Relative tissue distribution and excretion studies of gastrodin and parishin from powder and extract of Gastrodiae Rhizoma in rat by UHPLC‐ESI‐MS/MS

New research has indicated that Gastrodiae Rhizome (GR) has potential anti‐diabetic and anti‐asthmatic effects in mouse models. On the basis of our previous study of the relative bioavailability of gastrodin (GAS) and parishin (PA) from extract and powder of GR, we performed further research on the tissue distribution and excretion of the two analytes. A reliable bioanalytical method for the quantification of GAS and PA in rat tissues and excretion is required. Chromatographic separation was carried out on a gradient mobile phase of acetonitrile–water with 0.1% formic acid. Calibration curves (1/x ² weighted) offered satisfactory linearity (r ² > 0.9835) within 100–3000 ng mL⁻¹ for GAS and (r ² > 0.9862) within 10–1000 ng mL⁻¹ for PA. The relative standard deviations of the intra‐day and inter‐day precision were all <14.98%, whilst the relative errors of the intra‐day and inter‐day accuracy were all within ±14.71%. The matrix effect and recovery values were satisfactory in all of the biological matrices examination. The data of relative differences in tissue distribution and excretion of GAS and PA from powder and extract of GR indicated that higher bioavailabilities for GAS and PA were obtained when a dosage of 4 g kg⁻¹ GR powder was used.     

An LC–MS/MS method for rapid and sensitive high‐throughput simultaneous determination of various protein kinase inhibitors in human plasma

A reliable, high‐throughput and sensitive LC–MS/MS procedure was developed and validated for the determination of five tyrosine kinase inhibitors in human plasma. Following their extraction from human plasma, samples were eluted on a RP Luna®‐PFP 100 Å column using a mobile phase system composed of acetonitrile and 0.01 m ammonium formate in water (pH ~4.1) with a ratio of (50:50, v /v) flowing at 0.3 mL min⁻¹. The mass spectrometer was operating with electrospray ionization in the positive ion multiple reaction monitoring mode. The proposed methodology resulted in linear calibration plots with correlation coefficients values of r ² = 0.9995–0.9999 from concentration ranges of 2.5–100 ng mL⁻¹ for imatinib, 5.0–100 ng mL⁻¹ for sorafenib, tofacitinib and afatinib, and 1.0–100 ng mL⁻¹ for cabozantinib. The procedure was validated in terms of its specificity, limit of detection (0.32–1.71 ng mL⁻¹), lower limit of quantification (0.97–5.07 ng mL⁻¹), intra‐ and inter assay accuracy (−3.83 to +2.40%) and precision (<3.37%), matrix effect and recovery and stability. Our results demonstrated that the proposed method is highly reliable for routine quantification of the investigated tyrosine kinase inhibitors in human plasma and can be efficiently applied in the rapid and sensitive analysis of their clinical samples.     

Simultaneous Quantitation of Captopril and NSAID's in API,Dosage Formulations and Human Serum by RP‐HPLC

An accurate, sensitive and least time consuming reverse phase high performance liquid chromatographic (RP‐HPLC) method for the estimation of captopril in the presence of non steroidal anti‐inflammatory drugs in formulation and human serum has been developed and validated. Chromatographic separation was conducted on prepacked Purospher star C18 (5 μm, 25 × 0.46 cm) column at room temperature using methanol:water (80:20 v/v) as a mobile phase, pH adjusted at 2.8 with o‐phosphoric acid and at a flow rate of 1.0 mL min⁻¹, while UV detection was performed at 227 nm. The limit of detection and quantification for captopril were 1 and 0.35 ng mL⁻¹, while that for (NSAID's) i.e. flurbiprofen, ibuprofen, diclofenac sodium and mefenamic acid LOD were 0.2, 1, 2 and 0.4 ng mL⁻¹ respectively and LOQ were 0.9, 2.9, 8 and 1 ng mL⁻¹ Analytical recovery was > 98.1%. The method used for the quantitative analysis of commonly administered non steroidal anti‐inflammatory drugs (NSAID's) i.e. ibuprofen, flurbiprofen, diclofenac sodium and mefenamic acid alone or in combination with captopril from API (active pharmaceutical ingredients), dosage formulations and in human serum. The established method is rapid (RT < 12 min), accurate (recovery > 98.1%), selective (no interference of excepients and other commonly used drugs and food) and sensitive (LOQ 3.5 ng mL^;‐1) and reproducible (SD ± 0.003).     

A validated LC‐MS/MS method for the determination of senkyunolide I in dog plasma and its application to a pharmacokinetic and bioavailability studies

Senkyunolide I is one of the major bioactive components in the herbal medicine Ligusticum chuanxiong. The aim of this study was to develop and validate a fast, simple and sensitive LC‐MS/MS method for the determination of senkyunolide I in dog plasma. The plasma samples were processed with acetonitrile and separated on a Waters Acquity UPLC BEH C₁₈ column (50 × 2.1 mm, 1.7 μm). The mobile phase consisted of 0.1% formic acid aqueous and acetonitrile was delivered at a flow rate of 0.3 mL min⁻¹. The detection was achieved in the positive selected reaction monitoring mode with precursor‐to‐product transitions at m/z 225.1 → 161.1 for senkyunolide I and at m/z 349.1 → 305.1 for an internal standard. The assay was linear over the tested concentration range, from 0.5 ng mL⁻¹ to 1000 ng mL⁻¹, with a correlation coefficient >0.9992. The mean extraction recovery from dog plasma was within the range of 85.78–93.25%, while the matrix effect of the analyte was within the range of 98.23–108.89%. The intra‐ and inter‐day precisions (RSD) were <12.12% and the accuracy (RR) ranged from 98.89% to 104.24%. The validated assay was successfully applied to pharmacokinetic and bioavailability studies of senkyunolide I in dogs. The results demonstrated that (a) senkyunolide I showed short elimination half‐life (<1 h) in dog, (b) its oral bioavailability was >40% and (c) senkyunolide I showed dose‐independent pharmacokinetic profiles in dog plasma over the dose range of 1–50 mg kg⁻¹.     

Simultaneous Electrochemical Detection of Co(II) and Cu(II) by 1‐Diazo‐2‐Naphthol‐4‐Sulfonic Acid/MWCNTs Modified Electrode

This work describes a simple preparation of 1‐diazo‐2‐naphthol‐4‐sulfonic acid (1,2,4‐acid) and multiwalled carbon nanotubes (MWCNTs) modified glassy carbon electrode (GCE) for the simultaneous detection of Co(II) and Cu(II). MWCNTs, with their good conductivity and large surface area, were drop‐casted onto the surface of the GCE prior to the electrodeposition of 1,2,4‐acid, a metal chelating agent. Co(II) and Cu(II) were simultaneously measured by differential pulse anodic stripping voltammetry (DPASV) in a batch system. Under optimum conditions, the linear range of Co(II) was between 0.10 and 2.5 μg mL⁻¹ with an LOD of 80 ng mL⁻¹. Two linear ranges were obtained for Cu(II), 0.0050 to 0.030 μg mL⁻¹ and 0.040 to 0.25 μg mL⁻¹,with an LOD of 2.4 ng mL⁻¹. The method offered a high operational stability for up to 52 measurements (RSD=3.4 % for Co(II) and 2.6 % for Cu(II)) and good reproducibility (RSD=1.2 % for Co(II) and 1.7 % for Cu(II)). In the simultaneous detection of Co(II) and Cu(II), there was no effect from common interferences found in wastewater. The method was successfully applied in real water samples with good recoveries (88.2±0.8 to 102.0±0.8 % for Co(II) and 96.5±0.4 to 103.8±0.9 % for Cu(II)) and the results were in good agreement with those obtained from inductively coupled plasma optical emission spectrometry (ICP‐OES) (P >0.05).     

Simultaneous determination and pharmacokinetic study of giraldoid a,giraldoid B in rat plasma after oral administration of Daphne giraldii Nitsche extracts by LC–MS/MS

A simple sensitive LC–MS/MS method has been developed for the simultaneous determination of giraldoid A and giraldoid B in rat plasma. The method was applied to pharmacokinetics studies of the two compounds from Daphne giraldii Nitsche. Chromatographic separation was accomplished on an Acquity UPLC™ BEH C₁₈ column (100 × 2.1 mm, 1.7 mm) by gradient elution with a flow rate of 0.2 mL min⁻¹_. The method was linear over the concentration range of 1.0–1000 ng mL⁻¹, and the lower limits of quantification were 1.04 ± 0.10 and 1.04 ± 0.09 ng mL⁻¹, respectively. The intra‐ and inter‐day precisions (RSD) were <10.14 and 9.96%. The extraction recovery of the analytes was acceptable. Stability studies demonstrated that the two compounds were stable in the preparation and analytical process. The maximum plasma concentration was 687.78 ± 243.62 ng mL⁻¹ for giraldoid A and 952.38 ± 131.99 ng mL⁻¹ for giraldoid B. The time to reach the maximum plasma concentration was 0.50 ± 0.37 h for giraldoid A and 0.50 ± 0.66 h for giraldoid B. The validated method was successfully applied to investigate the concentration–time profiles of giraldoid A and giraldoid B.     

Lansoprazole‐sulfide,pharmacokinetics of this promising anti‐tuberculous agent

Lansoprazole (LPZ) is a commercially available proton‐pump inhibitor whose primary metabolite, lansoprazole sulfide (LPZS) was recently reported to have in vitro and in vivo activity against Mycobacterium tuberculosis . It was also reported that a 300 mg kg⁻¹ oral administration of LPZS was necessary to reach therapeutic levels in the lung, with the equivalent human dose being unrealistic. A validated liquid chromatography–tandem mass spectrometric method (LC–MS/MS) for the simultaneous quantification LPZ and LPZS in rat plasma and lung homogenates was developed. We administered 15 mg kg⁻¹ oral doses of LPZ to a healthy rat model to determine the pharmacokinetics of its active metabolite, LPZS, in plasma and lung tissue. We found that the LPZS was present in amounts that were below the limit of quantification. This prompted us to administer the same dose of LPZS to the experimental animals intraperitoneally (i.p.). Using this approach, we found high concentrations of LPZS in plasma and lung, 7841.1 and 9761.2 ng mL⁻¹, respectively, which were significantly greater than the minimum inhibitory concentration (MIC) for Mycobacterium tuberculosis. While oral and i.p. administration of LPZ resulted in significant concentrations in the lung, it did not undergo sufficient cellular conversion to its anti‐TB metabolite. However, when LPZS itself was administered i.p., significant amounts penetrated the tissue. These results have implications for future in vivo studies exploring the potential of LPZS as an anti‐TB compound.     

Simple determination of betaine,l‐carnitine and choline in human urine using self‐packed column and column‐switching ion chromatography with nonsuppressed conductivity detection

A sequential online extraction, clean‐up and separation system for the determination of betaine, l ‐carnitine and choline in human urine using column‐switching ion chromatography with nonsuppressed conductivity detection was developed in this work. A self‐packed pretreatment column (50 × 4.6 mm, i.d.) was used for the extraction and clean‐up of betaine, l ‐carnitine and choline. The separation was achieved using self‐packed cationic exchange column (150 × 4.6 mm, i.d.), followed by nonsuppressed conductivity detection. Under optimized experimental conditions, the developed method presented good analytical performance, with excellent linearity in the range of 0.60–100 μg mL⁻¹ for betaine, 0.75–100 μg mL⁻¹ for l ‐carnitine and 0.50–100 μg mL⁻¹ for choline, with all correlation coefficients (R²) >0.99 in urine. The limits of detection were 0.15 μg mL⁻¹ for betaine, 0.20 μg mL⁻¹ for l ‐carnitine and 0.09 μg mL⁻¹ for choline. The intra‐ and inter‐day accuracy and precision for all quality controls were within ±10.32 and ±9.05%, respectively. Satisfactory recovery was observed between 92.8 and 102.0%. The validated method was successfully applied to the detection of urinary samples from 10 healthy people. The values detected in human urine using the proposed method showed good agreement with the measurement reported previously.     

Development of a facile and sensitive HPLC‐FLD method via fluorescence labeling for triterpenic acid bioavailability investigation

Triterpenic acids are widely distributed in many fruits and are known for their medicinal benefits. The study of bioavailability has been an important task for a better understanding of the triterpenic acids. Although many methods based on fluorescence labeling for triterpenic acid determination have been established, these reported methods needed anhydrous conditions, which are not suitable for the convenient study of triterpenic acid bioavailability. Inspired by that, a versatile method, which overcomes the difficulty of the reported methods, has been first developed in this study. The novel method using 2‐[12‐benzo[b ]acridin‐5‐ (12H)‐yl]‐acetohydrazide (BAAH) as the fluorescence labeling reagent coupled with high‐performance liquid chromatography with fluorescence detection was first developed for the study of triterpenic acid bioavailability. Furthermore, the labeling conditions have been optimized in order to achieve the best fluorescence labeling yield. Under the optimal conditions, the quantitative linear range of analytes was 2–1000 ng mL⁻¹, and the correlation coefficients were >0.9998. The detection limits for all triterpenic acid derivatives were achieved within the range of 0.28–0.29 ng mL⁻¹. The proposed method was successfully applied to the study of triterpenic acid bioavailability with excellent applicability and good reproducibility.     

Preconcentration and determination of five antidepressants from human milk and urine samples by stir bar filled magnetic ionic liquids using liquid–liquid–liquid microextraction-high-performance liquid chromatography

A sensitive and straightforward liquid–liquid–liquid microextraction method was developed to preconcentrate and cleanup antidepressants, including mirtazapine, venlafaxine, escitalopram, fluoxetine, and fluvoxamine, from biological samples before analyzing with high-performance liquid chromatography. The essential novelty of this study is using magnetic ionic liquids as the extraction phase in the lumen of hollow fiber and preparing a liquid magnetic stir bar. In this method, polypropylene hollow fiber was utilized as the permeable membrane for the analyte extraction. Six magnetic ionic liquids consisting of the transition metal and rare earth compounds were synthesized and then hollow fiber lumen was injected as acceptor phase to extract the antidepressants. Besides, 3-pentanol as a water-immiscible solvent was impregnated in the hollow fiber wall pores. The effective factors in the method were optimized with the central composition design. The resultant calibration curves were linear over the concentration range of 0.8–400.0 ng mL⁻¹ (R² ≥ 0.996). The method displayed the proper detection limit (0.11–0.24 ng mL⁻¹), the reasonable limit of quantification (≤0.79 ng mL⁻¹), wide linear ranges, high preconcentration factors (≥294.3), and suitable relative standard deviation (2.31–5.47%) for measuring antidepressant medications. Analysis of human milk and urine samples showed acceptable recoveries of 96.5–103.8% with excellent relative standard deviations lower than 5.95%.     

Determination of glyphosate and aminomethylphosphonic acid in aqueous soil matrices: A critical analysis of the 9‐fluorenylmethyl chloroformate derivatization reaction and application to adsorption studies

The assessment of the environmental fate of glyphosate and its degradation product (aminomethylphosphonic acid) is of great interest given the widespread use of the herbicide. Studies of adsorption–desorption and transport processes in soils require analytical methods with sensitivity, accuracy, and precision suitable for determining the analytes in aqueous equilibrium solutions of varied complexity. In this work, the effect of factors on the yield of the derivatization of both compounds with 9‐fluorenylmethyl chloroformate for applying in aqueous solutions derived from soils was evaluated through factorial experimental designs. Interference effects coming from background electrolytes and soil matrices were established. The whole method had a linear response up to 640 ng/mL (R² > 0.999) under optimized conditions for high‐performance liquid chromatography with fluorescence detection. Limits of detection were 0.6 and 0.4 ng/mL for glyphosate and aminomethylphosphonic acid, respectively. The relative standard deviation was 4.4% for glyphosate (20 ng/mL) and 5.9% for aminomethylphosphonic acid (10 ng/mL). Adsorption of compounds on four different soils was assessed. Isotherm data fitted well the Freundlich model (R² > 0.97). K_f constants varied between 93 ± 3.1 and 2045 ± 157 for glyphosate and between 99 ± 4.1 and 1517 ± 56 (μg^1‐1/n mL^1/n g^–1) for aminomethylphosphonic acid, showing the broad range of applicability of the proposed method.     

Selective extraction of apixaban from plasma by dispersive solid-phase microextraction using magnetic metal organic framework combined with molecularly imprinted polymer nanocomposite

This research aims to synthesize a specific and efficient sorbent to use in the extraction of apixaban from human plasma samples and its determination by high-performance liquid chromatography-tandem mass spectrometry. High specific surface area of metal-organic framework, magnetic property of iron oxide nanoparticles, selectively of molecular imprinted polymer toward the analyte, and the combination of dispersive solid-phase extraction method with a sensitive analysis system provided an efficient analytical method. In this study, first, a molecularly imprinted polymer combined with magnetic metal organic framework nanocomposite was prepared and then characterized using different techniques. Then the sorbent particles were used for selective extraction of the analyte from plasma samples. The efficiency of the method was improved by optimizing effective parameters. According to the validation results, wide linear range (1.02–200 ng mL⁻¹), acceptable coefficient of determination (0.9938), low limit of detection (0.32 ng mL⁻¹) and limit of quantification (1.02 ng mL⁻¹), high extraction recovery (78%), and good precision (relative standard deviations ≤ 2.9% for intra- (n = 6) and interday (n = 6) precisions) were obtainable using the proposed method. These outcomes showed the high potential of the proposed method for screening apixaban in the human plasma samples.     

A highly efficient and sensitive LC‐MS/MS method for the determination of afatinib in human plasma: application to a metabolic stability study

Afatinib (AFT) is a new tyrosine kinase inhibitor approved for the treatment of nonsmall cell lung cancer. In the present study, a simple, specific, rapid and sensitive liquid chromatography tandem mass‐spectrometric method for the quantification of AFT in human plasma, was developed and validated. Chromatographic separation of the analytes was accomplished on a reversed‐phase Luna^®‐PFP 100 Å column (50 × 2.0 mm; 3.0 μm) maintained at ambient temperature. Isocratic elution was carried out using acetonitrile–water (40:60, v/v) containing 10 mm ammonium formate buffer (pH 4.5) adjusted with formic acid at a flow rate of 0.4 mL min^?1. The analytes were monitored by electrospray ionization in positive ion multiple reaction monitoring mode. The method yields a linear calibration plot (r² = 0.9997) from a quantification range of 0.5–500 ng mL^?1 with the lower limit of quantification and lower limit of detection of 1.29 and 0.42 ng mL^?1, respectively. The intra‐ and inter‐day precision and accuracy were estimated and found to be in the ranges of 1.53–4.11% for precision and ?2.80–0.38% for accuracy. Finally, quantification of afatinib in a metabolic stability study in rat liver microsomes was achieved through the proposed method. Copyright © 2016 John Wiley & Sons, Ltd.     

A simple and rapid HPLC‐UV method for the determination of retigabine in human plasma

A simple and rapid high‐performance liquid chromatographic method with ultraviolet detection was developed for the quantitative determination of retigabine, known also as ezogabine, in human plasma. The assay uses a simple solid‐phase extraction for sample preparation and direct injection of the extract into the chromatograph. Flupirtine is used as an internal standard. Chromatographic separation is achieved on a C₁₈ Chromolith column (Chromolith Performance, 100 × 4.6 mm i.d.), using as mobile phase water/acetonitrile/methanol (72:18:10 v/v/v) mixed with 0.1% of 85% phosphoric acid. Isocratic elution is conducted at a flow rate of 1.5 mL min⁻¹. The total duration of a chromatographic run is 7 min. Calibration curves are linear over the 25–2000 ng mL⁻¹ concentration range, with a limit of quantitation of 25 ng mL⁻¹. Other performance characteristics include high precision (intra‐ and inter‐day coefficients of variation ≤12.6%) and high accuracy (99.7%–108.7%). The method is suitable for the investigation of concentration–response relationships in patients receiving therapeutic doses of retigabine.     

Dithienylmethanone‐Based Cross‐Conjugated Polymer Semiconductors: Synthesis,Characterization, and Application in Field‐Effect Transistors

Herein, we report the synthesis, characterization, and field‐effect properties of two cross‐conjugated dithienylmethanone (DMO)‐based alternating polymers, namely, PDMO‐S and PDMO‐Se . Both polymers possess high thermal stability, good solubility, and broad absorption spectra. Their electrochemical properties were investigated using cyclic voltammetry, indicating that PDMO‐Se has higher HOMO/LUMO energy levels of −5.49/−3.49 eV than −5.57/−3.58 eV of PDMO‐S . The two polymers exhibited promising charge transport properties with the highest hole mobility of 0.12 cm² V⁻¹ s⁻¹ for PDMO‐S and 0.025 cm² V⁻¹ s⁻¹ for PDMO‐Se . AFM and 2D‐GIXRD analyses demonstrated that the PDMO‐S formed lamellar, edge‐on packing thin film with close π‐π stacking. These findings suggest that cross‐conjugated polymers might be potential semiconducting materials for low‐cost and flexible organic electronics. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1012–1019     

Gold(III) Complexes of Asymmetrically Aryl‐Substituted 1,2‐Dithiolene Ligands Featuring Potential‐Controlled Spectroscopic Properties: An Insight into the Electronic Properties of bis(Pyren‐1‐yl‐ethylene‐1,2‐dithiolato)Gold(III)

The electrochemical, UV/Vis–NIR absorption, and emission‐spectroscopic features of (TBA⁺)( 1 ⁻) and the corresponding neutral complex 1 were investigated (TBA⁺=tetrabutylammonium; 1 ⁻=[Au^III(Pyr,H‐edt)₂]⁻; Pyr,H‐edt²⁻=pyren‐1‐yl‐ethylene‐1,2‐dithiolato). The intense electrochromic NIR absorption (λ_max=1432 nm; ε=13000 M ⁻¹ cm⁻¹ in CH₂Cl₂) and the potential‐controlled visible emission in the range 400–500 nm, the energy of which depends on the charge of the complex, were interpreted on the grounds of time‐dependent DFT calculations carried out on the cis and trans isomers of 1 , 1 ⁻, and 1 ²⁻. In addition, to evaluate the nonlinear optical properties of 1 ^x− (x=0, 1), first static hyperpolarizability values β_tot were calculated (β_tot=78×10⁻³⁰ and 212×10⁻³⁰ esu for the cis isomer of 1 ⁻ and 1 , respectively) and compared to those of differently substituted [Au(Ar,H‐edt)₂]^x− gold dithiolenes [Ar=naphth‐2‐yl ( 2 ), phenyl ( 3 ); x=0, 1].     

Inclusion of chlorophenols by 4,4′‐(cyclohexane‐1,1‐diyl)diphenol: structures and kinetics of decomposition

The structures of the inclusion compounds 4,4′‐(cyclohexane‐1,1‐diyl)diphenol–3‐chlorophenol (1/1) and 4,4′‐(cyclohexane‐1,1‐diyl)diphenol–4‐chlorophenol (1/1), both C₁₈H₂₀O₂·C₆H₅ClO, are isostructural with respect to the host molecule and are stabilized by extensive host–host, host–guest and guest–host hydrogen bonding. The packing is characterized by layers of host and guest molecules. The kinetics of thermal decomposition follow the R2 contracting‐area model, kt = [1 − (1 − α)^½], and yield activation energies of 105 (8) and 96 (8) kJ mol⁻¹, respectively.     

Rapid determination of carbendazim in complex matrices by electrospray ionization mass spectrometry with syringe filter needle

The determination of pesticide residues is an indispensable task in controlling food safety and environment protection. Carbendazim is one of the extensive uses of pesticides in the agricultural industry. In this study, a simple method utilizing syringe filter has been applied as electrospray ionization emitter for mass spectrometric identification and quantification of carbendazim in complex matrices including soil, natural water, and fruit juice samples, which contain many insoluble materials. With online syringe filter of the complex samples, most of insoluble materials such as soil were excluded in spray ionization process due to the filter effect, and analytes were subsequently sprayed out from syringe needle for mass spectrometric detection. The pore sizes of filters and diameters of syringe needles also were investigated. The analytical performances, including the linear range (1–200 ng·mL⁻¹), limit of detection (0.2–0.6 ng·mL⁻¹, S/N > 3), limit of quantitation (3.5–8.6 ng·mL⁻¹, S/N > 10), reproducibility (6.4%–12.5%, n = 6), and recoveries (72.1%–91.0%, n = 6) were well acceptable for direct analysis of raw samples. Matrix effect for detection of carbendazim in soil samples also was experimentally investigated. This study demonstrated that syringe filter needle coupled with electrospray ionization mass spectrometry is a simple, efficient, and sensitive method for detection of pesticide residues in water, soil, and fruit juice for risk assessment.     

Riboflavin as a green sorbent in dispersive micro-solid-phase extraction of several pesticides from fruit juices combined with dispersive liquid–liquid microextraction

A vortex-assisted dispersive micro-solid-phase extraction procedure using a new and green sorbent was developed as a simple, fast, and efficient sample preparation method for the extracting five pesticides in several fruit juice samples. In this study, for the first time, riboflavin was used as an efficient sorbent. A few milligrams of riboflavin was directly added into the aqueous solution containing the analytes to adsorb them. After adsorption the analytes, they were desorbed and more concentrated by a dispersive liquid–liquid microextraction procedure. The influence of several effective parameters such as amount of riboflavin, pH, vortex time, eluent nature and volume, and extraction solvent type and volume on the extraction efficiency was investigated. In optimal conditions, linear ranges of the calibration curves were broad. The limits of detection and quantification were attained in the ranges of 0.56–1.5  and 1.9–0.52 ng mL⁻¹, respectively. The proposed method demonstrated to be suitable for concurrent extraction of the studied pesticides in various fruit juice samples with high enrichment factors (320–360) and precision (relative standard deviation ≤7.8% for intra- [n = 6] and interday [n = 4] precisions at a concentration of 25 ng mL⁻¹ of each pesticide).     

A poly (4‐vinylpridine‐co‐ethylene glycol dimethacrylate) monolithic concentrator for in‐line concentration‐capillary electrophoresis analysis of phenols in water samples

A poly(4‐vinylpridine‐co‐ethylene glycol dimethacrylate) monolith was synthesized in a capillary and constructed as a concentrator for the in‐line polymeric monolith microextraction coupling with capillary electrophoresis. The integrated system was then used for the simultaneous determination of five trace phenols (2‐nitrophenol, 3‐nitrophenol, 4‐nitrophenol, 2‐chlorophenol, and 2,4‐dichlorophenol) in water samples. The experimental parameters for in‐line solid‐phase extraction, such as composition and volume of the elution plug, pH of sample solution, and the time for sample loading were optimized. The sensitivity for the mixture of phenols (2‐nitrophenol, 3‐nitrophenol, 4‐nitrophenol, 2‐chlorophenol, and 2,4‐dichlorophenol) enhanced to 615–2222 folds at the optimum condition was compared to the sensitivity for a normal hydrodynamic injection in capillary electrophoresis. Linearity ranged from concentration of 10–500 ng mL^?1(R² > 0.999) for all five phenols with the detection limits of 1.3–3.3 ng mL^?1. In tap, snow and Yangtze River water spiked with 20 ng mL^?1 and 200 ng mL^?1, respectively, the recoveries of 84–105% were obtained. It has been demonstrated that this work has great potential for the analysis of phenols in genuine water samples.