Simultaneous Preconcentration Research Articles

Preparation and application of nano petal-shaped covalent organic frameworks modified polystyrene-divinylbenzene- glycidylmethacrylate microspheres for the extraction of illicit drugs from wastewater

A novel nano petal-shaped covalent organic frameworks modified magnetic polystyrene-divinylbenzene-glycidylmethacrylate (NP-COF@Mag-PS/DVB/GMA) microsphere has been synthesized. It is a perfect combination of high productivity of PS/DVB/GMA microspheres and excellent enrichment efficiency of COF particles, and the excellent properties of NP-COF@Mag-PS/DVB/GMA microspheres are characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) and X-ray photoelectron spectroscopy (XPS). The sorbent can extract illicit drugs via the reverse-phase interactions provided by benzene ring on the polymer backbone and the hydrogen bonding interactions provided by functional group (-NH-) on the COF particles. Based on using NP-COF@Mag-PS/DVB/GMA as sorbents, an easiness-to-handle of magnetic dispersive solid phase extraction (Mag-dSPE) procedure is proposed for the simultaneous preconcentration of 12 illicit drugs from wastewater. The obtained results show high extraction efficiency of NP-COF@Mag-PS/DVB/GMA to illicit drugs with recoveries between 81.6 and 116%. Furthermore, a liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS) method for the determination of 12 illicit drugs from wastewater at sub-ppt levels has been proposed and validated with the pretreatment of samples by Mag-dSPE. The limits of quantification (LOQs) for the 12 illicit drugs are between 0.40 and 4.90 ng/L. Validation results on linearity, specificity, trueness and precision, as well as on application to the analysis of 12 illicit drugs in ten real samples demonstrate the applicability to environment monitoring analysis.

Ultrasound-assisted deep eutectic solvent-based liquid–liquid microextraction for simultaneous determination of Ni (II) and Zn (II) in food samples

A new approach was developed for the simultaneous pre-concentration and determination of Ni (II) and Zn (II) in food samples. This method is based on ultrasound-assisted liquid–liquid micro extraction using hydrophobic deep eutectic solvent (DES) and 1,10-phenanthroline as chelating agent. The effect of several parameters, such as pH, selection and volume of DES, amount of chelating agent, time of sonication and centrifugation, was studied. Under optimized conditions, the developed procedure offered exceptional sensitivity and linearity. The limit of detection was approximately 0.029 µg/Kg and 1.5 µg/Kg for Ni (II) and Zn (II), respectively. The proposed method was applied for the pre-concentration and determination of Ni (II) and Zn (II) in hydrogenated edible oils, fishes, and milk samples. The results of this study were compared with reported methods in the literature revealing its advantages.

Simultaneous preconcentration and pre-column derivatization for rapid analysis of nitrilotriacetic acid in environmental waters by high performance liquid chromatography

A simplified sample pretreatment procedure was developed for quantitative measurement of nitrilotriacetic acid (NTA) in environmental water. On the basis of coordination capacity between NTA and metal ions, aluminum-based metal organic framework (MOF, MIL-53(Al)) was adopted for the adsorption of NTA, followed by stripping with copper sulfate as the eluent. The adsorbed NTA was converted into Cu-NTA during the desorption process, which facilitated the ensuing measurement by high performance liquid chromatography (HPLC). A linear range within 0.10 - 10 mg L−1 was achieved, along with a limit of detection (LOD, S/N=3, n=7) of 0.03 mg L−1 and an enrichment factor of 10.4. The developed method was validated by the analysis of sea water, influent of wastewater treatment plant and industrial wastewater, with satisfactory recoveries (90.2 - 91.1%) obtained.

A magnetic covalent organic framework as selective adsorbent for preconcentration of multi strobilurin fungicides in foods

A new method that utilizes a magnetic covalent organic framework (Fe3O4@BTA-TAPM) as a selective solid-phase extraction adsorbent has been developed for the simultaneous preconcentration of trace eleven kinds of strobilurin fungicides (SFs) in foods combined with ultra-high performance liquid chromatography-tandem mass spectrometry. The preconcentration conditions were optimized, including the adsorbent amount, extraction time, pH value, shaking time, elution solvent, desorption time and the interference ions. The maximum adsorption capacity of the adsorbent was ranging from 42.84 mg g−1 to 54.18 mg g−1 for eleven SFs. The low limits of detection were 0.003–0.072 μg kg−1. The recoveries of eleven SFs spiked at levels of 0.25–1000 μg kg−1 ranged from 80.2% to 109.3%, and the relative standard deviations were <6.8% (n = 3). The utility of the adsorbent was demonstrated to determine traces SFs in four different samples.

Determination of Ultratrace Levels of Cobalt (II) and Chromium (III) by Magnetic Dispersive Solid-Phase Extraction (SPE) Using Urea-Formaldehyde Polymer/Magnetite Nanoparticles with Flame Atomic Absorption Spectrometry (FAAS)

A fast, selective and sensitive magnetic dispersive solid-phase extraction (SPE) method is presented for the first time for simultaneous preconcentration of ultra-trace levels of cobalt (II) and chromium (III) before their quantification by flame atomic absorption spectrometry (FAAS). Urea-formaldehyde polymer/magnetite nanoparticles (UFP/MNPs) were used as adsorbents. The prepared nano-adsorbent was assessed by x-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). The excellent magnetic properties of the prepared adsorbent promote rapid isolation of the analytes. A comprehensive study was performed on the extraction conditions and optimal levels of effective parameters were determined. Using the optimum conditions, linear dynamic ranges of 0.8–150 and 0.3-80 μg L−1 were obtained for cobalt (II) and chromium (III), respectively. The limits of detection were 0.2 and 0.09 µg L−1 for cobalt (II) and chromium (III). Intra-day and inter-day relative standard deviations (RSDs) were 3.8% and 5.7%, respectively. Adsorption isotherms were investigated and high adsorption capacities were obtained for the metal ions. The developed method managed to extract and quantify the analytes from unspiked and spiked environmental water samples from the Caspian Sea, Ardabil Balighli Chay River, and Ardabil tap water. The recoveries and relative standard deviations for the samples were from 98.2 to 103% and 0.2 to 5.7%, respectively. The results were validated by comparison with inductively coupled plasma – optical emission spectroscopy (ICP-OES) measurements.

Synthesis of green nano sorbents for simultaneous preconcentration and recovery of heavy metals from water

The wastewater containing Cd, Co, Fe, Cu, Cr, Mn, Ni and Pb ions are as trace metal pollutants. Water pollution caused by increment in industrialization and overpopulation reveals a major threat to human health. Adsorption is recognized as the effective and optimum method to remove water contaminations. The amorphous and porous form of silicon dioxide is silica gel widely used as an adsorbent. It can absorb moisture with traces of the target heavy metal ions. This research elaborates a simplistic, and reliable preconcentration column method highly developed for the determination of Cd2+, Fe3+, Co2+, Cr3+, Cu2+, Mn2+, Pb2+ and Ni2+ ions in model solutions and real water samples by flame atomic absorption spectrometry (FAAS). The proposed operation depends on the retention of the target ions from buffered model solutions on a silica gel filled up a column modified with vanadium(V) oxide sorbent followed by their desorption. SiO2/V2O5 is an efficient adsorbent due to its low cost, eco-friendly and high availability. The adsorbent morphological and interfacial physicochemical characterization was done using scanning electron microscopy, and Fourier transmission infrared spectroscopy, respectively. The 2.92 value achieved for the point of zero charges supports the experimentation for the heavy metal efficient adsorption. Quantitative recoveries were achieved at pH 10 with 50 mg of SiO2/V2O5 mass and adsorption capacity ranged from 28.96 μmol/g (Pb) to 214.86 μmol/g (Fe) with 1114.79 μmol/g in total. Simultaneous preconcentration effect was determined by the interference cations on the sorbent. The LOD varies from 8.42 to 50.56 μg/L and LOQ is achieved from 20.06 to 72.41 μg/L of 15 blank solutions. The developed preconcentration procedure was adequately implemented for the simultaneous analysis of eight metallic ions content in local river samples. The developed vanadium(V) oxide incorporated with silica gel is practicable as an economical and effective adsorbent to eliminate metallic ions from a liquid solution.

Application of electrocolorimetric extraction for the determination of Ni(II) ions in chocolate samples: A green methodology for food analysis

This study developed an electrocolorimetric extraction technique as a simple, rapid, and green method for the simultaneous preconcentration and determination of Ni(II) in chocolate samples. The system was designed using an agarose gel (3% w/v) solution containing 10% v/v 80 mM dimethylglyoxime (DMG) and 10% v/v 0.03 M ammonia as colorimetric reagents to determine Ni(II) ions. When voltage was applied to the system, Ni(II) ions were extracted from the donor solution into the gel and formed Ni-DMG complexes with a pink color. Under the optimal conditions, a good linear range was obtained from 30 to 750 µg L−1 (R2 > 0.998) with a detection limit of 1 µg L−1. Inter- and intra-assay results showing relative standard deviations were less than 2.6% and 1.9%, respectively. Our developed method was applied to determine Ni(II) in chocolate samples. The results were in agreement with those obtained using ICP–OES.

Simultaneous on-line preconcentration and determination of toxic elements in rice and rice-based products by SPE–ICP–MS: Multiple response optimization

Simultaneous preconcentration of five toxic elements (Cd, Hg, Mn, Pb, and Sb) was carried out using a hyphenated system by on-line coupling of flow injection (FI), solid phase extraction (SPE) and inductively coupled plasma mass spectrometry (ICP–MS). The analytes were simultaneously preconcentrated on a microcolumn filled with oxidized multiwalled carbon nanotubes (ox-MWCNTs). During the method development, SPE conditions were optimized using a chemometric approach with experimental design and desirability function by multi-response surface methodology. An enrichment factor of 104 was obtained when 50 mL of sample were passed through the microcolumn. After optimizing the FI–SPE–ICP–MS system, detection limits were calculated varying from 0.8 ng L−1 for Mn to 0.09 μg L−1 for Hg. The relative standard deviations (RSD) for all elements were < 5%. For checking accuracy two standard reference materials NIST1568b (Rice Flour) and NIST 1643f (Trace Elements in Water) were analyzed and results were in good agreement with certified values. The proposed method was successfully applied to the determination of Cd, Hg, Mn, Pb and Sb in real samples of rice and rice-based products. The concentration of the analytes spanned in the range (ng g−1): Cd, 0.18–23.5; Hg, <4.6-6.0; Mn, <0.04–744; Pb, <0.16–462 and Sb, 5.9–47.

Simultaneous preconcentration and fluorescence detection of ATP by a hybrid nanocomposite of magnetic nanoparticles incorporated in mixed metal hydroxide.

A new approach for increasing the sensitivity of adenosine triphosphate (ATP) detection was demonstrated. The assay was based on the synergetic function of a hybrid nanocomposite (MNPs@MMH) composed of magnetic nanoparticles (MNPs) incorporated in a mixed metal hydroxide (MMH). MNPs@MMH can be utilized as an efficient green extractant and peroxidase catalyst. The trace level of ATP in the sample solution was first extracted by the MNPs@MMH hybrid nanocomposite through the ion exchange properties of MMH and adsorbed on the surface of the MNPs@MMH. The concentration of ATP was related to the fluorescence intensity of 2,3-diaminophenazine (DAP) generated from peroxidase-like activity of the MNPs in the presence of H2O2 and o-phenylenediamine (OPD). In the presence of ATP, the active surface of the MNPs was diminished, and the amount of DAP generated was reduced. Thus, the concentration of ATP was related to the degree of fluorescence decrease compared to the fluorescence intensity of the system without ATP. Based on the proposed strategy, a highly sensitive assay for ATP was achieved. This assay exhibited good selectivity for detection of ATP over derivatives and other common anions. The proposed assay allowed the detection of ATP in a concentration range of 2.5-20 μM with a detection limit of 0.41 μM.

Investigation of the performance of cross-linked poly(acrylic acid) and poly(methacrylic acid) as efficient adsorbents in SPE columns for simultaneous preconcentration of tricyclic antidepressants in water samples.

A solid phase extraction-based (SPE) procedure for simultaneous preconcentration of five tricyclic antidepressants (TCAs), amitriptyline hydrochloride (AMT), nortriptyline hydrochloride (NOR), doxepin hydrochloride (DOX), imipramine hydrochloride (IMI), and clomipramine hydrochloride (CLO) from water samples with determination by HPLC-DAD is proposed. Polymers were characterized by FT-IR, SEM, and thermogravimetric analysis. SPE-based methods were carried out by the preconcentration of 320.0 mL of TCAs at pH 7.0 (buffered with 0.01 mol L-1 phosphate buffer) through 70.0 mg of adsorbent packed into a SPE cartridge, followed by elution with 1.0 mL of ACN : MeOH : acetic acid solution (45 : 45 : 10% v/v). Higher preconcentration factors were obtained ranging from 117.9 to 372.2 and 207.1 to 396.1 by using poly(MAA-co-EGDMA) and poly(AA-co-EGDMA), respectively, yielding lower limits of detection (0.03 to 0.12 μg L-1) and (0.03 to 0.15 μg L-1). These outcomes show satisfactory detectability of SPE-based methods, with slightly better performance using poly(MAA-co-EGDMA). On the other hand, poly(AA-co-EGDMA) was able to preconcentrate TCAs in the presence of humic acid (7.0 mg L-1) without interference. The precision of methods assessed as RSD (%) was very similar, ranging from 1.7% to 16.3% for poly(MAA-co-EGDMA) and 1.7% to 13.4% for poly(AA-co-EGDMA). SPE cartridges packed with the polymers showed high reusability (52 cycles of preconcentration and elution) without losing adsorption efficiency. The methods were applied to determine TCAs in tap, lake, and stream water samples and the accuracy was attested by addition and recovery tests (86.7-116.0%), with determined nortriptyline ranging from 0.48 to 0.52 μg L-1 in lake water samples.

Simultaneous preconcentration and determination of sulfonamide antibiotics in milk and yoghurt by dynamic pH junction focusing coupled with capillary electrophoresis

A dynamic pH junction was used in capillary electrophoresis (CE-DAD) to on-line preconcentrate, separate, and determine trace amounts of sulfonamide antibiotics (SAs) in milk and yoghurt samples in this study. A sample matrix with 0.15% acetic acid and 10% methanol (MeOH) at a pH of 4.0, and a background electrolyte (BGE) that contained 35 mM sodium citrate with 10% MeOH at a pH of 8.5, and an acidic barrage of 0.4% acetic acid with 10% MeOH at a pH of 2.5 were utilised to achieve a stacking effect for SAs through a dynamic pH junction. Under optimised conditions, the proposed preconcentration method showed good linearity (30–500 ng/mL, r2 ≥ 0.9940), low limits of detection (LODs) of 4.1–6.3 ng/mL, and acceptable analytes recovery (81.2–106.9%) with relative standard deviations (RSDs) within 5.3–13.7 (n = 9). The limits of quantification (LOQs) were below the maximum residue limit approved by the European Union (EU) in this type of matrices. Sensitivity enhancement factors of up to 129 were reached with the optimised dynamic pH junction using CE with a diode array detector (DAD). The method was used to determine SAs in fresh milk, low-fat milk, full-cream milk, and yoghurt samples.

Simultaneous preconcentration of both polar and non-polar Q-markers of flavonoids in traditional Chinese medicine by reverse micellar floating solidification liquid-phase microextraction

A reverse micellar floating solidification liquid-phase microextraction was proposed for simultaneous preconcentration and determination of both polar (scutellarin, baicalin) and non-polar (scutellarein, luteolin, apigenin, wogonin) quality-markers of flavonoids in traditional Chinese medicine coupled with high performance liquid chromatography-ultraviolet detection. In this work, the reverse micelle of Aliquat 336/dodecanol as the extractant was used to enrich target analytes. The synthesis of the reverse micellar extractant was investigated, and its microstructure was characterized by fluorescence microscope and transmission electron microscope. The variables affecting the experimental procedure, including reverse micelle volume, sample phase pH, salt amount, extraction temperature, extraction time and stirring rate were investigated and optimized. Under the optimum conditions, enrichment factors between 155 and 329 for the target analytes, satisfactory linear ranges (r ≥ 0.9983), low detection limits (0.05–0.25 ng mL−1), acceptable precisions (relative standard deviations of 0.2–8.9%) and accuracies (recoveries of 87.2–108.5%) were obtained. The extraction mechanism based on reverse micelle was explored and elucidated. The characteristics of the proposed method were summarized by comparison with others. The developed approach was successfully applied for the extraction and concentration of six quality-markers of flavonoids with different polarities from a traditional Chinese medicinal herb of Scutellariae Barbatae Herba.

Determination of lanthanide and actinide elements by energy dispersive x-ray fluorescence spectrometry applying DLLME preconcentration and dried spot

This work describes an analytical procedure to determination of trace amount of lanthanide and actinide chemistry elements (LAEs) in water samples by energy dispersive x-ray fluorescence spectrometry (EDXRF) with the prepare of the samples using simultaneous preconcentration procedure based on the dispersive liquid-liquid microextraction (DLLME). Critical study of the analytical procedure occurred the following way: ions of Eu, Er, Ho, Th, U and Yb presents in 5.0 mL of aqueous sample have been complexed with 2-(5-bromo-2-pyridylazo)-5-(diethylamino)-phenol (Br-PADAP) in a mixture contained solvents (disperser and extractant). After centrifugation, 30 μL of the sedimented organic phase has been removed and deposited on membrane disk and submitted to EDXRF analysis. The optimization step was performed by: i) screening factor with mixture design for the disperser solvent (acetone, acetonitrile and ethanol) and extractant solvent (carbon tetrachloride, trichlorethylene and 1,2-dichloroethane); ii) Box-Behnken design for the independents variables: pH, Br-PADAP concentration, volume of disperser solvent and volume of extractant solvent. The optimized conditions were: 500 μL of disperser solvent (ethanol), 60 μL extractant solvent (carbon tetrachloride and trichlorethylene, 1: 1 ratio), Br-PADAP 1.8 × 10−5 mol L−1 and pH 8.0. In these conditions, the procedure allows the determination of Eu, Ho, Er, Yb, Th and U with quantification limits of 10.5; 8.6; 4.3; 7.0; 6.6 and 1.1 μg L−1, respectively; preconcentration factor between 18 and 74, and precision (RSD%) below that 6%. Salting out effect, presence of other ions, and additions/recoveries of analytes in real samples was verified and the recovery values were between of 90 to 107%. Analytical method has been applied in waters samples and groundwater from uranium mining region.

Fe3O4@PDA@PANI core–shell nanocomposites as a new adsorbent for simultaneous preconcentration of Tartrazine and Sunset Yellow by ultrasonic-assisted dispersive micro solid-phase extraction

In this research, novel magnetic Fe3O4@PDA@PANI core–shell nanoparticles were designed and fabricated as an efficient adsorbent in the service of ultrasound-assisted dispersive micro-solid phase extraction for simultaneous preconcentration of Sunset Yellow (SY) and Tartrazine (Tar) before UV–Vis spectrophotometric detection. This adsorbent was fully characterized by Fourier Transform Infrared (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Energy Dispersive X-ray (EDX) analysis. To overcome the spectral overlapping of SY and Tar dyes, the derivative spectrophotometric method was successfully used for the simultaneous detection of dyes in their binary solutions. The operating parameters affecting preconcentration efficiency and spectrophotometric determination were optimized. Under optimal conditions, the limit of detections (LOD) was obtained 0.2 and 0.5 ng mL−1 for SY and Tar, respectively. The adsorption capacity and reusability of core–shell nanoparticles were significant. The satisfactory results of analysis of a few real samples indicate that the method is very favored in the analysis of various complex matrices.

Simultaneous determination of five opium alkaloids in underground waters using molecularly imprinted polymer-modified magnetic nanoparticle based dispersive micro-solid phase extraction followed by high performance liquid chromatography

ABSTRACT In this work, we present a fast, simple and selective method for the extraction/preconcentration and determination of five opium alkaloids. This method is based on the combination of dispersive solid phase extraction with magnetic molecularly imprinted polymers (MMIP) and determination via high performance liquid chromatography. The surface modified Fe3O4 nanoparticles were synthesised in-situ, from a co-precipitation method by addition of a mixture of the methacrylic acid and ammonia to a mixture of Fe2+/Fe3+ under nitrogen atmosphere. MMIP was prepared from surface modified nanoparticles in the presence of ethylene glycol dimethyl acrylate as cross-linker and azobisisobutyronitrile as initiator and template molecule under reflux in acetonitrile. MMIPs for five natural occurring opium alkaloids, including morphine (MO), codeine (CO), thebaine (TE), noscapine (NO) and papaverine (PA) were prepared in the same manner. Structural characterisation and elucidation of both synthesised nanoprticles were performed by Fourier transform-infrared spectroscopy, scanning electron microscopy. X-ray diffraction and vibrating sample magnetometry. A precise chromatographic method was developed and coupled with extraction with MMIP nanoparticles for simultaneous preconcentration and determination of above-mentioned alkaloids in underground water samples. The limit of detection obtained 0.007, 0.007, 0.004, 0.003, 0.003 mg L−1 for MO, CO, TE, NO and PA, respectively and recoveries were about 97–102%. Linear dynamic range and relative standard deviation were 0.03–100 mg L−1 and less than 1.5% for each analyte.

Magnetic porous carbon nanocomposite derived from cobalt based-metal-organic framework for extraction and determination of homo and hetero-polycyclic aromatic hydrocarbons

Herein, a novel magnetic porous carbon nanocomposite derived from a cobalt based-metal-organic framework was synthesized and evaluated for simultaneous preconcentration of homo and hetero-polycyclic aromatic hydrocarbons. Briefly, magnetite nanoparticles (MNPs) were synthesized and then were coated with a metal-organic framework layer. Finally, the magnetic nanocomposite was carbonized under an inert atmosphere to obtain the magnetic porous carbon (MPC). Various characterization techniques such as FT-IR spectroscopy, transmission and scanning electron microcopies, vibrating sample magnetometry, and X-ray diffraction were employed. Applicability of the MPC was explored using benzothiophene, dibenzothiophene, 9,10-dimethylanthracene, and benz[α]anthracene as the model analytes. Limits of detection and linearities were achieved in the range of 0.06–0.18 μg L−1 and 0.25–500 μg L−1, respectively. Precision of the method as RSDs was evaluated which was in the range of 4.2–7.0% (within-day, n = 5) and 8.2–11.3% (between-day, n = 3). Ultimately, the method was applied to analyze two seawater samples and satisfactory results (RSDs%, 5.0–9.0%; relative recoveries, 89–104%) were obtained.

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

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

Simultaneous preconcentration and determination of zirconium in environmental samples using ultrasound-assisted ionic liquid based dispersive liquid-liquid microextraction combined with spectrophotometry

ABSTRACT The Green, delicate and rapid ultrasound-assisted ionic liquid-based dispersive liquid-liquid microextraction technique was developed to preconcentrate trace quantities of zirconium Zr(IV) ion in real samples prior to spectrophotometric detection. The proposed method uses (1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate) ionic liquid (IL) as an extraction solvent for Zr(IV) ions after the complexation with quinalizarin at pH 5.0. The effect of various analytical parameters has been investigated. The calibration graph was linear in the range of 2.0–400 µg L − 1 and the limit of detection was 0.6 µg L-1. The preconcentration factor was 100. Relative standard deviation (RSD%) at 200 µg L-1 of Zr(IV)for intra-day and inter-day precisionwere 2.0 and 2.7%, respectively (n = 10). Certified reference materialswere used to verify the accuracy.The proposed method was applied to preconcentrate and determine the content of Zr(IV) in real environmental (water, soil and plants) samples with satisfactory results.

Application of molybdenum disulfide nanosheets adsorbent for simultaneous preconcentration and determination of Cd(II), Pb(II), Zn(II) and Ni(II) in water samples

Application of molybdenum disulfide nanosheets adsorbent for simultaneous preconcentration and determination of Cd(II), Pb(II), Zn(II) and Ni(II) in water samples

Ultrasound-assisted dual-cloud point extraction with high-performance liquid chromatography-hydride generation atomic fluorescence spectrometry for mercury speciation analysis in environmental water and soil samples.

A method for simultaneous preconcentration and determination of mercury species in water and soil samples was established using high-performance liquid chromatography with hydride generation atomic fluorescence spectrometry after ultrasound-assisted dual-cloud point extraction. The extraction process was divided into two steps. In the first cloud point extraction, inorganic mercury and methylmercury formed chelates with sodium diethyldithiocarbamate and were extracted into Triton X-114 micelles. In the second stage, a displacement reaction between sodium diethyldithiocarbamate-inorganic mercury/methylmercury and l-cysteine occurred, and the analytes entered the l-cysteine aqueous solution under ultrasonication. This aqueous solution was directly introduced to the high-performance liquid chromatography with hydride generation atomic fluorescence spectrometry and the detection was completed within 6min. Under the optimum experimental conditions, the linear range was 0.10-5.0 μg/L (r ≥0.9993) for inorganic mercury and methylmercury, and the enhancement factors were 15.7 for inorganic mercury and 6.35 for methylmercury. The limits of detection for inorganic mercury and methylmercury were 0.004 and 0.016 μg/L, respectively. The approach was successfully applied to the determination of trace inorganic mercury and methylmercury in water and soil samples with good recoveries (85.3-110%). This method solved the problem of peak fusion of the two analytes and was successfully applied to the speciation analysis of mercury.