematic epresentation of a monolithic polyethersulfone/graphitic carbon nitride nanocomposite: a novel application of mixed matrix membrane as a solid-phase microextraction fiber.

Application of sunflower stalk-carbon nitride nanosheets as a green sorbent in the solid-phase extraction of polycyclic aromatic hydrocarbons followed by high-performance liquid chromatography.

A green biocomposite of sunflower stalks and graphitic carbon nitride nanosheets has been applied as a solid-phase extraction adsorbent for sample preparation of five polycyclic aromatic hydrocarbons in different solutions using high-performance liquid chromatography with ultraviolet detection. Before the modification, sunflower stalks exhibited relatively low adsorption to the polycyclic aromatic hydrocarbons extraction. The modified sunflower stalks showed increased adsorption to the analytes extraction due to the increase in surface and existence of a π-π interaction between the analytes and graphitic carbon nitride nanosheets on the surface. Under the optimal conditions, the limits of detection and quantification for five polycyclic aromatic hydrocarbons compounds could reach 0.4-32 and 1.2-95 ng/L, respectively. The method accuracy was evaluated using recovery measurements in spiked real samples and good recoveries from 71 to 115% with relative standard deviations of <10% have been achieved. The developed method was successfully applied for polycyclic aromatic hydrocarbons determination in various samples-well water, tap water, soil, vegetable, and barbequed meat (kebab)-with analytes contents ranging from 0.065 to 13.3 µg/L. The prepared green composite as a new sorbent has some advantages including ease of preparation, low cost, and good reusability.