Eluent Solvent Research Articles

Enhancing enrichment ability of Co-Al- layered double hydroxides-mixed matrix membrane microextraction by deep eutectic solvent for analysis of warfarin in biological samples and its quantification via high-performance liquid chromatography-ultraviolet detection

Recent studies on the use of mixed-matrix membrane (MMM) in microextraction methods have considered the use of membrane extraction phase with wide surfaces and high porosity. Here, for the first time, the effect that deep eutectic solvents (DESs) have on the performance of MMM was investigated. The Co-Al-layered double hydroxides mixed matrix membrane (CO-Al-LDH-MMM) was prepared by immobilization of LDH on the pores of the hollow fiber membrane and used as a microextraction device. Deep eutectic solvent via hydrophilic and π-π interactions, aided the dissolution of analyte in the fiber membrane lumen and increases their adsorption onto LDH. Thus, a microextraction method based on the novel LDH-MMM–deep eutectic solvent (LDH-MMM-DES) system was developed and used for the extraction, preconcentration, and quantification of warfarin (as a model analyte) in biological samples. The principal variables that affective influence microextraction efficiency, including the extraction time, type of DES, stirring rate, desorption time, type of eluent solvent, and pH of the sample solution, were screened via Plackett-Burman design and then variables effective optimized by Box-Behnken design. Under the optimum conditions obtained, the developed method showed a good working range (R2 ≥ 0.9951). The limit of detection (LOD) and the limit of quantification (LOQ) ranged from 0.03 μg L−1 (water) to 0.30 μg L−1 (human plasma sample) and from 0.099 μg L−1 (water) to 0.999 μg L−1 (human plasma sample) variables, respectively. The intraday precision was in the range of 2.5–5.6. In order to experiment with the precision and applicability of the Co-Al LDH-MMM DES method, spiking recovery studies were performed in biological samples (urine and humane plasma samples). The recovery results for urine and plasma samples were calculated as 90–91% and 88–93 %, respectively. The results confirmed that the presented method would be promising for the analysis of warfarin in biological samples.

An improved method for the purification and structural analysis of rubropunctatin from red yeast glutinous rice

An improved method for the separation and purification of rubropunctatin from red yeast glutinous rice was developed. In this method, silica gel column chromatography and thin layer chromatography were used to separate the Monascus pigments. Pure methanol and a mixture of ethyl acetate and methanol (13:7, v/v) were selected as the eluent and running solvent, respectively. When compared with previously reported methods, the developed method required fewer types of solvents, and could be suitable for large-scale laboratory production. The extracted pigment was analysed by ultra-high performance liquid chromatography quadrupole time of flight mass spectrometry (UPLC-Q-TOF-MS) and nuclear magnetic resonance (NMR) (1H NMR, 13C NMR). Structural analysis revealed a molecular mass of 353.2 m/z [M－H]－, and a structure including an azaphilone body with two side chains. This structure was consistent with that reported for rubropunctatin. Therefore, the improved purification method reported herein could efficiently be used for the extraction of rubropunctatin from red yeast glutinous rice.

Development of magnetic dispersive micro-solid phase extraction based on magnetic adipic acid nanoparticles and deep eutectic solvents for the isolation and pre-concentration of phenolic compounds in fruit juice samples prior to determination by HPLC-UV

In this research, novel magnetic nanoparticles based on ultrasonic-assisted magnetic dispersive micro-solid phase extraction and deep eutectic solvent have been developed for the determination of phenolic compounds (naringenin, hesperetin, gallic acid) in fruit juice samples. For this purpose, for the first time, adipic acid-coated magnetic nanoparticles (AD@Fe3O4) as an efficient sorbent were synthesized and identified. In this study, deep eutectic solvents were prepared with available and less-toxic compounds and used as eluent solvent in the desorption step. These solvents are good options instead of conventional organic solvents to reduce hazardous waste products and improve the adsorption capacity. In addition, the extracted analytes were easily isolated from the media by an external magnet, and no special devices were required for phase separation. The screening of some important parameters on the extraction procedure was examined by fractional factorial design. Then, the central composite design was applied to optimize the effective parameters. The optimum conditions for the developed method were obtained as pH: 3.7, the amount of salt: 5% (w/v), the amount of adsorbent: 2 mg, and extraction time: 2 min. Under the optimal conditions, the proposed method demonstrated excellent linearity in the range of 1.0–500.0 µg L−1 for hesperetin and 5.0–500.0 µg L−1 for naringenin and gallic acid (R2 > 0.997). The extraction recoveries were obtained above 91.0%, and the intra-day and inter-day precision (RSD%) lower than 4.8%. Limit of detections (LODs) were in the range of 0.3–2.0 µg L−1. The results indicated that the suggested method is simple, fast, and eco-friendly. At the end, the new method was effectively applied for the determination of phenolic compounds in fruit juice samples.

Magnetic dispersive solid phase extraction of ZEAralenone using Fe3O4@ hydroxy propyl methyl cellulose nanocomposite from wheat flour samples prior to fluorescence determination: Multivariate optimization by Taguchi design

The contamination of cereals and cereal products with ZEAralenon (ZEA) is a permanent challenge in human health. A new, sensitive, and fast magnetic dispersive micro solid phase extraction (Magnetic D-µ-SPE) was developed for preconcentration and quantitative spectrofluorometric determination of ZEA in wheat flour samples. The Fe3O4@hydroxypropyl methylcellulose (Fe3O4@HPMC) nanocomposite was prepared and used as an efficient magnetic adsorbent. The characterization of the synthesized nanocomposite by the co-precipitation method was confirmed by the FT-IR, TEM, XRD, and VSM analysis. Taguchi L16 array was used for the design of experiments to investigate the influences of extraction parameters on the recovery percentage of µ-SPE. A pH of 4, a magnetic nanoparticle weight of 30 mg, ionic strength of (6 w/v %), extraction time of 3 min, desorption time of 6 min, and 500 µL of MeOH as an efficient eluent solvent were the optimized extraction parameters. Under the optimal working conditions, this method showed good linearity in the range of 8–320 ng g−1 (R2 = 0.9991) with a limit of detection of 6.01 ng g−1. The method recoveries ranged from 83.8 to 111.0 % for wheat flour samples. The results showed that this simple, inexpensive method with low organic solvent consumption was accurate and significantly free from interference effects. The proposed method was successfully applied to determine trace amounts of ZEA from wheat flour sample matrices. This method is rapid with an average extraction time of 9 min and high enrichment (~53 %) and has many advantages such as operational simplicity without using expensive methods such as HPLC or immunoassay column, minimization of solvent utilization, and good accuracy.

Sample preparation optimization by central composite design for multi class determination of 172 emerging contaminants in wastewaters and tap water using liquid chromatography high-resolution mass spectrometry

Multi-residue analysis is highly desirable for water quality control. To this end, a comprehensive workflow for the quantitative analysis of 172 anthropogenic organic compounds belonging to emerging contaminants (pharmaceuticals and personal care products, illicit drugs, organophosphate flame retardants and perfluoroalkyl substances) has been developed for application to wastewater and tap water, based on solid phase extraction (SPE) and Orbitrap high resolution mass spectrometry (HRMS). Due to the large number of analytes with various physicochemical characteristics that should be efficiently extracted, the response surface methodology (RSM) employing a central composite design (CCD) and desirability function (DF) approach was exploited to optimize the sample preparation process, instead of the conventional single-factor analysis. The factors included in the design of experiments (DoE) were sample pH, eluent solvents composition and volume. Statistical analysis (ANOVA) proved the adequacy of the proposed model (2- factor interaction) as p-value < 0.05 followed by different diagnostic tests confirmed the good fitting. The best values to acquire DF close to 1 were pH 3.5, methanol/ethyl acetate ratio 87:13 and eluent volume 6 mL. The streamlined method was validated in terms of accuracy, linearity, method limits, reproducibility, and matrix effect. The proposed workflow combines sensitivity and robustness, with recoveries over 70%, method quantification limits <1 ng/L, and relative standard deviations <20% for most of the compounds. Slight matrix effect (ME) was observed for most of PPCPs, IDs and PFAs, in contrast with most of the OPFRs, for which strong ME was calculated. Method applicability was tested over wastewater collected from a municipal wastewater treatment plant in Thessaloniki (Greece), revealing the presence of 69 and 40 compounds in influents and effluents, respectively, at varying concentrations.

Synthesis and characterisation of MCM-41@SiO2-NH-pydc as a new nano mesoporous sorbent: application for the simultaneous preconcentration of cationic dyes previous spectrophotometric determination, using taguchi experimental design

ABSTRACT In this study, a new nano mesoporous MCM-41@SiO2-NH-pydc was successfully synthesised and was used as a new and low-cost adsorbent for the simultaneous influential clean-up, preconcentration and determination of crystal violet (CV) and auramine O (AO) dyes. The as-synthesised sorbent was characterised by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX), thermogravimetric (TGA) and derivative thermogravimetric (DTG) and Brunauer–Emmett–Teller (BET) techniques. The extraction performance was evaluated by dispersive solid phase micro extraction (DSPME) of CV and AO from real samples. The analysis was carried out by UV-Vis spectrophotometric. The analytical results confirmed that theMCM-41@SiO2-NH-pyd could be an appropriate candidate as asorbent forDSPME. The maximum recoveries (95.95% and 92.95% for CV and AO, respectively) was obtained at 0.015 g MCM-41@SiO2-NH-pydc sorbent, pH = 8.0, 500 μL DMF as eluent solvent, 20 and 10 min extraction and centrifuge time, respectively, and 50 second desorption time. After the optimum conditions, the limit of detection (LOD), quantification (LOQ) and linear range were obtained, 0.0010, 0.0033 and 0.008–0.6 mg L−1 for CV and 0.0056, 0.0187 and 0.03–1.5 mg L−1for AO, respectively. The relative standard deviations (RSD) for five analyses were 4.2% for CV and 4.6% for AO. In comprising with the previous reported methods, the developed method provided a relatively in expensive, time-saving and environmentally friendly advantages. The developed analytical method can be applied for the determination of CV and AO with sufficient sensitivity as well as acceptable reproducibility.

Triazine-triphenylphosphine based porous organic polymer as sorbent for solid phase extraction of nitroimidazoles from honey and water

A triazine-based porous organic polymer was prepared by facile solvothermal polymerization with cyanuric chloride and triphenyl phosphine as functional monomers. The polymer was characterized and then used for the first time as the sorbent for the effective solid-phase extraction of some nitroimidazoles (NDZs) (metronidazole, ronidazole, secnidazole, dimetridazole and ornidazole). The main experimental influencing parameters for the extraction including the eluent solvent, eluent volume, sample loading rate, sample solution pH, salt concentration and sample volume were investigated. The adsorption kinetics and adsorption isotherms were investigated to elucidate the possible adsorption mechanism. With the triazine-based porous organic polymer as the SPE adsorbent, trace NDZs were effectively extracted. The good enrichment capability for the NDZs was mainly attributed to the hydrogen binding interactions by the aromatic 1,3,5-trizine rings. After the SPE, the extracted analytes were analyzed by high-performance liquid chromatograph with ultraviolet detection. Under the selected conditions, the method had a good linear response for the analytes in the range of 0.06-120 ng mL−1 for water and 1.5-1200 ng g−1 for honey samples. The limits of detections (S/N=3) fell in the range of 0.02-0.06 ng mL−1 for water and 0.5-1.5 ng g−1 for honey samples. The method recoveries for the analytes for spiked samples were in the range of 80.3-118%. The method can be applied for the determination of the NDZs from real samples.

RAFT Method for Preparation of Molecularly Imprinted Polymer–SBA15 Nanocomposite as a Pipette Tip Solid-Phase Microextraction Adsorbent

Methoxyfenozide-selective surface molecularly imprinted polymer (MIP) sorbent was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization based on support matrix of SBA-15. The size, morphology, composition, and properties of the prepared nanocomposite have also been characterized and determined using scanning electron microscopy (SEM) and Fourier-transform- infrared (FT-IR) spectroscopy. A miniaturized solid-phase extraction procedure has been developed for ultra-trace determination of methoxyfenozide adsorbed on polymethacrylic acid-functionalized Santa Barbara Amorphous type material (SBA-15), which is packed into a pipette- tip (PT). The PT-SPE was assembled by packing 2.0 mg of nanocomposite of MIP as sorbent into a 100 μL pipette tip. The method was optimized for several important extraction parameters such as sample volume, pH, amount of sorbent, and eluent solvent. The results determine that the prepared adsorbent has a high extraction power. High sensitivity, non-use of organic solvent, high selectivity, and low detection limits are the unique advantages of the proposed method.

Surface molecular design of organic–inorganic mesoporous hybrid materials for CO2 capture

In the present work, a series of organic–inorganic hybrids was designed by using different solvents on 3-aminopropyltriethoxysilane (APTS) grafting on SBA-15. Different characterization techniques were used to evaluate how distinct solvents drive the surface architecture, amine loading, APTS-SBA-15 linkage configuration, surface area and pore volume. FT-IR and 29Si MAS NMR confirmed APTS grafting on SBA-15 surface. Elemental analysis showed that N loading varied from 2.09% up to 5.21%, while the range of C/N ratios (2.69–4.34) indicated that the number of bonds formed between APTS and SBA-15 (linkage configuration) remained between 2 (C/N = 4.3) and 3 (C/N = 2.6). N2 physisorption and TGA data showed that textural properties and APTS content on the synthesized materials were simultaneously dependent on N loading and linkage configuration. The presented data showed that the hybrids properties can be correlated with the solvent polarity, more specifically with the interaction between the inorganic matrix surface and the solvent during grafting. A new approach was presented using the solvent eluent strength to rationalize such correlation. Among all tested solvents, cyclohexane rendered the adsorbent with the highest N loading (5.21%) and more stable linkage configuration (C/N = 4.34). CO2 capture tests showed that the increase of amine loading and surface density improves not only the hybrid capacity to chemisorb CO2, but also its adsorption efficiency. CO2 capture capacities varied from 25 up to 516 µmol CO2 g−1. The correlation between adsorption capacity and N content for the synthesized APTS-SBA-15 hybrids was best fitted by a power function.

Simultaneous determination of four opioids in urine by solid-phase extraction and derivatization coupled with gas chromatography-mass spectrometry

Police officers currently use the colloidal gold rapid testing method to detect heroin in the urine of drug abusers, but the results are often rendered erroneous due to the presence of antitussive drugs, which contain opioids. The traditional manual liquid-liquid extraction method for urine testing has low efficiency and poor sensitivity, and hence, it fails to meet the requirements of the public security department to crack down on drug abusers. Therefore, to avoid punishment, most rapid-test-positive people make false claims about intaking cough suppressants. It is imperative to establish a highly efficient automatic method for the simultaneous determination of multiple opioids in urine, to rule out the use of heroin. A method based on solid-phase extraction and derivatization coupled with gas chromatography-mass spectrometry (GC-MS) has been developed for the simultaneous detection of morphine, O6-acetylmorphine, codeine, and acetyl codeine in urine. Since these four opioids exists as cations in acidic aqueous solution, the urine samples collected from dead bodies or drug addicts were adjusted to pH 6 by using phosphate buffer, enriched, and purified by MCX-SPE columns. Then, morphine, O6-acetylmorphine, and codeine were derivatized by N-methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA) for GC-MS testing. The effects of sample loading and elution flow rate, percentage of formic acid in the wash solvent (methanol), percentage of ammonia in the eluent (methanol), volume of the wash solvent, and drying time of the cartridge on the extraction efficiency were investigated in detail. The best results were obtained under the following conditions:sample loading and elution flow rate, 1.0 mL/min; volume fraction of formic acid in the wash solvent, 3%; volume fraction of ammonia in the eluent solvent, 5%; volume of 3% (v/v) formic acid in methanol (eluent), 1 mL; and drying time of the cartridge, 1 min. The GC-MS results showed good linearity in the range of 0.02-0.8 μg/mL with correlation coefficients (r2) ≥ 0.998. The limits of detection (LODs) and limits of quantification (LOQs) were 0.0016-0.0039 μg/mL and 0.0054-0.0128 μg/mL, respectively. The recoveries of the target analytes were between 93.0% and 110.3% at spiked levels of 0.02, 0.1, and 0.2 μg/mL. As opposed to similar reported methods, our method showed high sensitivity and recovery; furthermore, the matrix interference was eliminated, and the chromatographic peaks of the analytes were completely separated from the impurity peaks at the level of 0.2 μg/mL. The automatic solid-phase extraction equipment is convenient to operate and allows one to process samples in batches. The conditions for solid-phase extraction can be precisely controlled, and the detection accuracy is greatly improved. In addition, a large number of sample tests can be performed by a few experimenters. Hence, this method facilitates simple and rapid forensic toxicology testing and drug abuse monitoring on a large scale.

Larvicidal potential of different chromatographic fractions of the n-hexane extract of Artemisia scoparia against the vector mosquito Culex quinquefasciatus

The present study aims to explore the larvicidal activity of n-hexane extract isolated fractions from Artemisia scoparia against third instar larvae of Culex quinquefasciatus mosquito. Twelve fractions, F1 to F12 were separated through column chromatography by using different eluent solvents such as hexane, hexane-chloroform, chloroform and chloroform-methanol, in the order of increasing polarity. Larval bioassay was done by using WHO standard guideline. Larvicidal potential of the separated fractions was evaluated at tested concentrations of 30, 60, 90 and 120 ppm. Mortality rate was scored 24 h post exposure. The fractions F3 and F4 were found more active, exhibiting LC50 values of 28.66 and 22.37 ppm and LC90 values of 53.59 and 53.16 ppm respectively. The larvicidal activity of different fractions was compared by using ANOVA analysis.

Combination of magnetic solid‐phase extraction with dispersive liquid–liquid microextraction followed by GC‐MS for trace analysis of synthetic cannabinoids in plasma samples

In this work, an efficient extraction method based on a combination of magnetic solid-phase extraction (MSPE) and dispersive liquid–liquid microextraction (DLLME) followed by GC-MS was developed for the determination of 5F-ADB-PINACA (ADB) and AB-FUBINACA (AB). Fe3O4 nanoparticles coated with poly ortho-aminophenol were synthesised and applied as the sorbent. Extraction parameters including pH in both the MSPE (pH 3.5) and DLLME (pH 11) steps, sorbent amount (20 mg), salt effect (10%, w/v), adsorption (20 min) and desorption time (5 min), type and volume of eluent (1.0 ml of acetone) and extraction solvent (25 µl of toluene), were optimised. Enrichment factors of 213 and 437 obtained for ADB and AB, respectively. The linear ranges of the method were obtained 0.2–50 and 0.2–50 ng ml−1 for ADB and AB, respectively. Regression coefficients above 0.998 and LODs of 0.01 and 0.005 ng ml−1 resulted. The intra- and inter-day RSDs% (n = 3) were found to be 8.3 and 7.6%, respectively. Finally, MSPE-DLLME-GC/MS was applied for the determination of analytes in plasma samples. Recoveries were within the range of 87.6–102.6 and 89.4–104% for the ADB and AB, respectively, indicating the suitability of the proposed method for analysis of ADB and AB in complicated matrices.

Co-Fe-layered double hydroxide decorated amino-functionalized zirconium terephthalate metal-organic framework for removal of organic dyes from water samples.

In this study, a new efficient adsorbent of Co-Fe-layered double hydroxides@metal-organic framework (Co-Fe-LDH@UiO-66-NH2) was synthesized and used for extraction of methylene blue (MB) and methylene red (MR) from water samples prior to their determination by UV-Vis spectrophotometer. The adsorbent was characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray (EDX), X-ray Diffraction (XRD), and Brunauer-Emmett-Teller (BET) analyses. The impact of various parameters such as pH of the aqueous phase, extraction time, amount of adsorbent, type and volume of eluent solvent, desorption time, and sample volume were studied. The maximum extraction recovery was obtained at an optimized pH8.0 and extraction time 10.0min. The adsorption process was fitted by the Langmuir model with a maximum adsorption capacity of 555.62mg/g and 588.2mg/g, respectively, for MB and MR. Under optimum conditions, the limit of detection (LOD) for MB was 0.7 μgL-1 and 0.9 μgL-1 for MR. Furthermore, the Co-Fe-LDH@UiO-66-NH2 composite showed high efficiency for the removal of the analytes from environmental water samples.

Application of Cu-based metal-organic framework (Cu-BDC) as a sorbent for dispersive solid-phase extraction of gallic acid from orange juice samples using HPLC-UV method

In the current work, the Cu-based metal-organic framework (MOF) (Cu-BDC) was synthesized through a simple and one-pot solvothermal method and used as a sorbent for dispersive solid-phase extraction (DSPE) of gallic acid (GA) from orange juice samples followed by high-performance liquid chromatography-ultraviolet (HPLC-UV) determination. The prepared Cu-BDC was fully characterized using different analysis including Fourier-transform infrared spectroscopy (FT-IR), X-ray Powder Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS) and Brunauer-Emmett-Teller (BET). The prepared Cu-BDC had exceptional properties in terms of high specific surface area (400 m2 g−1) and high adsorption capacity (300 mg g−1) toward GA. The influence of effective factors on extraction recovery of GA such as sorbent dosage, ultrasonic time, washing solvent volume and eluent solvent volume was evaluated using a central composite design (CCD) based response surface methodology (RSM). Under the optimized conditions, the presented method showed a wide linear range of 0.5–15.0 mg L−1 with a detection limit of (0.145 mg L−1) and acceptable repeatability (RSD < 6.0%) which shows the applicability of the proposed method for accurate determination of GA from complicated orange juice samples.

Simultaneous Removal of Heavy Metals from Wastewater Using Modified Sodium Montmorillonite Nanoclay.

Sodium montmorillonite nanoclay particles were modified by 3-aminopropyltrimetoxysilane using a physical vapor deposition method and applied for the simultaneous removal of Cd, Zn, Pb and Ni heavy metals from wastewater samples. Experiments were performed in both batch and column systems. Several parameters that influence the removal efficiency, such as the pH, contact time, amount of adsorbent, interfering ions, flow rate of sample passage and eluent solvent, were evaluated and optimized. The results showed that the adsorption isotherms obeyed Langmuir isotherms for all heavy metals. Also, interfering ions did not influenced the removal efficiency. Finally, modified nanoclay successfully could remove all heavy metals from real wastewater samples to near completeness.

Magnetic metal organic framework for pre-concentration of ampicillin from cow milk samples

The aim of this study is a present of a simple solvothermal synthesis approach to preparation of Cu-based magnetic metal organic framework (MMOF) and subsequently its application as sorbent for ultrasound assisted magnetic solid phase extraction (UAMSPE) of ampicillin (AMP) from cow milk samples prior to high performance liquid chromatography-Ultraviolet (HPLC-UV) determination. Characteristics of prepared MMOF were fully investigated by different techniques which showed the exclusive properties of proposed sorbent in terms of proper functionality, desirable magnetic property and also high specific surface area. Different influential factors on extraction recovery including sorbent dosage, ultrasonic time, washing solvent volume and eluent solvent volume were assessed using central composite design (CCD) based response surface methodology (RSM) as an operative and powerful optimization tool. This is the first report for determination of AMP using MMOF. The proposed method addressed some drawbacks of other methods and sorbents for determination of AMP. The presented method decreases the extraction time (4 min) and also enhances adsorption capacity (250 mg/g). Moreover, the magnetic property of presented sorbent (15 emu/g) accelerates the extraction process which does not need filtration, centrifuge and precipitation procedures. Under the optimized conditions, the proposed method is applicable for linear range of 1.0–5000.0 μg/L with detection limit of 0.29 μg/L, satisfactory recoveries (≥95.0%) and acceptable repeatability (RSD less than 4.0%). The present study indicates highly promising perspectives of MMOF for highly effective analysis of AMP in complicated matrices.

Determination of four bisphenols in water and urine samples by magnetic dispersive solid‐phase extraction using a modified zeolite/iron oxide composite prior to liquid chromatography diode array detection

A novel approach is presented to determine four bisphenols in water and urine samples, employing magnetic dispersive solid-phase extraction combined with liquid chromatography and diode array detection. A modified zeolite-based magnetic composite was used as an efficient sorbent, combining the advantages of magnetic materials with the remarkable properties of zeolites. A multivariate optimization design was employed to optimize some experimental factors affecting magnetic dispersive solid-phase extraction. The method was evaluated under optimized conditions (i.e., amount of sorbent, 50mg; sample pH, unadjusted; NaCl concentration, 1.25%; extraction and elution time, 2min; eluent solvent, ethanol; eluent solvent volume, 400µL), obtaining good linearity with correlation coefficients ranging between 0.995 and 0.999 (N=5) (from 2 to 250µg/L for bisphenol A, bisphenol AP, and bisphenol P and from 5 to 250µg/L for bisphenol AF). Method repeatability was assessed obtaining coefficients of variation between 3 and 11% (n=6). Finally, the method was applied to spiked real samples, obtaining for water samples relative recoveries between 83 and 105%, and for urine samples between 81 and 108% for bisphenol A, bisphenol AP, and bisphenol AF, and between 47 and 59% for bisphenol P.

Zirconium metal-organic framework assisted miniaturized solid phase extraction of phenylurea herbicides in natural products by ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry

The zirconium metal-organic framework (Zr-MOF) was used as a novel and effective adsorbent material for the enrichment of five phenylurea herbicides (fenuron, monuron, diuron, linuron and pencycuron) in natural products. The target analytes were determined by ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. Some crucial experimental parameters, such as type of adsorbents, amount of adsorbent, type of eluent solvents and adsorption capacity were investigated and optimized. Under the optimum extraction conditions, the enrichment factors of fenuron, monuron, diuron, linuron and pencycuron were 90, 128, 148, 204 and 295 times, respectively. A good linearity was obtained in different concentration levels of target analytes with the determination coefficients (r2) larger than 0.993. In addition, the limits of detection varied from 0.05 to 0.36 ng/mL and the recoveries of the analytes were in the range of 85.19–99.13 %. The results demonstrated that the proposed miniaturized solid-phase extraction procedure coupled with Zr-MOF could become an effective tool to analyze phenylurea herbicides and would have the vast application prospect for the extraction of pesticide residue and more organic pollutants from Hawthorn, Dendrobii Officinalis Caulis and Salviae Miltiorrhizae Radix et Rhizoma samples.

Polythiophene as highly efficient sorbent for microextraction in packed sorbent for determination of steroids from bovine milk samples

Herein, a method based on microextraction in packed sorbent (MEPS) with polythiophene (PTh) as adsorbent material and HPLC-DAD was developed. PTh was synthesized by oxidative method and used to extract progesterone (PGN), prednisolone (PRE) and estradiol (ESD) from bovine milk samples. The adjusted chromatographic conditions were: C18 column (150 mm × 4.60 mm, 5 µm), mobile phase: methanol: acetonitrile (55: 45, v/v) with flow rate at 0.85 mL min−1 and temperature at 40 °C. The main parameters that affecting the sample preparation were optimized: washing solvent, eluent solvent, sample pH, volume sample, mass of sorbent, and cycles of aspersion/dispersion. The method presented linearity in the linear range between 16 and 1200 ng mL−1 and correlation coefficients (r) ≥ 0.99 for the three analytes with recoveries greater than 85%. The validated method was used successfully for the analyses of bovine milk samples.

Separation and determination of ciprofloxacin in seawater, human blood plasma and tablet samples using molecularly imprinted polymer pipette-tip solid phase extraction and its optimization by response surface methodology.

By synthesizing a molecular imprinted polymer as an efficient adsorbent, ciprofloxacin was micro-extracted from seawater, human blood plasma and tablet samples by pipette-tip micro solid phase extraction and determined spectrophotometrically. Response surface methodology was applied with central composite design to build a model based on factors affecting on microextraction of ciprofloxacin; including volume of eluent solvent, number of extraction cycles, number of elution cycles, and pH of sample. Other factors that affect extraction efficiency, such as type of eluent solvent, volume of sample, type, and amount of salt were optimized with one-variable-at-a-time method. Under optimum extraction condition, pH of sample solution was 7.0, volume of eluent solvent (methanol) was 200µL, volume of sample solution was 10mL, and the number of extraction and elution cycles was five and seven, respectively, amount of Na2 SO4 (as salt) and MIP (as sorbent) were optimized at 150 and 2mg, respectively. The linear range of the suggested method under optimum extraction factors was 5-150µg/L with a limit of detection of 1.50µg/L for the analyte. Reproducibility of the method (as relative standard deviation) was better than 7%.