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Molecularly imprinted polymers prepared by Pickering emulsion method with lignin as stable particle were used as dispersants in matrix solid‐phase dispersion, followed by ultra high performance liquid chromatography with tandem mass spectrometry to research the degradation behavior of matrine in soil. The molecularly imprinted polymers have regular morphology and uniform particles. Moreover, the adsorption experiments and the conditions of matrix solid‐phase dispersion were discussed. With the optimal conditions of matrix solid‐phase dispersion, the recoveries of matrine were 95.4–98.2%, relative standard deviations were 0.6–5.1%, and the detection limit was 5 ng/g. Moreover, the degradation behavior of matrine in soil was researched, it indicated the half‐life of matrine was 2.7–3.2 days, and it was an environmentally friendly botanical pesticide. The method was successfully applied to separate and analyze matrine in soil samples can decrease analysis time, save organic solvents, and improve the selectivity. [ABSTRACT FROM AUTHOR]

The authors describe an efficient method for the extraction of tetracycline antibiotics (TCs) from water samples by using a new kind of core-shell adsorbent. It consists of a magnetite (FeO) core and a metal-organic framework (type ZIF-8) as the shell. The sorbent has a large specific surface and superparamagnetic response. The sorbent was characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, nitrogen adsorption, and X-ray diffraction. The adsorption isotherms, dynamic adsorption, and mechanisms of interactions between tetracycline and sorbent were studied. Various parameters affecting the extraction efficiency were optimized. Following desorption of the TCs with methanol (containing 1% of acetic acid), they were quantified by using ultra-high performance liquid chromatography combined with mass spectrometry. The method has a linear range that extends from 0.5 to 50 ng·L, and the limits of detection for tetracycline, chlortetracycline, and oxytetracycline are 0.125, 0.122 and 0.143 ng·L, respectively. The relative standard deviations of intra-day and inter-day assays range from 3.3% to 8.5%, and from 2.8% to 8.3%, respectively. The recoveries of TCs (at spiking levels of 0.5, 5.0 and 50 ng·L) are in the range between 78.3% and 93.7%. The method was successfully applied to the determination of TCs in spiked river water, fish pond water, and livestock wastewater. [ABSTRACT FROM AUTHOR]

A simple method based on matrix solid phase dispersion (MSPD) using molecularly imprinted polymers (MIPs) as sorbents for selective extraction of malachite green (MG) from aquatic products was developed. The MIPs were prepared by using carbon nanotube as support, MG as template, methacrylic acid as functional monomer, ethyleneglycol dimethacrylate as crosslinker and methylene chloride as solvent. The MIPs were characterized by Fourier transform infrared spectrometry and transmission electron microscopy. The isothermal adsorption, kinetics absorption and selective adsorption experiments were carried out. We optimized the extraction conditions as follows: the ratio of MIPs to sample was 2:3, the dispersion time was 15 min, washing solvent was 4 mL 50% aqueous methanol and elution solvent was 3 mL methanol-acetic acid (98: 2, v/v). Once the MSPD process was completed, the MG extracted from aquatic products was determined by high performance liquid chromatography. The detection limit of MG was 0.7 μg kg −1 . The relative standard deviations of intra-day and inter-day were obtained in the range of 0.9%–4.7% and 3.4%–9.8%, respectively. In order to evaluate the applicability and reliability of the proposed method, it was applied to determine MG in different aquatic products samples including fish, shrimp, squid and crabs. The satisfied recoveries were in the range of 89.2%–104.6%. The results showed that this method is faster, simpler and makes extraction and purification in the same system. [ABSTRACT FROM AUTHOR]

Magnetic molecularly imprinted polymers based on carbon nanotubes were prepared and characterized by infrared spectrometry, transmission electron microscopy, and vibrating sample magnetometry and were employed for the isolation of acephate from cabbage, spinach, lettuce, leeks, and celery. Kinetic and recognition studies were carried out in order to investigate the adsorption properties of the polymers. During the application process, the acephate extracted from vegetables was purified with the magnetic molecularly imprinted polymers and determined by high performance liquid chromatography with an ultraviolet detector. The recoveries of acephate at three fortified concentrations (0.015, 0.15, and 1.5 mg kg−1) were between 89.2% and 93.4%. The limits of detection and quantification of acephate were 0.0025 and 0.0077 mg kg−1, respectively. The linear dynamic range was from 0.01 to 5 mg kg−1. The relative standard deviations of intra- and inter-day precision were 1.1% to 5.9% and 2.7% to 6.4%, respectively. The developed method was demonstrated to be rapid and selective for the extraction and determination of acephate in vegetables. [ABSTRACT FROM PUBLISHER]

Highlights: [•] MMIPs were prepared based on CNTs. [•] MMIPs were used for extraction of pyrethroids from fruit samples. [•] The isothermal adsorption and dynamics adsorption were studied. [•] The selectivity of MMIPs was investigated. [•] The proposed method is fast, simple and selective. [ABSTRACT FROM AUTHOR]

A simple method based on matrix solid-phase dispersion for selective extraction of anthraquinones from rhubarb samples was developed using a molecularly imprinted polymer as sorbent. The molecularly imprinted polymer was prepared using emodin as the template molecule, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross-linking agent. The polymer was characterized by scanning electron microscopy and Fourier-transform infrared spectrometry. Isothermal adsorption and dynamic adsorption experiments were performed. The best extraction conditions for anthraquinones were obtained at a ratio of molecularly imprinted polymer to sample of 1:1, a dispersion time of 5 minutes, with 5% aqueous methanol as the washing solvent, and an elution solvent of methanol-acetic acid (99:1,v/v). Once the matrix solid-phase dispersion process was optimized, the extract was reacted with 8% hydrochloric acid for hydrolysis. The anthraquinones extracted from rhubarb were determined by liquid chromatography. The detection limits of chrysophanol, emodin, physcion, and aloe-emodin were 0.23, 0.24, 0.28, and 0.27 µg mL−1, respectively. The proposed method was compared with the method in Chinese pharmacopoeia, and the results show that the extraction yield of anthraquinones obtained by molecularly imprinted polymer–matrix solid-phase dispersion method was higher. Moreover, the proposed method is faster and simpler and can achieve extraction and purification in the same system. [ABSTRACT FROM AUTHOR]

We report on a method for the extraction of organophosphorus pesticides (OPPs) from water samples using mixed hemimicelles and magnetic titanium dioxide nanoparticles (FeO@TiO) modified by cetyltrimethylammonium. FeO@TiO nanoparticles were synthesized by a hydrothermal process and then characterized by scanning electron microscopy and Fourier transform IR spectrometry. The effects of the quantity of surfactant, extraction time, desorption solvent, pH value, extraction volume and reuse of the sorbent were optimized with respect to the extraction of OPPs including chlorpyrifos, dimethoate, and trichlorfon. The extraction method was applied to analyze OPPs in environmental water using HPLC along with UV detection. The method has a wide linear range (100-15,000 ng L), good linearity ( r > 0.999), and low detection limits (26-30 ng L). The enrichment factor is ~1,000. The recoveries (at spiked levels of 100, 1,000 and 10,000 ng L) are in the range of 88.5-96.7 %, and the relative standard deviations range from 2.4 % to 8.7 %. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The magnetic chitosan was prepared by adding chitosan, Fe2+and Fe3+into a basic precipitant of NaOH solution. The synthetic magnetic chitosan was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and physical properties. The adsorption characteristics of magnetic chitosan for extracting pyrethroids from water samples were investigated. The analytes were separated by magnetic solid phase extraction and determined by high performance liquid chromatography. The optimum conditions of adsorption experiments were obtained: the amount of sorbent was 80 mg, the extraction time was 20 min, the washing solvent was 50% aqueous methanol, and the eluent was acetonitrile-acetic acid (99: 1,v/v). The obtained linearity of three pyrethroids was in the range of 30–3000 ng L−1. The detection limits of beta-cyfluthrin, cyhalothrin, and cyphenothrin were 7.5, 5.6, and 6.1 ng L−1, respectively. The intra-day and inter-day precisions of three pyrethroids were in the range of 3.6–5.2% and 5.9–8.6%, respectively. In the optimized conditions, three water samples were analyzed, and the recoveries of pyrethroids obtained were 83.2–95.2%. [ABSTRACT FROM AUTHOR]

Abstract: A simple method based on magnetic molecularly imprinted polymers (MMIPs) for the separation of Sudan dyes from chilli powder samples has been developed. The MMIPs were synthesized as follows: the Fe3O4 nanoparticles were encapsulated with a SiO2 shell and functionalized with ph name="dbnd" />CH2, then the polymers were further fabricated by surface-imprinted polymerization using Sudan IV as template molecule, methacrylic acid as functional monomer, and ethylene glycol dimethacrylate as cross-linking agent. The prepared MMIPs were characterized by scanning electron microscope, Fourier transform infrared spectrometry and physical property measurement system. The isothermal absorption experiment, kinetics absorption experiment and selectivity of MMIPs were tested. The analytes were determined by high performance liquid chromatography. Under the optimal conditions, the limits of detection of the four Sudan dyes are 6.2, 1.6, 4.3 and 4.5ngg−1, respectively. The precision expressed as relative standard deviation ranging from 4.8% to 9.1% was obtained. In all three fortified levels (25, 250 and 2500ngg−1), recoveries of Sudan dyes were in the range of 79.9–87.8%. [Copyright &y& Elsevier]

Abstract: A rapid method based on dynamic microwave-assisted extraction (DMAE) coupled on-line with clean-up was developed for the determination of caffeine in tea samples. A TM010 microwave resonance cavity was applied to concentrate the microwave energy. An extraction vessel was placed in microwave irradiation zone of the TM010 microwave resonance cavity. A silica gel column connected with the extraction vessel was used to remove chlorophyll in tea. The extraction and clean-up procedures were carried out simultaneously in a single step. The DMAE parameters were optimized by the Box–Behnken design. The maximum extraction efficiency was achieved using 70 W of microwave power, 3.5 mL of extraction solvent and 1.0 mL min−1 of extraction solvent flow rate. The limit of detection obtained is 0.012 mg g−1. The RSDs of intra- and inter-day of eight kinds of tea samples are 2.7%–5.4% and 5.1%–7.3%, respectively. The recovery of caffeine in the tea samples is in the range of 88.2%–99.3%.The proposed method has selectivity and sensitivity and considerably less labor and time for determination of caffeine in tea compared with conventional extraction methods, such assoxhlet extractionand liquid–liquid extraction. [Copyright &y& Elsevier]

Abstract: A green and simple method was developed for determination of sulfonamides (SAs) in soil samples. The procedure was based on the microwave-assisted extraction (MAE) of SAs from soil using non-ionic surfactant Triton X-114 as the extraction medium. Then sodium chloride was added into the MAE extract and the mixture was equilibrated for some time at high temperature. The analytes in the surfactant-rich phase were concentrated with the help of centrifugation and directly analyzed by high performance liquid chromatography with UV detection. None of potentially hazardous organic solvents was used in the whole sample preparation procedure. The significant variables for the performance of extraction and concentration were studied. The limits of detection of SAs obtained are in the range of 3.2–5.7ngg−1. The relative standard deviations of intra- and inter-day tests ranging from 3.5% to 7.7% and from 4.6% to 9.5% are obtained, respectively. This method was applied to the determination of SAs in some soil samples with different characteristics. The SAs recoveries obtained at fortified level of 100ngg−1 for these samples are in the range of 81.2–93.7%. The effect of ageing time of spiked soil samples on the SAs recoveries was examined by the proposed method and a method reported in the literature. The recoveries of SAs decreased when the ageing time changed from 1 day to 4 weeks. [ABSTRACT FROM AUTHOR]

Abstract: A method based on coupling of cloud point extraction (CPE) with high performance liquid chromatography separation and ultraviolet detection was developed for determination of xanthohumol in beer. The nonionic surfactant Triton X-114 was chosen as the extraction medium. The parameters affecting the CPE were evaluated and optimized. The highest extraction yield of xanthohumol was obtained with 2.5% of Triton X-114 (v/v) at pH 5.0, 15% of sodium chloride (w/v), 70°C of equilibrium temperature and 10min of equilibrium time. Under these conditions, the limit of detection of xanthohumol is 0.003mgL−1. The intra- and inter-day precisions expressed as relative standard deviations are 4.6% and 6.3%, respectively. The proposed method was successfully applied for determination of xanthohumol in various beer samples. The contents of xanthohumol in these samples are in the range of 0.052–0.628mgL−1, and the recoveries ranging from 90.7% to 101.9% were obtained. The developed method was demonstrated to be efficient, green, rapid and inexpensive for extraction and determination of xanthohumol in beer. [Copyright &y& Elsevier]

Abstract: The magnetic mixed hemimicelles solid-phase extraction (MMHSPE), based on the adsorption of cation surfactant octadecyltrimethylammonium bromide (OTMABr) onto magnetite nanoparticles (Fe3O4 NPs) to form mixed hemimicelles, was proposed for the preconcentration of several sulfonamides (SAs) compounds including sulfamethoxazole (SMX), sulfamethoxydiazine (SMD), sulfadimethoxine (SDM) and sulfaquinoxaline (SQX) from environmental water samples. This method avoided the time-consuming column-passing process of loading large volume samples in traditional SPE through the rapid isolation of OTMABr-coated Fe3O4 NPs with an adscititious magnet. Mixed hemimicelles formed on the surface of Fe3O4 NPs by OTMABr showed great adsorptive tendency towards analytes. The OTMABr-coated Fe3O4 NPs adsorbents were easy to be prepared, low cost and environmentally friendly. A comprehensive study on the adsorption conditions such as the amount of the surfactant, the solution pH, the desorption condition and the maximum extraction sample volume were optimized. A concentration factor of 1000 was achieved by the extraction of 500mL of environmental water samples using MMHSPE. Detection limits obtained for SMX, SMD, SDM and SQX were 0.026, 0.024, 0.033 and 0.030μgL−1, respectively. Good recoveries (70–102%) with low relative standard deviations (1–6%) were achieved in analyzing spiked water samples. Low concentration of SQX was found in hospital primary and final sewage effluent sample. [Copyright &y& Elsevier]

Abstract: The high-performance liquid chromatography (HPLC) coupled with on-line solid phase extraction (SPE) and ultraviolet (UV) detection was developed for determining andrographolide and dehydroandrographolide in rabbit plasma. Plasma samples (100μL) were injected directly into a C18 SPE column and the biological matrix was washed out for 6min using 15% aqueous methanol. By rotation of the switching valve, andrographolide and dehydroandrographolide were eluted in the back-flush mode and transferred to the analytical column by the chromatographic mobile phase consisted of methanol:acetonitrile (ACN):water (50:10:40; v/v). The UV detection was performed at 225nm. The calibration curves showed excellent linear relationship (R ≥0.9993) over the concentration range of 0.05–5.0μgmL−1. The within- and between-day precisions (R.S.D.) of two analytes were in the range of 1.2–6.5% and the accuracies were between 92.0% and 102.1%. Their recoveries were all greater than 94%. The limits of detection were 0.019μgmL−1 for andrographolide and 0.022μgmL−1 for dehydroandrographolide. This method was successfully applied to the plasma concentration–time curve study after oral administration of Andrographis paniculata Nees extract in rabbit. [Copyright &y& Elsevier]

A silica-based surface magnetic molecularly imprinted polymer for the selective recognition of parabens was prepared using a facile and general method that combined atom-transfer radical polymerization with surface imprinting technique. The prepared magnetic molecularly imprinted polymer was characterized by transmission electron microscopy, Fourier transform infrared spectrometry and physical property measurement. The isothermal adsorption experiment and kinetics adsorption experiment investigated the adsorption property of magnetic molecularly imprinted polymer to template molecule. The four parabens including methylparaben, ethylparaben, propylparaben, and butylparaben were used to assess the rebinding selectivity. An extraction method, which used magnetic molecularly imprinted polymer as adsorbents coupled with high-performance liquid chromatography for the determination of the four parabens in fruit juice samples was developed. Under the optimal conditions, the limits of detections of the four parabens were 0.028, 0.026, 0.021, and 0.026 mg/L, respectively. The precision expressed as relative standard deviation ranging from 2.6 to 8.9% was obtained. In all three fortified levels, recoveries of parabens were in the range of 72.5-89.4%. The proposed method has been applied to different fruit juice samples including orange juice, grape juice, apple juice and peach juice, and satisfactory results were obtained. [ABSTRACT FROM AUTHOR]

Abstract: A cloud point extraction method was developed for extraction of formaldehyde in beer prior to high performance liquid chromatography analysis. The formaldehyde was taken into complex with 2,4-dinitrophenylhydrazine in aqueous nonionic surfactant Triton X-114 medium and concentrated in the surfactant-rich phase by bringing the solution to the temperature of 60°C. Under optimal conditions, the limit of detection of formaldehyde is 0.7ngmL−1. The intra- and inter-day precisions expressed as relative standard deviations are 4.2% and 5.5%, respectively. The proposed method was successfully applied for determination of formaldehyde in various beer samples. The contents of formaldehyde in these samples are in the range of 172–385ngmL−1. The results were in agreement with those obtained by the state standard method (steam-distillation and spectrophotometry analysis) used in China. The developed method was demonstrated to be rapid and sensitive for extraction and determination of formaldehyde in beer. [Copyright &y& Elsevier]

Abstract: A method was developed using magnetic strong cation-exchange resin modified with 2,4-dinitrophenylhydrazine (DNPH) for the determination of formaldehyde (HCHO) in fruit juice samples. The procedures of extraction and derivatization were carried out in a single step by stirring the resins and diluted fruit juice with water. When the procedures were completed, the resins adsorbing the HCHO–DNPH derivative were easily separated from the sample matrix by an adscititious magnet. The HCHO–DNPH derivative eluted from the resins was directly determined by high-performance liquid chromatography with UV detector at 360nm. The limit of detection of the proposed method in fruit juice obtained is 6.0ngmL−1. In this work, the volume of fruit juice was 5mL and the amount of MSCX resins was 100mg, and the resins can be reused 10 times. The relative standard deviations of intra-day and inter-day ranging from 3.9% to 6.1% and from 4.2% to 7.0% are obtained, respectively. The recovery of HCHO in the analysis of spiked fruit juice samples is in the range of 85.7–100.4%. [Copyright &y& Elsevier]