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Background: In the current research, a green, fast and cheap extraction method based on deep eutectic solvent was developed for the preconcentration of phenylalanine. Then, high performance liquid chromatography (HPLC) as a sensitive and accurate technique was used to determine amounts of preconcentrated phenylalanine. Objective: The combination of the HPLC technique and extraction procedure using deep eutectic solvent makes it possible to find a good procedure for the preconcentration of phenylalanine in different media with acceptable precision and accuracy. Methods: Decanoic acid and tetrabuthylammonium bromide were used as the components of the green solvent. Then, the synthesized green solvent was used for the preconcentration of phenylalanine. HPLC equipped with a UV-VIS detector, a C18 column, a mixture of sodium dihydrogen phosphate 2-hydrate (20 mM, pH 6.60)-ACN (70-30%) as the mobile phase, and the wavelength of 245 nm were selected as the best separation. Results: The chief characteristic of deep eutectic solvent was identified using Fourier transform infrared spectroscopy. Central composite design to evaluate the effects of preconcentration parameters showed that the pH value of 6.31, salt concentration of 0.272 M, DES volume of 226 μL, and stirrer time of 5.60 min were suggested as the best conditions of separation. Total analysis time was 5.50 min. Conclusion: Validation of designed analysis exposed good linearity (0.015-1.50 μg/mL), suitable sensitivity, excellent preconcentration (32.50) and enrichment (21.15) factors, acceptable relative standard deviation (3.07%), and low amounts of detection limit (0.015 μg/mL). Finally, the designed method was effectively used for the determination of phenylalanine in cheese and yoghurt with relative recoveries of 113.33 to 125.00% and 94.00 to 100.00%, respectively.

The ultimate goal of the present study is to design and investigate the bio-geo-filters for nitrate removal from the runoffs. This research uses alternate layers of non-woven geotextile and granular soil to reduce and remove pollution. These layers are of paramount importance in permeability and adsorption capability. Some points have been considered for selecting the materials, including the material capability for pollution removal, their accessibility, and maximal cost-effectiveness. After conducting the permeability tests, the weight mixing ratio of the materials used in permeable reactive barriers (PRB) was considered to be 25% sand, 20% zeolite, 20% iron filings, and 10% poplar wood sawdust. For pH 7, zeolite's maximal nitrate adsorption efficiency is about 69%, sawdust 29%, and iron filings 12%. The investigation of nitrate adsorption through the final prepared PRB for different nitrate concentrations under the optimal pH conditions showed maximal adsorption of about 83% for a nitrate concentration of 150 mg/L. The more the initial nitrate concentration, the more the absorption amount. Moreover, nitrate was removed with equal amounts of absorbent at optimal pH at different times to determine the equilibrium time. The maximal removal of 100% was obtained at an equilibrium time of 96 hours. In the pollution removal test with biomass grown in the filter environment, the filter decreased the nitrate content up to 99% after nine days, i.e., the final nitrate content was reduced from 100 to 1 mg/L.

This study uses alternate layers of non-woven geotextile and granular soil to remove soluble nitrate. The mixing weight ratios of PRB materials are 25% sand, 25% anthracite, 20% zeolite, 20% iron filings, and 10% poplar sawdust. Synthetic wastewater with an initial nitrate concentration of 100 mg/l is introduced to the filter over 25 minutes of the filter breakthrough curve (BTC). The BTC from the column test is assumed as a normal curve and the obtained longitudinal dispersion coefficient is equal to 1×10− 7m2/s. The filter reduces the amount of nitrate by 99% within nine days. CTRAN/W software properly estimates the contaminant transport in the filter. However, the BTC obtained by the software cannot estimate the total time for a complete breakthrough under laboratory conditions. At the same time, it can determine the nitrate breakthrough time close to the experimental model.

In this study, inorganic sodium nitrate salt (NaNo3) was used as the tracer and BX2 piezometer was selected as an injection point and 10 other piezometers were selected as sampling points. After conducting the tracer test and sampling from piezometers and transferring all samples to the laboratory, the electrical conductivity of the samples was measured. After analyzing the results, two possible routes were identified for the leakage from the body and abutment of Shahghasem dam. The results show that the main pathway of the leakage flow was diagnosed toward the right abutment and the reason may be due to dissolution and formation of limestone holes and karstification phenomenon. Finally, it can be concluded that the sodium nitrate as tracer moved in the body and abutment of Shahghasem dam and was not adsorb by clay and silt materials; therefore, it is suggested for future tracer works.

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 de...

In this study, a new microfluidic-chip coupled with micro solid phase extraction (μ-SPE) and a RGB detection system was designed. The method was used for extraction and simultaneous determination of trace amounts of dyes with different acidic-basic properties. Erythrosine (Ery) and Crystal Violet (CV) were selected as acidic and basic model analytes, respectively. The first step of this method is based on the on-chip electromembrane extraction (CEME) of analytes from aqueous solution. The utilized microfluidic system is a single compartment that composed of three polymethyl metacrylate plates (with sandwiched structures) patterned with palm shaped helix channels. The device consisted one pair of platinum electrodes that were embedded in the acceptor phase channels in each side. The middle part was cut and used as the path of the sample. The extracted analytes by CEME were passed through the micro-packed column containing strong cation and anion exchanger sorbents respectively. Two adsorbents were separated by a polypropylene frit and sealed on each side by two polypropylene frites. Following dye adsorption on the sorbents, the colors that emerged were promptly evaluated using RGB colorimetry on a smartphone. Central composite design was used to analyze and optimize the effective parameters on extraction efficiency. The relative standard deviations (RSDs%) based on five replicate measurements were less than 7.8% for RGB and 8.6% for the spectrophotometry technique under ideal conditions. Image analysis using a smartphone yielded LOD values of 15.0 and 10.5 μg L

Iron oxide nanoparticles have diverse applications in the fields of medicine, environmental area and analytical chemistry due to features such as a large special surface and simple separation with ...

In the present work, methyl red molecularly imprinted polymeric (MR-MIP) nanostructure was synthesized using the precipitation polymerizations for the separation of MR dye from aqueous media. The as-prepared MIP was characterized using colorimetry, infrared (IR) spectroscopy, and scanning electron microscopy (SEM). In addition, vortex-assisted dispersive micro-solid phase extraction (VAD-µSPE) based on MIP nanostructure was accomplished as a simple and efficient method for selective preconcentration of low amounts of MR from aqueous solutions. The effects of important parameters such as pH, adsorbent dose, eluent volume, and vortex adsorption-desorption time on the extraction efficiency were investigated. Two techniques including UV-Vis absorption spectroscopy and solution scanometry were applied for the analysis of MR content, comparatively. In spectrophotometric determination, the highest recovery was observed at pH 3.5 after 5 and 3 min of vortex time in the adsorption and desorption steps. The preconcentration factor of 75 and a wide linear concentration range (0.010 and 2.0 mg.L

In this study, solution scanometry is presented as a highly sensitive, simple and rapid method for the colorimetric determination of palladium ion in water samples and walnut leaf. The method is based on the formation of a rose-brown complex between Pd 2+ ion and an excess of iodide in acidic medium in Plexiglas cells, which are scanned by conventional flatbed-scanner, and the colour of each cell is analysed by software written in Visual Basic (VB 6) media to determine red, green and blue values. The relative standard deviation and linear range of the method were determined to be 1.0% and 0.1–72.0 μg mL −1 , respectively. The proposed method was successfully applied for the determination of Pd 2+ ion in water samples and walnut leaf.

A sensor array composed of individual cylindrical cavities in a sheet of Plexiglas®, which served as tiny reaction compartments, has been developed previously by Abbaspour, et al. [39–41] based on holes created in the matrix sheet by laser beam. The cells containing sample solutions were scanned with a usual flatbed scanner, and then the obtained color image of each cell was analyzed with software written in Visual Basic (VB 6) media in red, green and blue (RGB) values. In this work, this simple, fast and inexpensive method has been used for determining free salicylic acid in aspirin tablets and urine in ferric nitrate solution. The results showed that Fe(III) forms a colored 1 : 1 complex with salicylic acid and the system response is linear in a concentration range of 2 – 280 μg/L of salicylic acid with a detection limit of 0.84 μg/L for pH in the range of 2.2 – 2.4. The scanner was used instead of a spectrophotometer and a series of interferences was examined.

An ultrasonic assisted supramolecular solvent based dispersion solidification liquid–liquid microexraction method was used for the separation and preconcenteration of erythrosine prior to its determination by microspectrophotometry. Under the optimal conditions, the enrichment and preconcentration factors obtained 142 and 33.33 respectively. The calibration curve was linear in the range of 1.0–100 ng/mL of erythrosine with R 2 = 0.9949. Detection limit was 0.6 ng/mL and the RSD for 7 replicate determination of 40.0 ng/mL erythrosine was ±1.4%. The applicability of the methods was examined by determining erythrosine in water and beverage samples.

In this study, trace amounts of Brown HT were extracted, pre-concentrated and determined by cloud point extraction-scanometry (CPE-scanometry) as a simple, fast and inexpensive method. The procedure is based on CPE of Brown HT from an aqueous solution, diluting the extracted surfactant-rich phase with ethanol to 500 μL, transferring the appropriate volume to Plexiglas ® cells and scanning the cells. Then, the colour of each cell was analyzed by software written in visual basic (VB 6) into red, green and blue values. Effective parameters for the extraction efficiency, such as the pH of the system, the concentration of surfactant, the equilibration temperature and equilibration time, were investigated and optimized. Under optimal conditions, the calibration curve was linear in the range of 0.06–2.60 mg L −1 . The detection limit of the proposed method was 0.04 mg L −1 . In addition, the effects of some foreign species, including cations, anions and dyes, were investigated. The method was applied successfully for the determination of Brown HT in some water samples.

Magnetic dual-template molecularly imprinted polymer (Fe3O4@SiO2-MDMIP) was prepared to enrich and determine both p-Coumaric acid (p-CA) and ferulic acid (FA) based on syringe-to-syringe magnetic solid-phase microextraction (SS-MSPME). The obtained MDMIP was characterized and recognized, and then its adsorbing performance was studied. Based on the results, the Fe3O4@SiO2-MDMIP indicated selective recognition towards p-CA and FA with large adsorption capacity. The optimization of MDMIP–SS-MSPME conditions (pH, Fe3O4@SiO2-MDMIP mass, NaCl concentration, number of cycle, and elution volume) were conducted using the central composite design (CCD). Under the optimum conditions, an effectual and a convenient method was established to determine p-CA and FA in pomegranate, grapes, and orange samples based on SS-MSPME coupling with high-performance liquid chromatography-ultraviolet (HPLC-UV). Our developed method showed the limit of detection (LOD) of 0.08 ng mL−1 for p-CA and 0.07 ng mL−1 for FA. The method also indicated good linearity with R2 > 0.99 and good recoveries of 85.12–94.96% with RSDs ≤ 5.58% spiked at three various concentration levels in pomegranate, grapes, and orange samples.

In this study, a simple, fast, portable, environment-friendly and inexpensive method, CPE-scanometry, is applied for the determination of Phenylalanine (Phe) amino acid. The extraction of analytes from water samples (15 ml) was performed in the presence of Triton X-114 as a non-ionic surfactant in a water bath environment, diluting the extracted surfactant-rich phase with alkali ethanol as a suitable solvent to 0.5 mL and transferring an appropriate volume to a special cell. The individually cylindrical cavities in the sheet of Plexiglas serve as reaction chambers. These cylindrical cavities in the sheet of Plexiglas are fabricated with a laser beam. The cells containing the analyte solution were scanned with a scanner, then the color of each cell was analyzed, by software written in Visual Basic (VB 6), to obtain the red, green and blue values. The influence of operation parameters including pH, concentrations of surfactant and electrolyte on the cloud point extraction of analyte were studied and optimum conditions were established. Under optimum condition, limit of detection (LOD), relative standard deviation (RSD) and linear range for the proposed method are obtained 0.06, 3.42 and 0.2-10.0 mg L-1 respectively. Finally, the proposed method was utilized successfully for the determination of Phenylalanine in some water and waste water samples in recoveries range 94.1–107.7%.

In the present study, the novel leaf coral-like structured composite membrane is synthesized from array growth of copper aluminum layered double hydroxide (Cu-Al LDH) onto the polyvinylidene fluoride (PVDF) membrane surface through simple hydrothermal method. The as-prepared Cu-Al LDH/PVDF composite was characterized by FE-SEM, EDS element mapping, XRD, FTIR, AFM, BET and water contact angle (WCA). The dye adsorption of as-synthesized composite was studied for removal Erythrosin B (EB) from aqueous solution. The obtained Cu-Al LDH/PVDF composite membrane exhibits higher hydrophilicity than PVDF membrane. The pseudo-second-order model properly described the adsorption kinetics of the obtained Cu-Al LDH/PVDF composite for EB. Adsorption isotherms for EB by the as-prepared composite were found to be satisfactorily fitted by the Langmuir model. The maximum adsorption capacity of the obtained Cu-Al LDH/PVDF composite was 17.36 mg g−1. The coexisting salts decreased the removal efficiency of EB on Cu-Al LDH/PVDF composite.

In the present study, the novel calcined CuAl-layered double hydroxides/carbon nanotubes/polyvinylidene fluoride (CuAl-CLDH/CNT/PVDF400) composites are fabricated via a hydrothermal, casting and calcination method. The as-fabricated CuAl-CLDH/CNT/PVDF400 composite was characterized by FE-SEM, EDS element mapping, XRD, FTIR, BET and BJH. The prepared composite applied as adsorbents to remove Carminic acid (CA) as an anionic dye from colored wastewater. The adsorption efficiency of CA by CuAl-CLDH/CNT/PVDF400 adsorbent is higher than that of the other calcined and uncalcined composites. The obtained composite in aqueous solutions applied for CA removal was investigated based on central composite design (CCD) matrix in batch mode. The adsorption kinetics of CA on obtained composite followed by intra-particle diffusion model that indicated that the limiting step in adsorption could be controlled by the diffusion process. The maximum adsorption capacity by Langmuir isotherm reached 33.44 mg g−1. Thermodynamic study represented that the adsorption of CA on to the obtained composite was an endothermic process.

In the present study, the novel grass-like structured composite membrane is fabricated by coating with manganese iron layered double hydroxide (Mn-Fe LDH) onto the polyethersulfone (PES) membrane surface through a simple hydrothermal method. The as-fabricated Mn-Fe LDH/PES composite membrane was characterized by FE-SEM, EDS element mapping, XRD, FTIR, AFM, BET-BJH and water contact angle (WCA). The removal of malachite green (MG) onto Mn-Fe LDH/PES composite membrane was investigated in batch mode. The obtained composite membrane demonstrated higher hydrophilicity than PES membrane. Their adsorption kinetics of MG on membrane followed a pseudo second-order model. The adsorption behavior and the equilibrium data were represented by the Langmuir isotherm and the maximum adsorption capacity reached 13.49 mg g−1. Thermodynamic study represented that the adsorption of MG onto the Mn-Fe LDH/PES composite membrane was an endothermic process. The influence of various salts such as NaCl, Na2CO3, KNO3 and metal ions such as Cd2+, Ni2+ and Pb2+ ions on the adsorption of MG by Mn-Fe LDH/PES composite membrane are studied.

The proton transfer compound (Hdap)(chelH)·2H2O (1) and its related anionic complex (Hdap) [VO2(chel)] (2), where chelH2 = 4-hydroxypyridine-2,6-dicarboxylic acid (chelidamic acid) and dap = 3,4-diaminopyridine, were synthesized and characterized by elemental analysis, spectroscopy (IR, UV–Vis), thermal (TG/DTG) analysis and single-crystal X-ray diffraction. Compound 1 resulted from proton transfer between chelH2 and dap in aqueous solution. In 1, two carboxylic acids of chelH2 were deprotonated and the protons transferred to the nitrogen atoms of one chelidamate anion and one dap moiety. Compound 2 resulted from complexation of 1 and vanadyl sulfate. In the crystal structure of 2, the metal ion is five coordinated by one tridentate ligand (chel)2− and two O2− anions, with (Hdap)+ as a counter cation. In both structures, a complicated hydrogen-bonding network accompanied with π–π, C–O···π and C–H···π stacking interactions leads to formation of a 3D supramolecular network. In the following, solution studies have been performed by means of pH potentiometric titrations method as a power technique. This method was used for determination of protonation constants of chelH2 and dap in their probable protonated forms and for calculation of equilibrium constants for the chelH2–dap proton transfer system and the stoichiometry and stability constants of binary and ternary complexes of this system with VO2+ ion in aqueous solution. The stoichiometries of the most complex species in solution were compared with the corresponding crystalline complexes in the solid state.

The acidity constant, pKa, of bromophenol blue (BPB) and phenol red (PR) indicators was determined by solution scanometry as a new, simple, fast and inexpensive method. The method is based on scanning of the cells containing the indicator solution with a scanner and then the color of each cell is analyzed with software written in visual basic (VB 6) media to red, green and blue values. The cells were built by creating holes in the Plexiglas® sheet. In addition, the acidity constants of the cited two indicators were determined spectrophotometrically. Hypspec program has been developed for the calculation of pKa values based on spectrophotometric data. Bromophenol blue and phenol red structures are similar and two pKa were found attributed to the phenolic groups. The agreement between the acidity constants calculated by solution scanometry, spectrophotometric method and values reported in the literature demonstrates the utility of the method here used. In addition, the Hyss2009 program was used for drawing of the corresponding distribution diagrams.

Compound DAPH+Cl−·3H2O (1), and complexes Mn(dipic)(H2O)3 (2) and [DAPH][Zn(dipicH)(dipic)]·4H2O (3), (dipicH2 = 2,6-pyridinedicarboxylic acid and DAP = 2,3-diaminophenazine) were prepared from the reaction of MgCl2·4H2O and ZnCl2 with mixture of o-phenylenediamine (OPD) and 2,6-pyridinedicarboxylic acid in water. These compounds were characterized by elemental analysis, FTIR, 1H NMR and UV–Vis spectroscopy. The solid-state structure of [DAPH][Zn(dipicH)(dipic)]·4H2O (monoclinic, P21/c) was determined by the single crystal X-ray diffraction method. The protonation constants of dipic and DAP, in all of probability protonated forms, the equilibrium constants for the dipic–DAP proton transfer system and the stoichiometry and stability constants of binary and ternary complexes of this system with Zn2+ and Mn2+ ions in aqueous solution were investigated by the potentiometric pH titration method. The stoichiometries of the most complex species in solution were compared with corresponding crystalline complexes in the solid state., We gratefully acknowledge the support of this work by the Sistan and Baluchestan University. Financial support from Spanish Ministerio de Economia y Competitividad (MAT2013-40950-R) and ERDF funding is acknowledged.

The trace amounts of Violet Covasol as a cosmetic dye was determined by an efficient cloud point extraction-Scanometry (CPE-Scanometry) method. This method has many advantages such as novelty, facility, high speed, sensitivity, low cost and safety. The method is based on the CPE of an analyte from an aqueous solution, diluting the extracted surfactant-rich phase with ethanol, transferring to Plexiglas® cell and scanning of the cells containing the analyte solution with a scanner and measuring the RGB parameters with software written in visual basic (VB 6) media. Parameters impacting the extraction efficiency such as pH of the system, the concentration of surfactant, equilibration temperature and time were optimized. Detection limit (DL), relative standard deviation (RSD) and linear range for the proposed method are 0.026, 0.71 and 0.16–6.6 μg mL−1 respectively. The method was successfully applied for the determination of Violet Covasol dye in several water samples, including a water sample containing the dye as a tracer (to investigate subsurface water movement).

In this work, the magnesium content was determined by the solution scanometric method using titan yellow (TY) as a complexing agent in alkaline media. This method is based on scanning a solution containing the pink-coloured product of the combination of TY and the magnesium hydroxide complex. Hydroxylamine hydrochloride (HA) and starch were utilised as colour stabilizers and protective colloids, respectively. After the cells containing the sample solution were scanned, the colour of each cell was analysed with software written in Visual Basic (VB 6) in terms of the red, green and blue values. The parameters used for optimisation include the reaction time and the concentration of TY, sodium hydroxide, starch and HA. The system had a wide linear range between 0.070 and 30.000 μg mL −1 concentrations of magnesium, with a detection limit of 0.058 μg mL −1 and a relative standard deviation of 1.90% for the G colour value. In addition, the effects of some foreign species were investigated. The method was successfully applied for the determination of magnesium in almond gum and three water samples.

A simple, efficient, rapid and environmentally friendly method has been developed for preconcentration and determination of ultratrace amounts of uranyl ion in water sample by a supramolecular based-ligandless ultrasonic assisted-dispersion solidification liquid–liquid microextraction procedure before spectrophotometric detection. The methodology is based on the dispersion-solidification liquid–liquid microextraction of uranyl ion with decanoic acid/THF supramolecular solvent in the absence of chelating agent. Several factors affecting the microextraction efficiency, such as pH, type and volume of supramolecular solvent, sonication time, and ionic strength were investigated and optimized. Under the optimized conditions, the enhancement factor and preconcentration factor were obtained as 54.43 and 33.33 respectively. The calibration curve was linear in the range of 4.00 to 311.85 ng mL−1 of uranyl ion with R2 = 0.9967 and the detection limit based on three times the standard deviation of the blank (3Sb) was 2.00 ng mL−1 in the original solution. The relative standard deviation for seven replicate determination of 125.00 ng mL−1 uranyl ion was ±2.87%. The developed method was successfully applied to the extraction and determination of uranyl ion in natural water samples.