A new coprecipitation method without carrier element for separation and preconcentration of some metal ions at trace levels in water and food samples

Difunctional Fluorescent Probes for Iron and Hydrogen Sulfide Detection Based on Diphenyl Derivative

In order to better monitor the content of Fe3+ and H2S in the biological environment, two new fluorescent probes were designed and synthesized. With the addition of Fe3+, the strong fluorescence emission of two probes was significantly quenched due to the paramagnetic effect of Fe3+. With the further addition of S2-, the fluorescence intensity was quickly restored. Two probes showed high selectivity and strong sensitivity for the detection of Fe3+ and S2-, and the fluorescence intensity "ON-OFF-ON" was accompanied with the interaction process. At the same time, two probes displayed good anti-interference ability which was not interfered by the existence of other ions. In addition, two probes illustrated fast response time to Fe3+, S2- and small cytotoxicity to cells. Therefore, two probes can provide a potential ideal tool for detecting Fe3+ and H2S in organisms and the environment.

A new method for extraction and pre-concentration of the heavy metals using a microemulsion system in winsor II equilibrium and determination by HR-CS AAS

For the very first time, a microemulsion system in the Winsor II (WII) equilibrium was applied in a sample preparation method for extraction and pre-concentration in the determination of Pb, Cd, Co, Tl, Cu and Ni, in natural waters by high resolution continuum source atomic absorption spectrometry (HR-CS AAS). The method was optimized using the graphite furnace atomization. A simplex-centroid design for determine optimum extraction condition (77.5% aqueous phase, 5% of the oil phase, and 17.5% cosurfactant/surfactant ratio - C/S = 4) was applied. The optimized time for the sample preparations was around 30 min. The analytical performance of the optimized method using HR-CS GF AAS showed that the detection limits were: 0.09, 0.01, 0.06, and 0.05 μg L-1 for determination of Pb, Cd, Tl, and Co, respectively and the enrichment factors were between 6 and 19, considered excellent for all analytes. The RSD values were lower than 5%, demonstrating the good precision of the proposed method. When the optimized method was applied using the HR-CS F AAS, the sensibility increased 9 to 12 times for Cu and Ni, respectively. The analytical method was successfully applied for the determination of analytes in Certified Reference Material and real samples for natural waters such as Brackish water (recovery between 107 and 112%), Saline water (recovery between 83 and 94%), Produced water from oil industry (recovery between 98 and 110%) and Fresh water (recovery 80 and 87% to Cu and Ni respectively). All the results confirming the accuracy of the analytical method proposed. The repeatability of the measurements has been better 5% (n = 3), for all elements.

A new Fe3+-selective, sensitive, and dual-channel turn-on probe based on rhodamine carrying thiophenecarboxaldehyde: Smartphone application and imaging in living cells

A new dual-channel probe based on rhodamine B derivative (MSB) was successfully designed, synthesized, characterized by Nuclear Magnetic Resonance (NMR) Spectroscopy, Fourier Transform Infrared Spectrophotometer (FTIR), Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS), X-ray Photoelectron Spectroscopy (XPS), and Single Crystal X-rayDiffraction, and the sensing abilities toward Fe³⁺ cation have been demonstrated and the probe was successfully utilized for fluorescence imaging of Fe³⁺ in living cells. The probe demonstrated quite fast, sensitive, and selective response to Fe³⁺ by causing an extreme enhancement in UV-vis and fluorescence spectroscopy techniques in the buffered aqueous media which makes MSB a dual-channel probe. While the color of MSB solution was initially light yellow, it turned pink in the presence of Fe³⁺, which provided highly selective naked-eye determination among several ions as alkaline, alkaline-earth, and transition metal ions. After that, the probe was easily applied to paper strips and real samples such as drinking waters and supplementary iron tablets for sensing Fe³⁺ in an aqueous solution. The detection limit (LOD) and the response time of the probe were determined as 4.85x10^-9 M and 4 min, respectively, which are quite lower compared with other rhodamine based Fe³⁺ sensors in the literature. According to Job's plot, ¹H NMR titration, MALDI-TOF MS, XPS, and DFT study techniques, the complexation ratio between MSB and Fe³⁺ was found as 1:1. Moreover, the spectral response was reversible with alternately addition of Fe³⁺ or Na₂EDTA to the MSB solution. In addition, fluorescence imaging in NIH/3T3 mouse fibroblast cells and studies in real samples with a quite high recovery rate exhibited that the probe is qualified for detection of Fe³⁺ ion with multiple practical usages.

Green synthesis of reusable super-paramagnetic diatomite for aqueous nickel (II) removal

Adsorption is an effective method for treating wastewater containing nickel due to its minimal equipment requirements and flexible operation. Therefore, an environmental friendly, inexpensive, efficient and recyclable adsorbent is needed. In this work, a reusable dual-functional super-paramagnetic adsorbent was prepared by combining APTES (3-Aminopropyltriethoxysilane) and EDTA (ethylenediaminetetraacetic acid disodium) with magnetic diatomite for the removal of Ni²⁺. It is named diatomite/CoFe₂O₄@APTES-EDTA (DECFASEs). The synthetic material was characterized and studied by XRD (X-ray Powder Diffractometer), FTIR (Fourier Transform Infrared Spectrometer), SEM (Scanning Electron Microscope), TEM (Transmission Electron Microscope), EDS (Energy Dispersive Spectrometer), VSM (Vibrating-Sample Magnetometer), BET (Brunauer-Emmett-Teller) method, Zeta potential analyzer and XPS (X-ray Photoelectron Spectroscopy), respectively. The performance of adsorption Ni²⁺ by DECFASEs was studied on effect of pH, reaction time and initial concentrations. The adsorption and desorption capacity and recyclability of the adsorbent material were estimated. A adsorption kinetic data had a significant correlation with the pseudo second-order kinetic and also adsorption isotherm data corresponded well with Freundlich adsorption isotherm. The maximum adsorption capacity of the adsorbent material was 19.22 mg/g. The Ni²⁺ adsorption capacity of DECFASEs decreased slightly from 9.11 to 8.25 mg/g after 4 recycles. The XPS results of DECFASEs before and after Ni²⁺ uptake showed N and O participated in the complexation of Ni²⁺ in the adsorption process, which verified the chemical interaction between Ni²⁺ and DECFASEs. Modified-diatomite is a promising adsorbent for aqueous Ni²⁺ removal.

Ultrasound-Assisted Ionic Liquid Microextraction for Preconcentration of Cadmium in Water, Vegetables and Hair Samples Prior to FAAS Determination

Background::

Cadmium (Cd2+) is considered to be one of the most important hazardous heavy metals due to its toxicity for living organisms at low concentration levels. Therefore, the estimation of trace Cd2+ in different types of various samples is a very important objective for chemists using effective methods. In the present work, a novel, green, easy and fast ultrasoundassisted ionic liquid-dispersive liquid phase microextraction technique (UA-IL-DLPME) was developed to preconcentrate and determine trace quantities of cadmium (Cd2+) ions from real samples, prior to detection by FAAS.

Methods:

The proposed technique is based on utilization of ionic liquid (IL) (1-hexyl-3- methylimidazolium tris(pentafluoroethyl)trifluorophosphate [HMIM][FAP]) as an extraction solvent for Cd2+ ions after complexation with 2-(6-methylbenzothiazolylazo)-6-nitrophenol (MBTANP) at pH 7.0. The impact of different analytical parameters on the microextraction efficiency was investigated. The validation of the proposed procedure was verified by the test of two certified reference materials (TMDA-51.3 fortified water, SRM spinach leaves 1570A) applying the standard addition method.

Results:

In the range of 2.0-200 μg L−1, the calibration graph was linear. Limit of detection, preconcentration factor and the relative standard deviation (RSD %, 100 μg L-1, n=5) as precision was 0.1 μg L-1, 100 and 3.1%, respectively.

Conclusion:

Green UA-IL-DLPME method was developed and applied to preconcentrate and determine trace quantities of Cd2+ in real water, vegetables and hair samples with satisfactory results.

Green Dispersive Micro Solid-Phase Extraction using Multiwalled Carbon Nanotubes for Preconcentration and Determination of Cadmium and Lead in Food, Water, and Tobacco Samples

Background:

Cadmium (Cd2+) and lead (Pb2+) have acute and chronic effects on humans and other living organisms. In the present work, new, green and accurate dispersive micro solid-phase extraction (DμSPE) method for the separation and preconcentration of trace amounts of cadmium (Cd2+) and lead (Pb2+) ions in various food, water and tobacco samples collected from Saudi Arabia prior to its Flame Atomic Absorption Spectrometric (FAAS) determinations was developed.

Methods:

The proposed method was based on a combination of oxidized multiwalled carbon nanotubes (O-MWCNTs) with a new chelating agent 5-benzyl-4-[4-methoxybenzylideneamino)-4H- 1,2,4-triazole-3-thiol (BMBATT) to enrich and separate trace levels of Cd2+ and Pb2+. The effect of separation parameters was investigated. The validation of the proposed preconcentration procedure was performed using certified reference materials.

Results:

Analyte recovery values ranged from 95-102%, indicating that the method is highly accurate. Furthermore, precision was demonstrated by the relative standard deviation (RSD < 3.0%). The limits of detection were 0.08 and 0.1 μg L−1 for Cd2+ and Pb2+ ions, respectively. The preconcentration factor was 200.

Conclusion:

The proposed method was used for the estimation of Cd2+ and Pb2+ ion content in various real samples, and satisfactory results were obtained. The proposed method has high adsorption capacity, rapid adsorption equilibrium, extremely low LODs, high preconcentration factors and shortens the time of sample preparation in comparison to classical SPE.

Preconcentration of Lead in Blood and Urine Samples Among Bladder Cancer Patients Using Mesoporous Strontium Titanate Nanoparticles

In this work, mesoporous strontium titanate nanoparticles (SrTiO₃ NPs) were synthesized through a single-step combustion process and were characterized by FT-IR, XRD, SEM-EDX, and TEM. The effects of main parameters that may influence the extraction process (i.e., pH, sorbent amount, time of extraction, eluting agent, and the presence concomitant ions) were investigated. The optimum extraction was achieved at pH 6, 50 mg of sorbent, 20-min shaking time, and 4.0 mL of 0.1 mol L^-1 thiourea as desorption agent. Under these conditions, the maximum adsorption capacity was 155.6 mg g^-1 with a preconcentration factor of 250 (for a 1000 mL sample solution). The calibration graph was linear up to 1000 μg L^-1 and the limit of detection was 1.75 μg L^-1. The precision (as relative standard deviation) was 2.53% (n = 10). The procedure was employed for the preconcentration of Pb²⁺ from blood and urine samples of bladder cancer patients before its determination by FAAS.

Deep Eutectic Solvent Based Air Assisted Ligandless Emulsification Liquid-Liquid Microextraction for Preconcentration of Some Heavy Metals in Biological and Environmental Samples

In this study, a deep eutectic solvent (DES) based on air-assisted ligandless emulsification liquid-liquid microextraction method (DES-AA-LL-ELLME) was considered for preconcentration and extraction of some metals (Cd, Ni, Pb and Cu). A 1:1 mixture of the synthesized DES and triethylamine was added as an extractant to extract metal ions in the absence of chelating agent. Tetrahydrofuran as the aprotic solvent provided a turbid state. To disperse the aggregated DES droplets into the aqueous phase, air-assisted was performed. The influence of several effective parameters was monitored. Under optimum conditions, limits of detection were found in the range of 0.31-0.99 µg L^-1 with preconcentration factor from 67 to 69. The relative standard deviation (n = 10) was in the range of 2.1%-3.1% for all analytes. This procedure was applied to determine some metals in both biological and environmental samples with appropriate recoveries about 98.7%-106%.

Zwitterion-functionalized polymer microspheres as a sorbent for solid phase extraction of trace levels of V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II) prior to their determination by ICP-MS

This paper describes the preparation of zwitterion-functionalized polymer microspheres (ZPMs) and their application to simultaneous enrichment of V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II) from environmental water samples. The ZPMs were prepared by emulsion copolymerization of ethyl methacrylate, 2-diethylaminoethyl methacrylate and triethylene glycol dimethyl acrylate followed by modification with 1,3-propanesultone. The components were analyzed by elemental analyses as well as Fourier transform infrared spectroscopy, and the structures were characterized by scanning electron microscopy and transmission electron microscopy. The ZPMs were packed into a mini-column for on-line solid-phase extraction (SPE) of the above metal ions. Following extraction with 40 mM NH₄NO₃ and 0.5 M HNO₃ solution, the ions were quantified by ICP-MS. Under the optimized conditions, the enrichment factors (from a 40 mL sample) are up to 60 for the ions V(V), As(III), Sb(III) and Hg(II), and 55 for Cr(III) and Sn(IV). The detection limits are 1.2, 3.4, 1.0, 3.7, 2.1 and 1.6 ng L^-1 for V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II), respectively, and the relative standard deviations (RSDs) are below 5.2%. The feasibility and accuracy of the method were validated by successfully analyzing six certified reference materials as well as lake, well and river waters. Graphical abstract Zwitterion-functionalized polymer microspheres (ZPMs) were prepared and packed into a mini-column for on-line solid-phase extraction (SPE) via pump 1. Then V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II) ions in environmental waters were eluted and submitted to ICP-MS via pump 2.

Development of cloud-point extraction method for preconcentration of trace quantities of cobalt and nickel in water and food samples

A new, efficient, and sensitive cloud point methodology was developed for preconcentration of trace quantities of cobalt and nickel in water and food samples.

Triethylenetetramine modified multiwalled carbon nanotubes for the efficient preconcentration of Pb(ii), Cu(ii), Ni(ii) and Cd(ii) before FAAS detection

Triethylenetetramine modified multiwalled carbon nanotubes (TETA-MWCNTs) were prepared and used as an efficient adsorbent for the solid phase extraction of heavy metal ions.