Simultaneous separation and determination of trace amounts of Cd(II) and Cu(II) in environmental samples using novel diphenylcarbazide modified nanoporous silica

Determination of the Cadmium Ions from Aqueous Solution Using EDTA Functionalized Prunus Dulcis L. Peels by Solid-Phase Extraction Method

In the present study, Prunus Dulcis L. Peels was modified with ethylenedinitrilo tetraacetic acid and used as the sorbent for the preconcentration of Cd(II) ions from aqueous media. To characterize the sorbent, scanning electron microscopy-energy dispersive X-ray spectrometer and Fourier transform infrared spectrometer analysis were used. The optimum preconcentration conditions such as pH, eluent type, sample volume, sample flow rate and foreign ions effect were determined. The mean recovery and relative standard deviation values were found to be 100.7 ± 1.5 and 4.01% for Cd(II) ions. The capacity of the sorbent was obtained 277.8 mg g^-1 from the Langmuir isotherm model. The limit of detection was calculated as 0.216 µg L^-1 (P.F:40). In order to test the accuracy and applicability of the method, certified reference material and spiked water samples were analyzed. The results demonstrated good agreement with the certified values (relative error < 10%).

Synthesis of a magnetic SBA-15-NH2@Dual-Template Imprinted Polymer for solid phase extraction and determination of Pb and Cd in vegetables; Box Behnken design

In this study, a simple one-step method was applied for extraction and determination of lead and cadmium. The significant variables in extraction and pre-concentration were identified using analysis of variance and their behavior was modeled. Dual-template imprinted polymer was synthesized on modified Mesoporous silica structures coated with Fe₃O₄ magnetic nanoparticles. The optimum condition was 6.12 for pH, 40.62 mg for the polymer amount and 17.38 for the ultrasonic time. Concentration range, correlation coefficient, limit of detection and relative standard deviation for lead were reported to be 0.5-950, 0.9988, 0.35 μg L^-1 and 3.5%, respectively. For cadmium the above mentioned figure of merits were 0.3-980, 0.9969, 0.15 μg L^-1 and 2.4%, respectively. The adsorption capacities for lead and cadmium were reported to be 10.28 and 10.38, while their imprinting factors were 5.89 and 6.36, respectively.

Highly sensitive determination of cancer toxic mercury ions in biological and human sustenance samples based on green and robust synthesized stannic oxide nanoparticles decorated reduced graphene oxide sheets

This work proposes the conventional sonochemical synthesis of nanoparticles of tin (IV) oxide on reduced graphene oxide (rGOS@SnO₂) influencing the formation of a composite with enhanced properties. The combination of SnO₂ nanoparticles with rGOS weakens the accumulation in layered structures of the latter system, which leads to better exposure of SnO₂ active sites and thus increases the conductivity of rGOS@SnO₂ composite. This validates the improved electro-catalytic activity of the composite based on previous reports for its successful utilization in the electrochemical determination of toxic contaminants. The quantitative determination of mercury ions, through the use of the electrochemical sensor based on rGOS@SnO₂ manifests several advantages such as simple operator, promptness, cost effectiveness and time independency when compared to other traditional techniques. The fabricated sensor displays two wide linear responses in the range of 0.25-705.3 μM for mercury ions, with a rapid response time about 1 s, and with a high sensitivity of 10.18 μA μM^-1 cm^-2 under optimized conditions. The accumulation of traces of mercury in the bodies of fish in the marine eco system marks the significance of its detection in real samples. The satisfactory results of the proposed sensor establish the supreme efficacy of layered nanomaterials in conjunction with nanoparticles for the simple, rapid and efficient detection of pollutants in food and biological samples.

An efficient, cost effective, sensing behaviour liquid-liquid extraction and spectrophotometric determination of copper(II) incorporated with 4-(4'-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole: Analysis of food samples, leafy vegetables, fertilizers and environmental samples

The aim of the present work is to develop an efficient, simple and selective moreover cost-effective method for the extractive spectrophotometric determination of copper(II) by using the Schiff base 4-(4'-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole [CBIMMT]. This chromogenic reagent forms a yellow coloured complex with copper(II) in acetate buffer at pH4.2. The copper(II) complex with ligand is instantly extracted into chloroform and shows a maximum absorbance at 414nm which remains stable for >48h. The composition of extracted complex is found to be 1:2 [copper(II): reagent] which was ascertained using Job's method of continuous variation, mole ratio method and slope ratio method. Under optimal conditions, the copper(II) complex in chloroform adheres to Beer's law up to 17.5μgmL^-1 of copper(II). The optimum concentration range obtained from Ringbom's plot is from 5μgmL^-1 to 17.5μgmL^-1. The molar absorptivity, Sandell's sensitivity and enrichment factor of the extracted copper(II) chelate are 0.33813×10⁴Lmol^-1cm^-1, 0.01996μgcm^-2 and 2.49 respectively. In the extraction of copper(II), several affecting factors including the solution pH, ligand concentration, equilibrium time, effect of foreign ions are optimized. The interfering effects of various cations and anions were also studied and use of masking agents enhances the selectivity of the method. The chromogenic sulphur containing reagent, 4-(4'-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole has been synthesized in a single step with high purity and yield. The synthesized reagent has been successfully applied first time for determination of copper(II). The reagent forms stable chelate with copper(II) in buffer medium instantly and quantitatively extracted in chloroform within a minute. The method is successfully applied for the determination of copper(II) in various synthetic mixtures, complexes, fertilizers, environmental samples such as food samples, leafy vegetables, and water samples. The results are compared with those obtained with a reference procedure. Good agreement was attained. All the obtained results are indicative of a convenient, fast method for the extraction and quantification of micro levels of copper(II) from various environmental matrices without use of sophisticated instrumentation and procedure. The method showed a relative standard deviation of 0.42%.

Ionic liquid mediated extraction, assisted by ultrasound energy, of available/mobilizable metals from sediment samples

A new extraction method for metals from sediment samples was developed. In this procedure, the chelating agent EDTA was combined with a minimal amount of the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate (Bmim[BF₄]), assisted by ultrasound energy. The available analytes -Cd, Cr, Cu, Ni, Pb and Zn- were extracted under optimal conditions for a 12.5 ratio (extractant volume/sample mass) with 0.005molL^-1 EDTA solution, 0.1molL^-1 NaHCO₃, 5.0mmolL^-1 Bmim[BF₄] and 7.0min of sonication time, using an ultrasonic bath (output power of 160W). The best extractions were obtained with 100W (power dissipated in the liquid). These conditions were obtained applying the univariate method. It is important to highlight that the conventional method (extraction with 0.05molL^-1 EDTA solution only) consumes 6h to extract available metals from sediment samples selectively, and with the proposed procedure the extraction time is noticeable reduced to 7.0min. Extractable metal concentrations obtained were measured by flame atomic absorption spectrometry. The results showed good agreement with those obtained by the conventional method using a Student's paired t-test.

Selective trace determination of lead ions in different agricultural products using a novel core–shell magnetic ion-imprinted polymer with the aid of experimental design methodology

One of the most toxic and hazardous elements affecting human health is lead, which is known to be a carcinogenic factor, causing harmful effects on human metabolism.

Chromium Speciation in Wastewater and Sewage by Solid-Phase Extraction Using a New Diphenylcarbazone-Incorporated Resin

A new procedure for the determination of chromium species in polluted environmental samples by flame atomic absorption spectrometry was developed in this work. A new material containing 1,5-diphenylcarbazone included in a polymeric matrix was prepared and employed as a solid-phase extraction material for selective separation of Cr(III) ions under dynamic conditions. Chromium(III) ions were retained on this sorbent with high efficiency and repeatability (95 %, RSD = 1 %) from solutions with pH 9.0. The quantitative recovery of analyte was obtained with 0.1 mol L-1 EDTA. The concentration of Cr(VI) ions was calculated from the difference between the concentration of total chromium and Cr(III) ions. The prepared sorbent exhibits good chemical and mechanical stability, sorption capacity and selectivity towards Cr(III) ions in the presence of Cu(II), Ni(II), Mn(II) and Ca(II) ions. The accuracy of the separation method was proved by analysis of reference material of wastewater RES 10.2. The developed procedure was applied for chromium speciation analysis in municipal sewage samples.

A new magnetic tailor made polymer for separation and trace determination of cadmium ions by flame atomic absorption spectrophotometry

Magnetic ion imprinted polymers have been prepared and applied for the selective extraction and trace monitoring of cadmium ions in food samples.

Facile preparation of a novel Hg(ii)-ion-imprinted polymer based on magnetic hybrids for rapid and highly selective removal of Hg(ii) from aqueous solutions

This study reveals a facile strategy to prepare magnetic Hg(ii)-ion-imprinted polymers with incorporated Fe₃O₄@SiO₂ particles for rapid and efficient removal of Hg(ii) ions, due to the soft acid–soft base interaction of Hg(ii) and allylthiourea.

Trace monitoring of silver ions in food and water samples by flame atomic absorption spectrophotometry after preconcentration with solvent-assisted dispersive solid phase extraction

In this research, a new sample treatment technique termed solvent-assisted dispersive solid phase extraction (SADSPE) was developed. The new method was based on the dispersion of the sorbent into the sample to maximize the contact surface. In this approach, the dispersion of the sorbent at a very low milligram level was achieved by injecting a mixture solution of the sorbent and disperser solvent into the aqueous sample. Thereby, a cloudy solution formed. The cloudy solution resulted from the dispersion of the fine particles of the sorbent in the bulk aqueous sample. After extraction, the cloudy solution was centrifuged and the enriched analytes in the sediment phase dissolved in ethanol and determined by FAAS. Under the optimized conditions, the detection limit for silver ions was 0.8 μg L(-1). The relative standard deviations for six separate extraction experiments for determination of 5 and 200 μg L(-1) of silver ions was 3.4 and 3.1 %. The preconcentration factor was found to be 61.7. SADSPE was successfully applied for trace determination of silver ions in water and food samples.

Application of 1-(2-pyridylazo)-2-naphthol-modified nanoporous silica as a technique in simultaneous trace monitoring and removal of toxic heavy metals in food and water samples

Solid-phase extraction is one the most useful and efficient techniques for sample preparation, purification, cleanup, preconcentration, and determination of heavy metals at trace levels. In this paper, functionalized MCM-48 nanoporous silica with 1-(2-pyridylazo)-2-naphthol was applied for trace determination of copper, lead, cadmium, and nickel in water and seafood samples. The experimental conditions such as pH, sample and eluent flow rate, type, concentration and volume of the eluent, breakthrough volume, and effect of coexisting ions were optimized for efficient solid-phase extraction of trace heavy metals in different water and seafood samples. The content of solutions containing the mentioned heavy metals was determined by flame atomic absorption spectrometry (FAAS), and the limits of detection were 0.3, 0.4, 0.6, and 0.9 ng mL(-1) for cadmium, copper, nickel, and lead, respectively. Recoveries and precisions were >98.0 and <4%, respectively. The adsorption capacity of the modified nanoporous silica was 178 mg g(-1) for cadmium, 110 mg g(-1) for copper, 98 mg g(-1) for nickel, and 210 mg g(-1) for lead, respectively. The functionalized MCM-48 nanoporous silica with 1-(2-pyridylazo)-2-naphthol was characterized by thermogravimetry analysis (TGA), differential thermal analysis (DTA), transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), elemental analysis (CHN), and N2 adsorption surface area measurement.

Synthesis and characterization of diphenylcarbazide-siliceous mesocellular foam and its application as a novel mesoporous sorbent for preconcentration and trace detection of copper and cadmium ions

We are introducing diphenylcarbazide functionalized siliceous mesocellular foam as a novel mesoporous solid-phase for the extraction of heavy metal ions including copper(ii) and cadmium(ii).

Functionalized nanospheres for efficient sequestration of cadmium ions

This manuscript reports the synthesis, characterization and the subsequent application of thiosemicarbazide functionalized nanosilica spheres in Cd(ii) ion sequestration.