A novel solid-phase microextraction fiber was prepared using graphene oxide/β-cyclodextrin (GO/β-CD) composite as a coating material immobilized on a stainless steel wire using sol–gel technique. The coating has large surface area with uniform porous structure, stable performance at high temperature, and good coating preparation reproducibility. The prepared GO/β-CD sol–gel stainless steel fiber used as a headspace solid phase microextraction (HS-SPME) fiber was evaluated by the determination of organophosphate ester flame retardants (OPFRs) in water samples coupled to a gas chromatography/nitrogen phosphorus detector (GC/NPD). The studied OPFRs have a wide range of polarities and volatilities, and are not easily extracted by conventional commercial SPME fibers simultaneously. The prepared GO/β-CD SPME fiber showed good extraction performance for all the studied OPFRs. The developed HS-SPME-GC/NPD method provided low limits of detection ranging between 1.1 and 60.4 ng L−1. Good intra- and inter-day precision expressed as relative standard deviations for a single fiber were in the range of 2.2–9.6% and 2.7–9.7%, respectively, and fiber-to-fiber reproducibility was in the range of 6.3–10.9%. The calibration curves were linear in the concentration range from 10 to 50 000 ng L−1 (R > 0.9955). The developed method was applied for the analysis of tap, lake and river water samples and the relative recoveries were found to be in the range from 82.1 to 116.9%. Based on these features, the proposed fiber has great potential for widespread use as an effective and useful extraction tool.

•PD/DAS/CHI coating material was prepared in a chemical resistant PTFE tube.•PD/DAS/CHI coating functionalized PTFE tube was used for IT-SPME-ISD for analysis of liver cancer biomarkers.•PD/DAS/CHI modified PTFE tube showed good enrichment performance and stability.In order to highly enrich two liver cancer biomarkers (hexanal and 2-butanone) in human blood, in this study, natural nontoxic polydopamine/dialdehyde starch/chitosan (PD/DAS/CHI) coating material was synthesized and immobilized on the inner wall of polytetrafluoro-ethlyene (PTFE) tube. It was used to develop the method based on in-tube solid-phase microextraction (IT-SPME) with in-situ derivatization (ISD) coupled to high performance liquid chromatography for the determination of the above mentioned two liver cancer biomarkers in human blood. The simple, rapid and sensitive IT-SPME-ISD method can be finished within 11 min. Under optimum conditions, the limits of detection (LODs) were 1.4 and 1.6 nmol L−1 for hexanal and 2-butanone, respectively. The relative recoveries from real human blood samples were in the range from 70% to 91% with the intra- and inter-day precisions less than 7.2%. Furthermore, this method was successfully applied for the analysis of hexanal and 2-butanone in blood samples from healthy people with 0.42 ± 0.05 and 0.34 ± 0.04 μmol L−1, while liver cancer patients with 1.90 ± 0.07  μmol L−1 and 0.91 ± 0.07 μmol L−1, respectively. The t-test's results showed there is a statistically significant difference between the data from healthy persons and liver cancer patients. Hence, the developed method might be applied in the screening of suspected liver cancer patients.Schematic of preparing PDA/DAS/CHI modified PTFE tube.Figure optionsDownload full-size imageDownload as PowerPoint slide

⿢GO coating bonded onto a stainless steel was fabricated by sol-gel technique.⿢The GO based sol-gel fiber was used as HS-SPME sorbent to extract OPFRs from environmental water samples.⿢The GO based sol-gel fiber exhibited good extraction performance.In this paper, graphene oxide was coated onto a stainless steel wire through sol-gel technique and it was used as a solid phase microextraction (SPME) fiber. The prepared fiber was characterized by scanning electron microscopy (SEM), which displayed that the fiber had crinkled surface and porous structure The application of the fiber was evaluated through the headspace SPME of nine organophosphate ester flame retardants (OPFRs) with different characteristics in water samples followed by gas chromatography and nitrogen-phosphorous detector (GC/NPD). The major factors influencing the extraction efficiency, including the extraction and desorption conditions, were studied and optimized. Under the optimum conditions, the proposed method was evaluated, and applied to the analysis of organophosphate ester flame retardants in real environmental water samples. The results demonstrated the HS-SPME method based on GO sol-gel fiber had good linearity (R > 0.9928), and limits of detection (1.4⿿135.6 ng L⿿1), high repeatability (RSD < 9.8%) and good recovery (76.4⿿112.4%). The GO based sol-gel fiber displayed bigger extraction capability than the commercial PDMS fiber and the pure sol-gel fiber for both polar and apolar organophosphate esters, especially for the OPFRs containing benzene rings.

We describe a new kind of polymer monolithic column for polymer monolith microextraction (PMME) of carbamate insecticide (methomyl, carbofuran and pirimicarb) residues from water samples. The monolith was prepared inside the tip of a micropipette via thermally initiated free-radical polymerization of methacrylic acid as the monomer, ethylene glycol dimethacrylate as the cross-linker, and graphene oxide (GO) dispersed in the mixed porogens (1-propanol and 1,4-butanediol). The resulting monolith was characterized by scanning electron microscopy and IR spectrometry. The effects of sample flow rate, sample volume, sample pH, desorption solvent and flow rate on PMME were optimized. Compared to a monolith without GO, the new monolith displays higher enrichment capacity, and is reusable and stable. Following extraction, the three carbamates were quantified by HPLC. The limits of detection (for S/N = 3) for the three carbamates are in the range of 0.3–0.7 μg∙L−1, and the intra- and inter-day precisions are <5.7 %. The new monolith was successfully applied for the determination of the insecticides in various (spiked) environmental water samples, with recoveries in the range from 78.9 to 103.4 %.

We describe a novel magnetic nanosorbent that consists of nanowires consisting of a core of metallic iron and an iron (III) oxide shell. These nanowires were then deposited on graphene oxide to form a composite of the type Fe@Fe2O3/GO. Specifically, the magnetic composite is formed via electrostatic interaction between negatively charged GO nanosheets and positively charged Fe@Fe2O3 nanowires in aqueous solution. The material was successfully applied to the extraction of the endocrine-disrupting phenols bisphenol A, triclosan and 2,4-dichlorophenol from water samples. Compared to neat graphene oxide, the composite material exhibits improved properties in terms of microextraction where both the hydrophilic graphene oxide and the Fe@Fe2O3 nanowires participate in the adsorption of the hydrophilic analytes. The amount of adsorbent, pH of water sample, extraction time and desorption time, type and volume of desorption solution were optimized. Following extraction for the absorbent, the phenols were quantified by HPLC. The three phenols can be determined in 0.5 to 100 ng∙mL−1 concentration range, with limits of detection (at an S/N ratio of 3) ranging from 0.08 to 0.10 ng∙mL−1. The repeatability was investigated by evaluating the intra- and inter-day precisions with relative standard deviations of lower than 7.5 % (n = 5). The recoveries from spiked real water samples were in the range from 84.8 to 92.0 %. The results indicate that the novel material can be successfully applied to the extraction and analysis of phenols from water samples.

•Fe3O4@CHI@PANI composite was prepared via facile coprecipitation and polymerization reaction methods.•Fe3O4@CHI@PANI composite showed high extraction efficiency for aromatic phenols.•Fe3O4@CHI@PANI composite showed good magnetic response.In the present study, chitosan (CHI) functionalized Fe3O4 magnetic microspheres coated with polyaniline (PANI) were synthesized for the first time. The chitosan-functionalized magnetic microspheres (Fe3O4@CHI) were synthesized by a co-precipitation method, and then aniline was polymerized on the magnetic core. The obtained Fe3O4@CHI@PANI microspheres were spherical core–shell structure with uniform size at about 100 nm with 20–30 nm diameter core. The microspheres had a high saturation magnetization of 32 emu g−1, which was sufficient for magnetic separation. The obtained Fe3O4@CHI@PANI magnetic microspheres were applied as magnetic adsorbents for the extraction of aromatic compounds via π–π interaction between polyaniline shell and aromatic compounds. Three endocrine-disrupting phenols, including bisphenol A (BPA), 2, 4-dichlorophenol (2, 4-DCP), and triclosan (TCS) were selected as the model analytes to verify the extraction ability of Fe3O4@CHI@PANI. The hydrophilic chitosan-functionalized Fe3O4 core (Fe3O4@CHI) improved the dispersibility of Fe3O4@CHI@PANI microspheres, and then improve its extraction efficiency. The dominant parameters affecting enrichment efficiency were investigated and optimized. Under optimal condition, the proposed method was evaluated, and applied to the analysis of phenols in real water and juice samples. The results demonstrated the method based on Fe3O4@CHI@PANI magnetic microspheres had good linearity (R2>0.996), and limits of detection (0.10–0.13 ng mL−1), high repeatability (RSD<6.6%) and good recovery (85.0–106.7%).

A novel dispersive micro-solid phase extraction (D-μ-SPE) method is presented in this paper. The most attractive feature of this method is taking full advantage of a plastic dropper and nanoscale one-dimensional polyaniline (1D-PANI). The plastic dropper was employed as both the extraction and preconcentration device. All procedures needed in the common μ-SPE were performed in a plastic dropper without any additional devices, such as a centrifuge, magnetic field and pressure blowing concentrator. So the operating steps were simplified greatly. 1D-PANIs were used as the sorbent. The huge surface and interconnected network structure of 1D-PANIs endows them with high dispersive adsorbability and good permeability for the adsorbed analytes to be eluted. To test the feasibility of the proposed method, eight organochlorine pesticides (OCPs) were selected as the model analytes for D-μ-SPE of OCPs in water samples. A series of extraction parameters have been investigated systematically. Under optimized conditions, the method showed that the linear correlation coefficients (r) were better than 0.9971 and the limits of detection (LODs) for eight OCPs ranged from 0.0121 to 0.0468 μg L−1. The intra- and inter-day relative standard deviations (RSDs) were less than 11.9%. The recoveries of OCPs for three spiked aqueous samples ranged from 73.6 to 107.0%. The novel D-μ-SPE is promising to be an alternative sample preparation method for extracting apolar analytes in complex sample matrices because of its simplicity, low cost and high extraction efficiency.

A novel low molecular weight methomyl molecule-imprinted monolith (MIM) was prepared inside a polypropylene pipette tip by polymerization reaction. Then the pipette tip-based MIM micro-solid-phase extraction (PT-MIM-μ-SPE) method was developed for selective extraction of methomyl in aqueous solution. The extraction parameters, such as the sample flow rate, sample volume and elution solvent, were investigated. By combining with a high performance liquid chromatography-ultraviolet detector, the PT-MIM-μ-SPE method showed a good linear range of 0.6–1000.0 μg L−1 with a low limit of detection of 0.2 μg L−1. The method was also applied for the pretreatment of methomyl in various environmental water samples. The relative recoveries were in the range of 84.9 to 105.1% with relative standard deviations less than 9.0%. The results showed that methomyl could be selectively enriched and monitored from environmental water samples.

A simple, rapid and sensitive strategy has been presented for the simultaneous determination of three fungicides (azoxystrobin, diethofencarb and pyrimethanil) in water samples by coupling polymer monolith microextraction (PMME) to high performance liquid chromatography. A novel poly(2-hydroxypropyl methacrylate-ethylene dimethacrylate) (HPMA-EDMA) monolithic capillary column was synthesized and selected as the extraction medium for the PMME. To achieve optimum extraction performance, the conditions of the PMME including sample flow rate, sample pH, eluent volume, eluent flow rate, sample volume and salt effect have been investigated. Under the optimum conditions, the limits of detection of azoxystrobin, diethofencarb and pyrimethanil are 0.19, 0.22 and 0.65 μg L−1, respectively. The reproducibility of the method was obtained with intra-day and inter-day relative standard deviations less than 3.1% and 6.3%, respectively. The proposed method has been successfully applied to the determination of the three fungicides in environmental water samples with a recovery range of 80.2–115.6% for all the samples.

A simple and sensitive method for the analysis of three chlorophenols (CPs) in toilet paper has been developed for the first time. Acetone was used as a solvent to extract the three CPs from toilet paper assisted by ultrasound irradiation. When the extraction process was finished, 0.5 mL acetone extract was subjected to synchronous derivative dispersive liquid–liquid microextraction (DLLME). During this process, the analytes were rapidly transferred from the acetone extract to another extraction solvent (chlorobenzene) for further clean-up and enrichment. Acetone could also act as a dispersant during the DLLME process, which combined the advantages of ultrasonic assisted extraction and DLLME appropriately. Different factors affecting the extraction efficiency and derivatization step were carefully optimized. Under optimal conditions, the limits of detection for 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol were 1.5 μg kg−1, 0.75 μg kg−1, 0.25 μg kg−1, respectively. Satisfactory linear ranges were observed from 5–500 μg kg−1, 2.5–250 μg kg−1, 1–20 μg kg−1, respectively. Recoveries of three CPs in toilet paper were in the range 70.9–118%. The optimized method was successfully applied to three different toilet paper samples, and pentachlorophenol has been detected in one of the tested toilet papers at a concentration level of 1.2 μg kg−1.

•MIP sorbents using difenoconazole as the template have not been reported.•The application of MIP–PMME in food sample preparation is not frequent.•Difenoconazole-imprinted polymer monolith was synthesized in a pipette tip for the first time.A pipette tip-based molecularly imprinted polymer monolith microextraction (PT–MIPMME) method was developed for the selective extraction of difenoconazole in tap water and grape juice. In this method, molecularly imprinted polymer (MIP) monolith used as the sorbent was synthesized at the tip of a micropipette. This in situ polymerization reaction used difenoconazole as the template and methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker and the mixture of toluene–dodecanol as the porogenic solvent. The pipette tip containing MIP monolith was matched to a syringe for performing the polymer monolith microextraction (PMME). Several parameters affecting the proposed PT–MIPMME method were investigated, including the flow rate, sample volume, pH and salt concentration of sample, the type and volume of eluent. Under the optimal conditions, the PT–MIPMME method showed a low limit of detection of 0.5 μg L−1. The recoveries were in the range of 87.6–95.4% with relative standard deviations less than 4.9%. The results showed that difenoconazole was selectively enriched from tap water and grape juice samples.

•We assembled two simple apparatuses to form a new combining apparatus.•The two simple apparatuses are laboratory accessible.•The new combining apparatus collected the low-density extractant conveniently.•The LOQs of the method are low and the extraction time is short.•The new combining apparatus performed MSA-DLLME method well.This study introduced a simple combining apparatus for performing a magnetic stirring-assisted dispersive liquid–liquid microextraction (MSA-DLLME) for the detection of trace carbamate and organophosphorus pesticides in tea drinks coupled with high performance liquid chromatography. The simple combining apparatus was made up of a sample vial and a cut plastic dropper. The bulb end of the cut plastic dropper was inserted into the neck of the sample vial and the open tip end of the plastic dropper was then cut to an appropriate length. The combining apparatus made was then used to perform the MSA-DLLME. In this experiment, 1-octanol was injected into the tea drink sample solution and the extraction process accelerated by magnetic agitation. The sample solution turned clear and separated into two layers after leaving it alone for several minutes. The cut plastic dropper was gently put down into the sample vial, and then the liquid level of the sample solution elevated up to the tip of the plastic dropper for the collection of low-density extractant. Finally, the collected extractant was drawn out by a microsyringe and injected into the high performance liquid chromatography-diode-array detector for analysis. A series of extraction parameters were investigated and optimized. Under the most favorable conditions, high enrichment factors were obtained for carbofuran, carbaryl and isocarbophos (between 130 and 185). The limits of detection (S/N = 3) were in the range of 0.13–0.61 μg L−1, and the relative standard deviation varied below 7.8% (n = 5). Additionally, good recoveries were obtained between 79.4% and 114.4% in the three tea drinks. The simple combining apparatus utilized in this MSA-DLLME method was shown to be economical, fast, and convenient for the collection of low density extractant.

A very simple and effective method for the extraction and determination of oleanolic acid (OA) and ursolic acid (UA) in Radix Actinidiae chinensis was developed using ultrasound-assisted dispersive liquid–liquid microextraction (UA-DLLME) and high performance liquid chromatography–mass spectrometry (HPLC–MS). Ethanol was used as the solvent to extract OA and UA from Radix Actinidiae chinensis, assisted by ultrasonic waves. When the extraction process was finished, the two target analytes in the extraction solvent were rapidly transferred from the ethanol extract to another extraction solvent (chloroform) with the help of a dispersive solvent (tetrahydrofuran) by using DLLME. A series of extraction parameters were investigated and optimized. Under the most favorable conditions, the limits of detection (LOD, S/N = 3) and enrichment factors were 2.0 ng g−1, 89.4 and 6.0 ng g−1, 84.5 for OA and UA, respectively. The recoveries of the spiked sample solutions at three different concentration levels of 200, 500 and 1000 ng g−1 ranged between 88.2 and 96.6%. The proposed method was the first successfully applied for the extraction and determination of OA and UA in Radix Actinidiae chinensis.

Recently developed technique of vortex-assisted liquid–liquid microextraction (VALLME) has thus far proven to be efficient for the rapid extraction of trace amounts of organic pollutants with both high enrichment factors and low detection limits. In this paper, a new and easy one-step in-syringe device for VALLME has been proposed and applied for the analysis of three fungicides in real aqueous samples. This novel technique performed extraction, separation, preconcentration, and injection in one step using a 5 mL syringe, thus expanding the level of automation of VALLME. The practicality of the technique was evaluated through the analysis of three fungicides (azoxystrobin, diethofencarb, and pyrimethanil) in aqueous samples by high performance liquid chromatography-diode array detection. 1-octanol was used as the extractant. Under the optimized conditions, the limits of detection and enrichment factors were 0.96 μg L−1, 144 for azoxystrobin, 1.33 μg L−1, 183 for diethofencarb, and 0.73 μg L−1, 176 for pyrimethanil. Good reproducibility expressed as the intra-day and inter-day precisions (RSD) at 40 μg L−1 concentration level were below 4.0% and 6.1% (n = 6). The recoveries of the spiked real water samples at three different concentration levels of 4, 10, 40 μg L−1 ranged from 91.6–116.8%, 81.3–107.3% and 81.4–104.4%, respectively.

An in-syringe demulsified dispersive liquid–liquid microextraction (ISD–DLLME) technique was developed using low-density extraction solvents for the highly sensitive determination of the three trace fungicides (azoxystrobin, diethofencarb and pyrimethanil) in water samples by high performance liquid chromatography–mass spectrometry chromatography–diode array detector/electrospray ionisation mass spectrometry. In the proposed technique, a 5-mL syringe was used as an extraction, separation and preconcentration container. The emulsion was obtained after the mixture of toluene (extraction solvent) and methanol (dispersive solvent) was injected into the aqueous bulk of the syringe. The obtained emulsion cleared into two phases without centrifugation, when an aliquot of methanol was introduced as a demulsifier. The separated floating organic extraction solvent was impelled and collected into a pipette tip fitted to the tip of the syringe. Under the optimal conditions, the enrichment factors for azoxystrobin, diethofencarb and pyrimethanil were 239, 200, 195, respectively. The limits of detection, calculated as three times the signal-to-noise ratio (S N−1), were 0.026 μg L−1 for azoxystrobin, 0.071 μg L−1 for diethofencarb and 0.040 μg L−1 for pyrimethanil. The repeatability study was carried out by extracting the spiked water samples at concentration levels of 0.02 μg mL−1 for all the three fungicides. The relative standard deviations varied between 4.9 and 8.2% (n = 5). The recoveries of all the three fungicides from tap, lake and rain water samples at spiking levels of 0.2, 1, 5 μg L−1 were in the range of 90.0–105.0%, 86.0–114.0% and 88.6–110.0%, respectively. The proposed ISD–DLLME technique was demonstrated to be simple, practical and efficient for the determination of different kinds of fungicide residues in real water samples.Graphical abstractHighlights► The pretreatment apparatus is the first introduced. ► The pipette tip is a efficient preconcentration tool. ► The LOQ of the proposed technique is very low.

We have developed a simple method for the microextraction of the carbamate pesticides carbofuran, pirimicarb, and carbaryl. It is termed ionic liquid magnetic bar microextraction (ILMB-ME) and based on an ionic liquid deposited on a magnetic stirrer bar placed in a sealed short PCR tube into which microholes where pinned. When placed in a vial containing the aqueous sample solution, the ILMB tumbles freely in the aqueous solution and the carbamates are extracted into the ionic liquid phase which then was determined by HPLC. The enrichment factors for carbofuran, pirimicarb, and carbaryl are 107, 94, 95, respectively. The limits of detection, calculated as three times the signal-to-noise ratio (S/N), are 1.4 μg L−1 for carbofuran, 3.4 μg L−1 for pirimicarb, and 1.7 μg L−1 for carbaryl. The repeatability, carried out by extracting water samples spiked with carbamate levels of 200 μg L−1, yielded relative standard deviations between 2.9 and 6.0 %, (for n = 5). The recoveries of all the three fungicides from tap, lake and rain water samples at spiking levels of 5 and 50 μg L−1 are in the range from 86 to 98 %, and from 80 to 96 %, respectively. We conclude that this is a simple, practical and efficient method for the determination of fungicide residues in real water samples.

In this work, a simple, practical and environmentally friendly sample pre-treatment method, ultrasound-assisted surfactant-enhanced emulsification microextraction coupled with high performance liquid chromatography–diode array detector/electrospray ionisation mass spectrometry, was developed to determine diethofencarb and pyrimethanil residues in water and fruit juice samples. Tween 80 was used as an emulsifier and carbon tetrachloride was chosen as the extraction solvent, and no dispersive organic solvent was needed, which is typically required in common dispersive liquid–liquid microextraction methods. Several variables, such as the type and volume of extraction solvent and surfactant, extraction temperature and ultrasound extraction time were investigated and optimised. Under optimal conditions, the enrichment factors were 265 and 253 for diethofencarb and pyrimethanil, respectively. The limits of detection (LODs), calculated as three times the signal-to-noise ratio (S/N), were 0.01 μg L−1 for both diethofencarb and pyrimethanil. The linearity of the method was obtained in the range of 0.05–2000 μg L−1, with correlation coefficients of 0.9994–0.9998. The water (at fortified levels of 0.1 and 1.0 μg L−1) and fruit juice samples (at fortified levels of 0.1 and 1.0 μg L−1) were successfully analysed using the proposed method, and the relative recoveries were in the range of 88–114%, 93–111%, 86–117% and 94–101%, respectively.Graphical abstractHighlights► A UASEME is used as a pre-treatment method of water and fruit juice samples. ► Diethofencarb and pyrimethanil fungicides are target analytes. ► HPLC–DAD/ESI-MS detection is used to detect and confirm the residual levels. ► The proposed method presents low LODs, good repeatability, good recoveries. ► The residues can be founded in some water samples.

A novel ultrasound-assisted surfactant-enhanced emulsification microextraction (UASEME) technique has been proposed by using low-density extraction solvents. In the proposed technique, Tween 80 and cyclohexane were injected into 5-mL glass test tubes with conical bottoms, containing 5.00 mL of a water sample that was located inside the ultrasonic bath. When the extraction process was finished, the glass test tube was sealed with a rubber plug and then placed upside down in a centrifuge. The finely dispersed droplets of cyclohexane collected at the conical bottom of test tube because the density of cyclohexane is less than of water, and the PAHs were concentrated in the cyclohexane. Next, 5 μL of the cyclohexane that collected at the conical bottom was removed using a 10-μL microsyringe and injected into high performance liquid chromatography coupled with fluorescence detection (HPLC-FLD) for analysis. The proposed method avoided the use of chlorinated solvents, which have been widely used as extraction solvents in a normal UASEME assay. Parameters that affected the extraction efficiency, such as the type and volume of the extraction solvent, the type and concentration of the surfactant, and the ultrasound emulsification time and salt addition, were investigated and optimised for the method. Under the optimum conditions, the enrichment factors ranged between 90 and 247. The limits of detection of the method were 0.6–62.5 ng L−1. Good recoveries and repeatability of the method for the eleven PAHs were also obtained. The proposed UASEME technique has been demonstrated to be simple, practical and environmentally friendly for the determination of PAH residues in real water samples.

A sensitive method has been established for the determination of the pyrethroids (fenpropathrin and permethrin) in water samples. It is based on microextraction using monoliths composed of a poly-(glycidyl methacrylate-co-ethylene dimethacrylate) copolymer, and on detection by gas chromatography coupled to electron-capture detection. Experimental parameters including the flow rate and volume of the samples, the type, volume and flow rate of eluent and effect of salt addition were optimized. The limits of detection for fenpropathrin and permethrin are 0.5 and 2.7 ng mL−1, respectively. The intra-day and inter-day precisions were less than 5.5% and 9.0%. The method was successfully applied to determination of two pyrethroids in the tap and lake water samples and the accuracy was evaluated by recovery experiments.

A dispersive liquid-liquid microextraction method was developed for the determination of fungicides (diethofencarb and pyrimethanil) in aqueous samples. It is based on the use of solidified floating organic drops combined with high-performance liquid chromatography. Extraction solvent and dispersive solvent, extraction time and salt effect were optimized. Under optimized conditions, the enrichment factors for a 5 mL water sample are between 145 and 161. The limits of detection for diethofencarb and pyrimethanil are 0.24 and 0.09 μg ∙ L−1, respectively. The method offers good repeatability and high recovery. Compared with dispersive liquid-liquid microextraction, it has a higher enrichment factor, high precision due to the ease with which the solidified floating phase is transferred, thus avoiding the loss of analyte. Toxic solvents were replaced by 1-dodecanol with its much lower toxicity. The method has been successfully applied to the determination of the two fungicides in tap water, lake water, and river water.

In this paper, polychlorinated biphenyl (PCB), organochlorine pesticide (OCP) and pyrethroid pesticides in peach was investigated by comparing their residual level in peach juice, pulps and peels using dispersive liquid–liquid microextraction based on solidification of floating organic droplet (DLLME-SFO) combined with gas chromatography-electron capture detection (GC-ECD). Extraction conditions such as the type of extractant, volume of extractant and dispersant, salt effect and extraction time were optimized. For juice samples, the linearity of the method was obtained in the range of 10–2000 ng L−1,with determination coefficients > 0.99. The limits of detection (LOD) of the method were ranged between 2.8 and 18.5 ng L−1. For pulp and peel samples, the developed method is linear over the range assayed, 1–20 μg kg−1,with coefficients also >0.99. The relative recoveries of compounds analyzed from juice, pulp and peel samples were in the range of 73–106% with a relative standard deviation between 2.6 and 11.8%. The proposed method was applied to the simultaneous analysis of residues in real peach juice, pulp and peel samples. As a result, there were no target analytes found in peach juices and pulps while 3.3 μg kg−1 cyhalothrin and 3.5 μg kg−1 fenvalerate were found in peels. The experiment results revealed that the pyrethroid residues just deposited on the peels of the fruits, but did not move into pulps and juices.

Dispersive liquid–liquid microextraction (DLLME) based on the solidification of floating organic droplets (DLLME-SFO) combined with gas chromatography-electron-capture detection (GC–ECD) has been developed for extraction and analysis of three dinitrobenzenes. The extraction conditions including extraction solvent, disperser solvent, extraction time, salt effect and temperature were investigated and optimized systematically. The limits of detection were 0.019 μg L−1 for 1,4-dinitrobenzene, 0.079 μg L−1 for 1,3-dinitrobenzene and 0.034 μg L−1 for 1,2-dinitrobenzene. Moreover, it offered good repeatability and high recovery. This method was successfully applied to monitor DNBs in different water samples.

A very simple and effective method for the extraction and determination of oleanolic acid (OA) and ursolic acid (UA) in Radix Actinidiae chinensis was developed using ultrasound-assisted dispersive liquid–liquid microextraction (UA-DLLME) and high performance liquid chromatography–mass spectrometry (HPLC–MS). Ethanol was used as the solvent to extract OA and UA from Radix Actinidiae chinensis, assisted by ultrasonic waves. When the extraction process was finished, the two target analytes in the extraction solvent were rapidly transferred from the ethanol extract to another extraction solvent (chloroform) with the help of a dispersive solvent (tetrahydrofuran) by using DLLME. A series of extraction parameters were investigated and optimized. Under the most favorable conditions, the limits of detection (LOD, S/N = 3) and enrichment factors were 2.0 ng g−1, 89.4 and 6.0 ng g−1, 84.5 for OA and UA, respectively. The recoveries of the spiked sample solutions at three different concentration levels of 200, 500 and 1000 ng g−1 ranged between 88.2 and 96.6%. The proposed method was the first successfully applied for the extraction and determination of OA and UA in Radix Actinidiae chinensis.

A simple, rapid and sensitive strategy has been presented for the simultaneous determination of three fungicides (azoxystrobin, diethofencarb and pyrimethanil) in water samples by coupling polymer monolith microextraction (PMME) to high performance liquid chromatography. A novel poly(2-hydroxypropyl methacrylate-ethylene dimethacrylate) (HPMA-EDMA) monolithic capillary column was synthesized and selected as the extraction medium for the PMME. To achieve optimum extraction performance, the conditions of the PMME including sample flow rate, sample pH, eluent volume, eluent flow rate, sample volume and salt effect have been investigated. Under the optimum conditions, the limits of detection of azoxystrobin, diethofencarb and pyrimethanil are 0.19, 0.22 and 0.65 μg L−1, respectively. The reproducibility of the method was obtained with intra-day and inter-day relative standard deviations less than 3.1% and 6.3%, respectively. The proposed method has been successfully applied to the determination of the three fungicides in environmental water samples with a recovery range of 80.2–115.6% for all the samples.

Recently developed technique of vortex-assisted liquid–liquid microextraction (VALLME) has thus far proven to be efficient for the rapid extraction of trace amounts of organic pollutants with both high enrichment factors and low detection limits. In this paper, a new and easy one-step in-syringe device for VALLME has been proposed and applied for the analysis of three fungicides in real aqueous samples. This novel technique performed extraction, separation, preconcentration, and injection in one step using a 5 mL syringe, thus expanding the level of automation of VALLME. The practicality of the technique was evaluated through the analysis of three fungicides (azoxystrobin, diethofencarb, and pyrimethanil) in aqueous samples by high performance liquid chromatography-diode array detection. 1-octanol was used as the extractant. Under the optimized conditions, the limits of detection and enrichment factors were 0.96 μg L−1, 144 for azoxystrobin, 1.33 μg L−1, 183 for diethofencarb, and 0.73 μg L−1, 176 for pyrimethanil. Good reproducibility expressed as the intra-day and inter-day precisions (RSD) at 40 μg L−1 concentration level were below 4.0% and 6.1% (n = 6). The recoveries of the spiked real water samples at three different concentration levels of 4, 10, 40 μg L−1 ranged from 91.6–116.8%, 81.3–107.3% and 81.4–104.4%, respectively.

A novel dispersive micro-solid phase extraction (D-μ-SPE) method is presented in this paper. The most attractive feature of this method is taking full advantage of a plastic dropper and nanoscale one-dimensional polyaniline (1D-PANI). The plastic dropper was employed as both the extraction and preconcentration device. All procedures needed in the common μ-SPE were performed in a plastic dropper without any additional devices, such as a centrifuge, magnetic field and pressure blowing concentrator. So the operating steps were simplified greatly. 1D-PANIs were used as the sorbent. The huge surface and interconnected network structure of 1D-PANIs endows them with high dispersive adsorbability and good permeability for the adsorbed analytes to be eluted. To test the feasibility of the proposed method, eight organochlorine pesticides (OCPs) were selected as the model analytes for D-μ-SPE of OCPs in water samples. A series of extraction parameters have been investigated systematically. Under optimized conditions, the method showed that the linear correlation coefficients (r) were better than 0.9971 and the limits of detection (LODs) for eight OCPs ranged from 0.0121 to 0.0468 μg L−1. The intra- and inter-day relative standard deviations (RSDs) were less than 11.9%. The recoveries of OCPs for three spiked aqueous samples ranged from 73.6 to 107.0%. The novel D-μ-SPE is promising to be an alternative sample preparation method for extracting apolar analytes in complex sample matrices because of its simplicity, low cost and high extraction efficiency.

A novel low molecular weight methomyl molecule-imprinted monolith (MIM) was prepared inside a polypropylene pipette tip by polymerization reaction. Then the pipette tip-based MIM micro-solid-phase extraction (PT-MIM-μ-SPE) method was developed for selective extraction of methomyl in aqueous solution. The extraction parameters, such as the sample flow rate, sample volume and elution solvent, were investigated. By combining with a high performance liquid chromatography-ultraviolet detector, the PT-MIM-μ-SPE method showed a good linear range of 0.6–1000.0 μg L−1 with a low limit of detection of 0.2 μg L−1. The method was also applied for the pretreatment of methomyl in various environmental water samples. The relative recoveries were in the range of 84.9 to 105.1% with relative standard deviations less than 9.0%. The results showed that methomyl could be selectively enriched and monitored from environmental water samples.

A simple and sensitive method for the analysis of three chlorophenols (CPs) in toilet paper has been developed for the first time. Acetone was used as a solvent to extract the three CPs from toilet paper assisted by ultrasound irradiation. When the extraction process was finished, 0.5 mL acetone extract was subjected to synchronous derivative dispersive liquid–liquid microextraction (DLLME). During this process, the analytes were rapidly transferred from the acetone extract to another extraction solvent (chlorobenzene) for further clean-up and enrichment. Acetone could also act as a dispersant during the DLLME process, which combined the advantages of ultrasonic assisted extraction and DLLME appropriately. Different factors affecting the extraction efficiency and derivatization step were carefully optimized. Under optimal conditions, the limits of detection for 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol were 1.5 μg kg−1, 0.75 μg kg−1, 0.25 μg kg−1, respectively. Satisfactory linear ranges were observed from 5–500 μg kg−1, 2.5–250 μg kg−1, 1–20 μg kg−1, respectively. Recoveries of three CPs in toilet paper were in the range 70.9–118%. The optimized method was successfully applied to three different toilet paper samples, and pentachlorophenol has been detected in one of the tested toilet papers at a concentration level of 1.2 μg kg−1.