Microextraction Column Research Articles

Task specific microextraction column based on monolith for magnetic field-assisted in-tube solid phase microextraction of vanadium species in complex samples prior to online chromatographic analysis

The dominant species of vanadium (V) are V(IV) and V(V) which exhibit different toxicity and biological effects. Thus, speciation of V(IV) and V(V) is highly essential. Efficient sample preparation is the core step in the quantification of V(IV) and V(V). In the present study, a new task specific microextraction column based on monolith mingled with Fe3O4 nanoparticles (MBMC) was in situ synthesized in capillary and utilized as the extraction phase of magnetic field-assisted in-tube solid phase microextraction (MA-IT-SPME) of V(IV) and V(V) species which were coordinated with ethylene diamine tetraacetic acid (EDTA). The prepared MBMC presented porous and superparamagnetic properties, and possessed abundant functional groups. Results revealed that the exertion of magnetic field during adsorption and eluting steps boosted the extraction efficiency of V(IV)-EDTA and V(V)-EDTA chelates from 65.1 % to 55.7 %–90.0 % and 80.1 %, respectively. Under the beneficial extraction parameters, the established MA-IT-SPME was online hyphenated with HPLC/DAD to perform speciation of trace vanadium in water and vegetable samples, the achieved limits of detection were 0.054–0.060 μg/L and 1.4–1.5 μg/kg in water and vegetable samples, respectively, and the spiked recoveries varied from 82.5 to 118 %. In addition, relevant extraction mechanism under magnetic field was explored. In comparison with existing methods, the developed MA-IT-SPME technique displays some attractive merits such as automation, good anti-interference ability, high extraction efficiency, low cost and less use of organic solvent, in the capture of V species. The established online MBMC@MA-IT-SPME-HPLC/DAD system can become a competitive approach for sensitive speciation of V(IV) and V(V) at trace levels in complex samples.

Syringe-based microextraction for the removal of vanadium from different water and food samples using newly synthesized imino diacetate functionalized polystyrene as a new adsorbent: A multivariate approach

In this work, a new imino diacetate functionalized polystyrene (PS-Plina-ida) was synthesized and used as adsorbent for the removal of vanadium. The long narrow column solid phase microextraction connected to the portable syringe (LCSPME-PSS) system consists of a microextraction column filled with a solid phase material, a syringe, and a connecting tube. The microextraction column is made of a long and narrow glass column filled with a solid phase material (PS-Plina-ida) that selectively binds the target analyte. The syringe is used to aspirate the sample into the microextraction column and to elute the extracted analyte into the syringe for analysis. SEM, 1HNMR, DSC, and FTIR techniques were used to characterization of PS-Plina-ida. The key variables such as pH, amount of PS-Plina-ida, the concentration of vanadium, and adsorption cycle (min) of the proposed method were studied by using RSM of the design of the experiment under the desired condition. The experimental data was checked by using various isothermal models to check their adsorption behavior. Kinetic and thermodynamic studies were also carried out. When the analytical competence was tested, a linear response with (r) 0.989 for ranges of 0.50 and 10 mg/L was observed. A low limit of detection (30 ng/L) and a high enhancement factor (100) were obtained. Different real samples (water and digested food) were used to evaluate the practical application of the reported method.

Adoption of new strategy for molecularly imprinted polymer based in-tube solid phase microextraction to improve specific recognition performance and extraction efficiency

In-tube solid phase microextraction (IT-SPME) utilizing molecularly imprinted polymers (MIPs) as extraction phase has received wide attention due to various merits. However, low extraction efficiency and unsatisfactory recognition performance have limited its extensive application. To circumvent the limitations, a new strategy that implementation of magnetic fields during extraction stage was introduced to improve the extraction efficiency and recognition performance of MIPs-based IT-SPME. Firstly, using 2,4-dinitroaniline (2,4-DNA) as model template, a MIP mingled with magnetic nanoparticles (Fe3O4) was in-situ prepared in a capillary and employed as the microextraction column of IT-SPME. In the second step, a magnetic coil was wrapped the as-prepared MIP-based microextraction column so as to produce variable magnetic fields in extraction step. Results revealed that the application of magnetic field during the adsorption step improved the specific extraction performance towards template. The extraction efficiency and imprinting factor towards 2,4-DNA increased from 58% and 2.5 to 81% and 3.1, respectively. Practicality of the introduced magnetism-assisted IT-SPME technique based on MIP was demonstrated by on-line hyphenating with HPLC/DAD to quantify trace 2,4-DNA in a variety of environmental waters. High sensitivity (limit of detection was 0.060 μg/L), good precision (RSDs were below 10%) and satisfactory recoveries (82.1–111%) were obtained. Furthermore, the possible selective extraction mechanism under magnetic fields was deduced.

Online measurement of tetraethyllead in aqueous samples utilizing monolith-based magnetism-enhanced in-tube solid phase microextraction coupled with chromatographic analysis

A new procedure that utilizing a preconcentration system based on magnetism-enhanced in-tube solid phase microextraction (ME/IT-SPME) and detection by HPLC with diode array detector (DAD) after liquid desorption from the microextraction column has been developed for the online measurement of tetraethyllead (TEL) in various aqueous samples. In this connection, according to the chemical features of TEL, porous monolith mingled with Fe3O4 nanoparticles were designed and synthesized in a silica capillary, and used as the microextraction column of ME/IT-SPME. To favor the implement of variable magnetic fields during extraction procedure, the as-prepared microextraction column was twined a magnetic coil. Results revealed that the exertion of magnetic field during the adsorption and eluting procedures assisted the extraction of TEL with an enhancement by 52% in extraction efficiency. Under the most beneficial conditions, the developed ME/IT-SPME was online hyphenated with HPLC/DAD to measure trace TEL in various aqueous samples. The limit of detection was 0.082 μg/L and the RSDs for precision were in the range of 6.3–8.5%. The recoveries with low, medium and high fortified levels varied from 80.6% to 95.0% with good repeatability. To the best of knowledge, this is the first study that using IT-SPME to extract TEL and then online quantification with HPLC/DAD.

Aptamer affinity-based microextraction in-line coupled to capillary electrophoresis mass spectrometry using a porous layer/nanoparticle -modified open tubular column

An aptamer affinity based microextraction column is developed to be directly in-line coupled to capillary electrophoresis-mass spectrometry (CE-MS) for analyzing mycotoxins in food samples. Single-stranded DNA aptamers for selective recognition of aflatoxin B1 (AFB1) and ochratoxin A (OTA) targets are co-immobilized via covalent bonds on the surface of the inlet end of a capillary, which is pre-modified with three-dimensional porous layer and gold nanoparticles to enhance the specific surface area and loading capacity. The outlet of the capillary is designed as a porous tip to serve as the spray source for injection to the mass spectrometry. All the necessary processes for pretreatment and analysis of a sample are accomplished in one injection, including aptamer affinity-based microextraction, CE separation and MS detection of analytes. AFB1 and OTA are simultaneously determined in a wide linear range with sample consumption of only 1 μL and the limit-of-detection as low as 1 pg/mL. The microextraction column exhibits excellent repeatability and stability, which can be used over 45 runs within a month with CE separation efficiency and only MS intensity slightly decreased. Mycotoxins in three kinds of cereal based infant foods are accurately analyzed using the proposed method. The study provides a robust and universal approach that would have potential applications in a variety of analytical fields based on selective molecular recognition coupling to CE-MS analysis.

Efficient As(V) and Hg(Ⅱ) removal from acidic wastewater by a sulphydryl functionalized UIO-66-NH2

Metal-organic frameworks (MOFs) have a high potential for removing heavy metal ions from wastewater. However, they could not remove opposite-charged metal species simultaneously by adsorption. In this study, a novel bifunctional MOF UIO-66-NH2(-SH) containing -NH2 and -SH functional groups (UIO-66-NH2(-SH), named Zr-DMBM) was fabricated by the ligand exchange method to serve as an adsorbent of electrostatically opposite As(V) and Hg(II). The structure-dependent adsorption of Zr-DMBM was optimised as Zr4+: BDC-NH2:-SH = 1:2:1 for As(V) and Hg(II). The removal rates of As(V) and Hg(II) were greater than 80 % over a wide pH range (pH = 1–9), with maximum adsorption capacities of 72.2 and 812.5 mg·g-1, respectively. For practical applications, microextraction column packing of Zr-DMBM was applied to efficiently and simultaneously remove As(V) and Hg(II) from wastewater. After As(V) and Hg(II) adsorption, the prepared column was easily regenerated using thiourea (0.1 M) and hydrochloric acid (0.1 M), and could be recycled five times without an evident reduction in adsorption capacity. The excellent performance of Zr-DMBM was attributed to the incorporation of -SH and –NH2 groups and its unique physicochemical properties. Moreover, X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicated that Zr-DMBM exhibited the same topological structure as UIO-66-NH2, and Fourier transform infrared spectroscopy (FTIR) confirmed the presence of -SH groups in its structure. The adsorption kinetics further demonstrated the strong electrostatic attraction between Zr-DMBM and As(V) and Hg(II). Therefore, the combination of MOFs with microextraction column technology is a promising candidate for the simultaneous removal of As(V) and Hg(II) ions from wastewater. Moreover, the sulfhydryl-functionalised UIO-66-NH2 is suitable for industrial wastewater treatment owing to its excellent performance in a broad range of pH environments.

Microextraction columns for automated sample preparation. A review focusing on fully miniaturized column switching and bioanalytical applications

• Novelties in sorptive phases for online microextraction columns are reviewed. • Advances in particulate, monolithic, open-tubular, and fibrous extraction media. • The development of fully miniaturized column switching approaches is highlighted. • Focus on modern bioanalytical applications of fully miniaturized column-switching. Column switching (CS) emerged as a strategy for direct injection of raw biological samples and currently is the more versatile technique for the fully automated integration of the sample preparation and the chromatography analysis. At the miniaturized scale, CS addresses the matrix complexity and allows the injection of sample volumes larger than those supported by the capillary/nano analytical columns. Detectability can be significantly improved while preserving the analytical capillary/nano column and the proper functioning of the instrument. In the last two decades, fully miniaturized CS systems have been under continuous development. Innovative polymeric, inorganic, and nanomaterials-based extraction phases have been introduced and exploited in diverse column formats, including particle-packed, monolithic, fiber-packed, and open tubular, extraction media. This paper reviews the more recent advances in microextraction column technology for fully miniaturized column-switching systems. Modern sorptive phases and extraction will be described, discussing their potentialities, advantages, and limitations. The overview will emphasize the significance of those developments in bioanalytical applications.

Speciation of organotin compounds in water and seafood samples by online hyphenation of porous polymer-based magnetism-enhanced in-tube solid phase microextraction and HPLC

A new strategy based on online hyphenation of magnetism-enhanced in-tube solid phase microextraction (ME-SPME) and HPLC was developed for speciation of organotin compounds (OTCs) in water and seafood samples. Task specific porous polymer embedded magnetic nanoparticles (TPM) was fabricated in capillary and utilized as the microextraction column (MEC) of ME-SPME. The implement of magnetic field during extraction duration obviously improved extraction efficiencies of prepared TPM/MEC towards studied TOCs from 48.0-77.0% to 84.2–99.7%. Under the optimized extraction parameters, sensitive and automatic approach for the quantification of TOCs was developed by online hyphenation of ME-SPME and HPLC with fluorescence detection. The limits of detection for water and seafood samples were in the ranges of 0.0030–1.5 μg/L and 0.71–14 μg/kg, respectively. The established method was employed to measure low contents of studied OTCs in actual samples, and the recoveries at different fortified contents varied from 80.2% to 116% with satisfactory reproducibility (RSDs below 10%). In addition, confirmation experiments were adopted to inspect the accuracy of introduced method.

Development of magnetism-assisted in-tube solid phase microextraction of phenolic acids in fruit juices prior to high-performance liquid chromatography quantification.

Magnetism-assisted in-tube solid phase microextraction based on porous monolith mingled with Fe3 O4 nanoparticles was developed for capture of phenolic acids in fruit juices. First, poly (1-allyl-3-methylimidazolium bis [(trifluoro methyl) sulfonyl] imide-co-ethylene dimethacrylate) monolith embedded with Fe3 O4 nanoparticles was facile fabrication in a capillary and employed as microextraction column. Subsequently, a magnetic coil adopted to produce variable magnetic fields during extraction stage was twined on the microextraction column. The analytes contents in eluant were quantified by high performance liquid chromatogram with diode array detector. Various parameters affecting the extraction performance were inspected and optimized in detail. Results revealed that the exertion of magnetic fields in adsorption and desorption steps enhanced the extraction efficiencies of analytes from 44.9-64.0% to 78.6-87.1%. Under the optimal extraction factors, the limits of detection were between 0.012 and 0.061 μg/L, relative standard deviations for precision in terms of intra- and inter-day assay variability ranged from 1.9 to 9.8%. The introduced approach was successfully applied to simultaneously quantify the contents of five analytes in real fruit juices with satisfying fortified recoveries (80.1-116%). The obtained results well demonstrate the promising potential of the developed method in the highly sensitive quantification of trace phenolic acids in complex samples.

Magnetism-assisted in-tube solid phase microextraction for the on-line chromium speciation in environmental water and soil samples

In the present study, a new method for chromium speciation was proposed by on-line coupling of magnetism-assisted in-tube solid phase microextraction (MA/IT-SPME) with high-performance liquid chromatography-diode array detector (HPLC-DAD). Firstly, Cr(III) and Cr(VI) were coordinated with ammonium pyrrolidinedithiocarbamate (APD) to form Cr(III)/APD and Cr(VI)/APD complexes, separately. After that, a microextraction column based on porous monolith doped with magnetic nanoparticles was in situ fabricated in a capillary. The microextraction column was twined with a magnetic coil which was employed to engender changeable magnetic fields during extraction period. Various main factors influencing the extraction performance were inspected in detail. Results well indicated that the implementation of the magnetic field could assist the enhancement of extraction efficiency for Cr(III)/APD (80.4%) and Cr(VI)/APD (86.2%) complexes. Under the optimized parameters, the limits of detection for Cr(III) and Cr(VI) in water sample were 0.0059 μg/L and 0.0020 μg/L, respectively, and the corresponding values in soil sample were 0.47 μg/kg and 0.057 μg/kg, separately. The enrichment factors were 59 and 72 for Cr(III) and Cr(VI), respectively. The successful quantification of Cr(III) and Cr(VI) at trace levels in environmental water and soil samples well demonstrated the reliability and practicality of the proposed on-line approach for chromium speciation.

Fabrication of Functional Groups-Rich Monolith for Magnetic Field-Assisted In-Tube Solid Phase Microextraction of Inorganic Selenium Species in Water Samples Followed by Online Chromatographic Determination

Efficient separation and enrichment is a crucial step in the analysis of Se(IV) and Se(VI). In the present study, for the first time, online monolith-based magnetic field-assisted in-tube solid phase microextraction (MFA/IT-SPME) was applied to capture inorganic selenium species in water samples. In this connection, porous monolith mingled with magnetic nanoparticles was synthesized in silica capillary and employed as microextraction column (MEC) of MFA/IT-SPME. After that, a magnetic coil utilized to perform variable magnetic fields in adsorption and desorption steps was twined on the MEC. Se(IV) was coordinated with o -phenylenediamine to form coordination compound which was infused to the MEC to be captured. Results evidenced that application of magnetic field during extraction procedure assisted the capture of Se(IV)-OPA complex with the enhancement of extraction efficiency from 83% to 97%. Under the optimized conditions, MFA/IT-SPME was online combined with HPLC equipped with diode array detector (DAD) to perform quantification of Se(IV) and Se(VI) in environmental water samples. Total inorganic Se was quantified after pre-reduction of Se(VI) to Se(IV) prior to applying established approach, and subtraction method was adopted to calculate Se(VI) and Se(IV) contents. The limit of detection for Se(IV) was as low as 0.012 μg/L. Reliability of suggested method was investigated by assaying Se(IV) and Se(VI) species in real-life waters with satisfactory recoveries (81.1%-116%) and repeatability (RSDs below 9%).

Development of magnetism-reinforced in-tube solid phase microextraction combined with HPLC for the sensitive quantification of cobalt(II) and nickel(II) in environmental waters

Magnetism-reinforced in-tube solid phase microextraction (MR/IT-SPME) based on porous monolith combined with HPLC/DAD was developed for the sensitive and reliable analysis of cobalt(II) and nickel(II) in environmental waters. Co(II) and Ni(II) were coordinated with 4-(2-pyridylazo)resorcinol (PAR) to form Co-PAR and Ni-PAR complexes. Monolith-based capillary microextraction column mingled with Fe3O4 nanoparticles (MCN) was tailored according to the chemical properties of Co-PAR and Ni-PAR complexes. To reinforce the extraction performance, a magnetic coil which could produce variable magnetic fields during extraction period was twined round the MCN to set up the MR/IT-SPME system for the efficient extraction of Co-PAR and Ni-PAR complexes. Various parameters influencing the extraction performance were inspected to achieve the most appropriate conditions. Results well proved that the application of magnetic field enhanced the extraction efficiencies of the metal complexes obviously (from 48.4 to 52.2% to 70.9–91.7%). Combing with HPLC with diode array detection (HPLC/DAD), limits of detection for Co(II) and Ni(II) were as low as 0.060–0.14 μg/L. The suggested MR/IT-SPME-HPLC/DAD approach was successfully applied to measure low concentrations of Co(II) and Ni(II) in different environmental water samples. The recoveries with different fortified levels were in the range of 81.4–118%, and the RSDs for reproducibility varied from 2.0% to 9.7%. Based on the satisfying results, the introduced approach can be used for routine monitoring of Co(II) and Ni(II) in various aqueous environmental samples.

Simultaneous enrichment and analysis of benzimidazole by in-tube SPME-MS based on poly (3-Acrylamidophenylboronic acid-co-divinylbenzene-co-N,N′-methylenebisacrylamide) monolithic column

In this work, a sensitive, rapid, and matrix effect-free method for online simultaneous detection of benzimidazoles in animal products by in-tube solid-phase microextraction coupled with mass spectrometry (in-tube SPME-MS) was investigated. Herein, according to the chemical structures properites of the analyte benzimidazoles, poly (3-Acrylamidophenylboronic acid-co-divinylbenzene-co-N,N′-Methylenebisacryladmide) [poly (AAPBA-co-DVB-co-MBAA)] microextraction column was prepared, and severs as the extraction and enrichment medium (in-tube SPME) via hydrophobic, B–N coordination, π-π, and hydrogen bonding interactions with the benzimidazoles. The monolithic column was optimized and characterized, showing satisfactory permeability and extraction capacity in range of 514–1000 μg mL−1 for the benzimidazoles. The important parameters of the in-tube SPME-MS system experimental condition were systematically optimized to achieve the maximal extraction efficiency. Under the optimized condition, the MS intensity of benzimidazoles measured by in-tube SPME-MS is more significant, cleaner, and has a better signal-to-noise ratio than the mass intensity measured by direct MS method. Good linearity was obtained with correlation coefficients between 0.9915 and 0.9990, and the detection limits (S/N = 3) of the benzimidazoles were between 0.55 and 0.91 ng g−1. Recoveries in the range of 72.5%–92.4% were obtained for the benzimidazoles in pork and chicken in three spiked concentration levels, with satisfactory relative standard deviations (n = 4) that lower than 7.5%. The developed in-tube SPME-MS method based on the poly (AAPBA-co-DVB-co-MBAA) column was successfully used to sensitively determine trace benzimidazoles in animal products without interference peaks, indicating that it is promising for the analysis of benzimidazoles in practical samples that requiring minimal sample pre-treatment and no chromatographic separation.

Evaluation of Two Fully Automated Setups for Mycotoxin Analysis Based on Online Extraction-Liquid Chromatography-Tandem Mass Spectrometry.

Mycotoxins are secondary metabolites of fungi species widely known for their potentially toxic effects on human health. Considering their frequent presence in crops and their processed food, monitoring them on food-based matrices is now an important topic. Within such a context, the sample preparation step is usually mandatory before the chromatographic analysis, due to the complexity of matrices such as nuts, cereals, beverages, and others. For these reasons, we herein present the evaluation of two greener setups, based on the automation and miniaturization of the sample preparation step for mycotoxin analysis in different beverages. Firstly, we describe an analytical method based on a multidimensional assembly, coupling a lab-made microextraction column (508 µm i.d. × 100 mm) to a UPLC–MS/MS for the analysis of ochratoxin A in beverages. This configuration used a synthesized sorbent phase containing C18-functionalized graphene–silica particles, which exhibited excellent extraction performance, as well as being reusable and cheaper than commercially available extractive phases. Sequentially, a second setup, based on a multidimensional capillary LC coupled to MS/MS, was assessed for the same purpose. In this case, a graphene oxide-based capillary extraction column (254 µm i.d. × 200 mm) was used as the first dimension, while a C18 analytical capillary column performed the mycotoxin separation in beverages. Although this second one has similarities with the first, we focused mainly on the benefits related to the link between a miniaturized/automated sample preparation device with a capillary LC–MS/MS system, which made our analysis greener. Additionally, the chromatographic efficiency could even be enhanced.

On-line microcolumn-based dynamic leaching method for investigation of lead bioaccessibility in shooting range soils

In this work, a miniaturized flow-through leaching test is presented for rapid screening of potential chemical extractants to explore the bioaccessibility of lead (Pb) in contaminated shooting range soils in Valkeala, Finland. The method combines the versatility of microcolumn-based extraction methods with on-line inductively coupled plasma optical emission spectrometry (ICP OES) analysis for expedient assessment of the magnitude of the bioaccessible pools and the leaching kinetics of lead from polluted soils under variable physicochemical scenarios. Acids and salt solutions were studied as potential extractants. The efficiency of the extractants relative to the initial total amount of lead in the soil sample (509 ± 21 mg/kg) were found to increase in the following order: 0.11 M acetic acid (55%) < 1 M MgCl2 (58%) < 0.1 M NH2OH·HCl (61%) < 0.1 M citric acid (93%) < 0.1 M HCl (96%). The proposed on-line microcolumn-based method was further explored for implementation of the modified BCR (now termed Standards, Measurements and Testing Programme, SM&T) sequential extraction procedure to avail the information about different fractions available in the solid sample, and validated by mass balance calculations. The equivalent sequential procedure in a batch format was then studied and compared against the on-line microcolumn extraction method.The on-line dynamic extraction system presented in this work accepts a substantial amount of sample (2.5 g) as compared to previous flow-through mini-column setups (generally accommodating < 0.25 g of sample), thus maintaining sample representativeness and fostering comprehension of the extraction patterns for non-homogenous soil materials. The use of cotton buds and Teflon membranes and holders in the microcolumn setup facilitates the repeatable flow-through leaching of trace elements and restrict formation of preferential channels. Monitoring of the leachable trace elements in real time delivers detailed insight into the ongoing extraction process and provides a time-saving assessment of potential chemical extractants.

Preparation and application of immunoaffinity in-tube solid phase microextraction column with oriented antibody-immobilized porous layer open tubular capillary for high sensitive quantification of serum extracellular domain of human epidermal growth factor receptor 2 levels

Human epidermal growth factor receptor 2 (HER2) gene expresses a transmembrane glycoprotein that is over-expressed in 15–30% breast, 3% lung, and other several digestive cancers. So HER2 is a good biomarker for tumor diagnostic and treatment monitoring. Clinically, detection of HER2 often employs invasive approaches with tissue samples, which at large extent limit its universal application. Shedding of the extracellular domain (ECD) of the HER2 (HER2-ECD) into the circulation has led to the development of a serum test of HER2-ECD as an additional approach to probe the HER2 overexpression. However, few methods were developed due to the high sensitivity required by the serum HER2-ECD determination. In this work, we prepared a novel immunoaffinity in-tube solid phase microextraction (IT-SPME) sorbent for selective enrichment of HER2-ECD. Two clinical available monoclonal antibodies against to HER2, trastuzumab and pertuzumab, were selected as immunoaffinity ligands. Porous layer open tubular capillary with oriented antibody immobilization were fabricated and systematically optimized to afford a higher extraction capacity. The capacity was reached to 120.4 μg/m, which is more than 1000 times higher than that obtained by a common method (directly antibody immobilization on a naked capillary). After sample extraction and enrichment by the IT-SPME, the eluent were determined by a particle-enhanced turbidimetric immunoassay (PETIA). Sensitive quantification of HER2-ECD by the PETIA was thereby accomplished. HER2-ECD concentrations in 82 clinical serum samples were determined by the developed IT-SPME/PETIA method, and the results were well-correlated with that by the clinical used chemiluminescence immunoassay (CLIA). Besides, the IT-SPME/PETIA method was found providing 5 times higher sensitivity than the CLIA, and 500 times higher than the PETIA without IT-SPME. The results indicate that the developed method is suitable for high-sensitive quantification of HER2-ECD in clinical samples.

Porous monolith-based magnetism-reinforced in-tube solid phase microextraction of sulfonylurea herbicides in water and soil samples

In the present study, porous monolith-based magnetism-reinforced in-tube solid phase microextraction (MB-MR/IT-SPME) was first introduced to concentrate sulfonylurea herbicides (SUHs). To realize the effective capture of SUHs, a monolithic capillary microextraction column (MCMC) based on poly (vinylimidazole-co-ethylene dimethacrylate) polymer doped with Fe3O4 magnetic nanoparticles was in-situ synthesized in the first step. After that, the MCMC was twined with a magnetic coil which was employed to carry out variable magnetic field during adsorption and desorption procedure. Various important parameters that affecting the extraction performance were inspected in detailed. Results well indicated that exertion of magnetic field in the whole extraction procedure was in favor of the capture and release of the studied SUHs, with the extraction efficiencies increased from 36.8–58.1% to 82.6–94.5%. At the same time, the proposed MB-MR/IT-SPME was online combined to HPLC with diode array detection (HPLC/DAD) to quantify trace levels of SUHs in water and soil samples. The limits of detection (S/N = 3) for water and soil samples were in the ranges of 0.030–0.15 μg/L and 0.30–1.5 μg/kg, respectively. The relative standard deviations (RSDs) for intra- and inter-day variability were both less than 10%. Finally, the introduced approach was successfully applied to monitor the low contents of studied SUHs in environmental water and soil samples. Satisfying fortified recovery and precision were achieved.

Magnetism-reinforced in-tube solid phase microextraction for the online determination of trace heavy metal ions in complex samples

For the first time, a convenient, online couplable, sensitive and environmentally friendly sample pretreatment method, namely, magnetism-reinforced in-tube solid phase microextraction (MR/IT-SPME) was proposed to effectively enrich heavy metal ions (HMIs). Monolithic capillary microextraction column embedded modified Fe3O4 magnetic nanoparticles (MCEN) was conveniently synthesized and employed as the microextraction column of MR/IT-SPME. Subsequently, the MCEN was put into a magnetic coil which was utilized to exert variable magnetic field during extraction procedure. Three HMIs, including Cu(II), Co(II) and Hg(II), were selected as studied ions and reacted with chelating agent sodium diethyldithiocarbamatetrihydrate to form metallic coordination compounds. The complexes were infused to the MCEN to perform the MR/IT-SPME extraction and then online determined by high-performance liquid chromatography equipped with diode array detection (HPLC-DAD). A series of key parameters affecting the extraction performance were investigated in detail. Results revealed that the exertion of magnetic field in adsorption and desorption steps favored the adsorption and release of the coordination compounds, with the extraction efficiencies enhanced from 47-65% to 67–89%. Finally, the developed online MR/IT-SPME-HPLC-DAD approach was successfully applied to determine studied HMIs in environmental water and seafood samples. The confirmatory experiments further evidenced the reliability and feasibility of the introduced approach for the analysis of trace HMIs in complex samples.

Ultrasonic Nebulization-Dispersive Solid-Phase-Monolithic Microcolumn Extraction Coupled with HPLC–MS/MS for Analyzing Sex Steroids in Lotion Samples

An ultrasonic nebulization-dispersive solid-phase-monolithic microcolumn extraction method coupled with high-performance liquid chromatography–mass spectrometry was developed and applied for the extraction and analysis of 15 sex steroids in lotion samples. In this method, the analytes were microextracted from a liquid phase to a dispersive solid phase, and then, a monolithic microcolumn was prepared with these dispersive solid-phase particles using our device. In this way, a more efficient extraction method was developed. Several experimental parameters, including the extraction sorbent, amount of the adsorbent, extraction time, and extraction temperature, were optimized. Calibration curves for steroid concentrations ranging from 0.11 to 1461.00 ng mL−1 were obtained for analyzing the sex steroids. The recoveries in the determination of the sex steroids were between 53.19 and 96.99%, and the relative standard deviations ranged from 2.58 to 7.52%. These results indicated that the proposed method is a fast, sensitive, low-cost, and highly efficient extraction and enrichment technique for the analysis of nonvolatile analytes in liquid samples.

Complementary assessment of As, Cu and Zn environmental availability in a stabilised contaminated soil using large-bore column leaching, automatic microcolumn extraction and DGT analysis

Soil pollution with trace elements is a concerning issue worldwide. Monitoring of soil pollution and remediation protocols need still from valid complementary analytical approaches able to detect changes in speciation and lability of metals in soils (e.g. stabilization or mobility). In this work, we compare three different analytical approaches to assess potential changes in environmental availability of Cu, As and Zn in a Mediterranean polluted soil that was amended with different combinations of iron sulphate and alkaline paper sludge waste. The studied methods were: (i) a standard large-bore flow-through column system (macrocolumn), (ii) an automatic dynamic flow-through microcolumn extraction system, and (iii) the diffusive gradients in thin gels technique (DGT). The three analytical approaches tested showed immobilization of Zn and Cu in contaminated mine soils after co-application of paper sludge and iron sulphate, but they differ quantitatively in terms of As mobility. Interconversion between oxidation states of inorganic As is observed to occur to a larger extent in macrocolumn. Because this may only occur in very specific Mediterranean scenarios (i.e. organic matter application to intermittently flooded mine soils), macrocolumn extraction procedures might not appropriately mimic the environmental availability of As in soils with organic amendments (e.g., paper sludge waste). Microcolumn leaching is the fastest screening tool to ascertain the efficiency of chemical amendments, but DGT is a good alternative with less technical demands.