Simultaneous determination of trace aluminum (III), copper (II) and cadmium (II) in water samples by square-wave adsorptive cathodic stripping voltammetry in the presence of oxine

Chemically modified flubendazole carbon electrochemical sensor for aluminum determination in food stuff, Multivitamin syrup and real water samples supported by DFT calculations, IR and morphological tools

Aluminum is a key component in nearly nourishment stuffs and medications. It is also found in treated drinking water in the form of reactive species, and aluminum salts are commonly utilized as flocculants in water treatment. Meanwhile, it was not thought to be a dangerous metal for people, but research showed a possible link with Alzheimer's disease, breast cancer, autism, and aluminum. Controlling the amount of aluminum in food processing, agriculture, and drinking water is crucial, thus newly synthesized Al(III) ion selective electrode based on innocuous reagent, flubendazole drug, has been developed. The electrode displayed Nernstian slopes of 20.11 0.47 mV decade^-1 at 25 ± 1 °C, covering a wide concentration range of Al(III) from 1 × 10^-7 to 1 × 10^-1 mol L^-1. The response mechanism is studied using IR, computational calculations, morphological tools. The developed sensor has been utilized to accurately measure Al(III) ions in genuine water samples, multivitamin syrup, and food stuff.

Quantitative Determining of Ultra-Trace Aluminum Ion in Environmental Samples by Liquid Phase Microextraction Assisted Anodic Stripping Voltammetry

Direct detecting of trace amount Al(III) in aqueous solution by stripping voltammetry is often frustrated by its irreversible reduction, resided at −1.75 V (vs. Ag/AgCl reference), which is in a proximal potential of proton reduction. Here, we described an electroanalytical approach, combined with liquid phase microextraction (LPME) using ionic liquid (IL), to quantitatively assess trace amount aluminum in environmental samples. The Al(III) was caged by 8-hydroxyquinoline, forming a superb hydrophobic metal⁻chelate, which sequentially transfers and concentrates in the bottom layer of IL-phase during LPME. The preconcentrated Al(III) was further analyzed by a square-wave anodic stripping voltammetry (SW-ASV). The resulting Al-deposited electrodes were characterized by scanning electron microscopy and powder X-ray diffraction, showing the intriguing amorphous nanostructures. The method developed provides a linear calibration ranging from 0.1 to 1.2 ng L^−1 with a correlation coefficient of 0.9978. The LOD attains as low as 1 pmol L^−1, which reaches the lowest report for Al(III) detection using electroanalytical techniques. The applicable methodology was implemented for monitoring Al(III) in commercial distilled water.

Simultaneous determination of Cd(II) and Cu(II) using stripping voltammetry in groundwater, soil and Alhagi maurorum plants in industrial and urban areas in Northern Border, Saudi Arabia with luminol as a chelating agent

The cathodic stripping voltammetry of Cu(II) and Cd(II) speciation was re-optimized by using luminol (Lu) in groundwater, soil and Alhagi maurorum plants, finding differences with the pre-existing method and a different interpretation for the electroactive species. The main findings are that optimum sensitivity is obtained at 0.3-142.5 ng/mL and 0.065-60.0 ng/mL for copper and cadmium, respectively, that the complexes responsible for adsorption on the electrode are CuLu and CdLu, and that the sensitivity of the method is much improved in the absence of dissolved oxygen. The limit of detection of the method was 0.011 ± 0.001 ng/mL for Cu(II) and 0.013 ± 0.001 ng/mL for Cd(II). The interference of some common ions: Cr(III), Fe(III), Zn(II), Ni(II), Co(II) and Mo(II) was studied. It was concluded that application of this method for the determination of Cu(II) and Cd(II) in groundwater, soil and Alhagi maurorum plants led to satisfactory results.

Colorimetric sensing of copper(II) based on catalytic etching of gold nanoparticles

Based on the catalytic etching of gold nanoparticles (AuNPs), a label-free colorimetric probe was developed for the detection of Cu(2+) in aqueous solutions. AuNPs were first stabilized by hexadecyltrimethylammonium bromide in NH3-NH4Cl (0.6M/0.1M) solutions. Then thiosulfate (S2O3(2-)) ions were introduced and AuNPs were gradually dissolved by dissolved oxygen. With the further addition of Cu(2+), Cu(NH3)4(2+) oxidized AuNPs to produce Au(S2O3)2(3-) and Cu(S2O3)3(5-), while the later was oxid-ized to Cu(NH3)4(2+) again by dissolved oxygen. The dissolving rate of AuNPs was thereby remarkably promoted and Cu(2+) acted as the catalyst. The process went on due to the sufficient supply of dissolved oxygen and AuNPs were rapidly etched. Meanwhile, a visible color change from red to colorless was observed. Subsequent tests confirmed such a non-aggregation-based method as a sensitive (LOD=5.0 nM or 0.32 ppb) and selective (at least 100-fold over other metal ions except for Pb(2+) and Mn(2+)) way for the detection of Cu(2+) (linear range, 10-80 nM). Moreover, our results show that the color change induced by 40 nM Cu(2+) can be easily observed by naked eyes, which is particularly applicable to fast on-site investigations.

Modification of gold nanoparticle loaded on activated carbon with bis(4-methoxysalicylaldehyde)-1,2-phenylenediamine as new sorbent for enrichment of some metal ions

In this study, a new sorbent based on the gold nanoparticle loaded in activated carbon (Au-NP-AC) was synthesized and modified by bis(4-methoxy salicylaldehyde)-1,2-phenylenediamine (BMSAPD). This sorbent, which is abbreviated as Au-NP-AC-BMSAPD, has been applied for the enrichment and preconcentration of trace amounts of Co(2+), Cu(2+), Ni(2+), Fe(2+), Pb(2+), and Zn(2+) ions in real samples. All metal ions under study were retained on the Au-NP-AC-BMSAPD sorbent by complexation of the ions with the BMSAPD ligand, providing an efficient preconcentration fashion. The retained metal ions were then eluted from the sorbent by HNO(3) and detected by flame atomic absorption spectrometry. The analytical parameters including pH, amount of ligand, and the nature of the eluent and solid phase were evaluated to obtain the optimum condition for the preconcentration factor. Following the optimum conditions, a preconcentration factor of 200 was obtained for all the metal ions under study with detection limits of 1.4-2.6 ng mL(-1). The method has been successfully applied for the extraction and determination of the ion content in the same real samples with recoveries in the range of 95-99.6% and a relative standard deviation lower than 4.0%.

Novel spectrophotometric method for the determination of aluminum in soda drinks packed in cans and plastic bottles

In the present work, a new spectrophotometric method was developed for the determination of aluminum in soda drinks packed in different materials. Reaction among Al(III), phenylfluorone (PF) and cetylpyridinium chloride (CPC) in slightly alkaline medium was explored for this purpose. The method was optimized regarding to its chemical parameters in order to establish better conditions in terms of sensitivity and selectivity. The results obtained showed that the concentration of CPC presented remarkable influence on the sensitivity and acted as a sensitizer for the studied system. The possible interferences of some metallic cations were evaluated and the cations Cu(II), Mn(II), and Zn(II) presented noticed interference on the Al(III) signal. So, their interference was eliminated by using EDTA with minimum loss of sensitivity. The results obtained in the determination of total aluminum in soda drinks by the developed methodology were not statistically different from those obtained by electrothermal atomic absorption spectrometry. In the optimized conditions the method presented a linear range of 5-100 microg L(-1). The limits of detection and quantification were 0.81 and 2.7 microg L(-1), respectively. The methodology was successfully applied in the determination of aluminum in 10 samples of soda drinks packed in cans and plastic bottles.

Preconcentration-separation of Co2+, Ni2+, Cu2+ and Cd2+ in real samples by solid phase extraction of a calix[4] resorcinarene modified Amberlite XAD-16 resin

A new method is described for the simultaneous preconcentration of trace metal ions. The method is based on the adsorption of Co(2+), Ni(2+), Cu(2+) and Cd(2+) ions on 2,4,6,8-tetra(2-hydroxyphenyl)-1,3,5,7(1,3)tetrabenzenzcyclooctaphane-14,16,34,36,54, 56,74,76-octol (salicylaldehyde calix[4] resorcinarenes) (new resorcinarenes derivative) modified on Amberlite XAD-16. The adsorbed analyte ions were eluted with 6 mL 3M HCl in acetone solution, which then were determined by atomic absorption spectroscopy. The influences of the analytical parameters including pH, ligand amount and solid phase ingredient, eluting solution conditions and sample volume were investigated. Common coexisting ions did not interfere with the separation and determination. The preconcentration factor is 208. The sorbent exhibited excellent stability and its sorption capacity under optimum conditions has been found to be more than 60 microg of ions per gram of sorbent. The relative standard deviation under optimum conditions is lower than 4.10%. The accuracy of the method was estimated by using different real samples.