Selective extraction, separation and speciation of iron in different samples using 4-acetyl-5-methyl-1-phenyl-1H-pyrazole-3-carboxylic acid

Facile liquid colorimetric sensor using high-density deep eutectic solvent for trace detection and speciation of iron in milk

An efficient colorimetric sensor was developed using a high-density deep eutectic solvent (HD-DES) for the trace detection and speciation of iron in various milk samples. A liquid colorimetric probe was fabricated by dissolving ferrozine (FZ) in HD-DES prepared from TBABr and PBA. The prederivatization of Fe²⁺ via complexation with FZ on the HD-DES/FZ probe provided the [Fe(FZ)₃]^4- complex, which led to a color change from pale yellow to purple before it was simultaneously extracted by HD-DES. The Fe³⁺ content was calculated by subtracting the amount of Fe²⁺ from the total Fe content following the reduction of Fe³⁺ to Fe²⁺ by L-ascorbic acid in an acid buffer. Under the optimized conditions, the proposed colorimetric sensor exhibited appreciable linearity in the concentration range of 0.003-0.04 mg L^-1, a low limit of detection (0.95 µg L^-1), high enrichment factor (50), and outstanding repeatability. The liquid colorimetric probe was successfully applied for the determination and speciation of iron in milk samples, and the results were compared with those obtained using the standard atomic absorption spectrometry method. Moreover, quantitative analysis was performed on a smartphone using the Image J application to estimate the color intensity change, which eliminated the requirement of sophisticated scientific instruments.

Discriminating detection of dissolved ferrous and ferric ions using copper nanocluster-based fluorescent probe

Discrimination and detection of specific metal ions that belong to the same metallic element with different valence states in a complex matrix is challenging. In the present work, a fluorescence method using polyvinylpyrrolidone stabilized copper nanocluster (CuNCs@PVP) as a probe for discriminating detection of ferrous (Fe³⁺) and ferric (Fe²⁺) ions was developed. The CuNCs@PVP exhibited an excellent selective response to Fe³⁺ ions in contrast to Fe²⁺ ions and other metal ions when the pH value of solution was less than 4.0. Furthermore, the fluorescence of the CuNCs@PVP could be more sensitively quenched by Fe²⁺ ions by virtue of Fenton reaction. The different response of CuNCs@PVP towards Fe³⁺ and Fe²⁺ ions under different conditions offered the potential for the discriminating detection of Fe³⁺ and Fe²⁺ ions. Based on detailed optimization of detection conditions, an excellent linear relationship between the fluorescence quenching efficiency (F/F₀) of the CuNCs@PVP and the concentration of Fe³⁺ ions over the range of 0.4-20.0 μM and of Fe²⁺ ions in the range of 0.01-0.4 μM were obtained, respectively. The detection limits for the Fe³⁺ and Fe²⁺ ions were 0.14 μM and 0.008 μM, respectively. The developed probe showed good selectivity and presented an alternative strategy for discriminating detection of Fe³⁺ and Fe²⁺ ions in complex samples.

Polyethylene glycol-bonded triethylammonium l-prolinate: a new biodegradable amino-acid-based ionic liquid for the one-pot synthesis of bis(pyrazolyl)methanes as DNA binding agents

[PEG-TEA]LP, as a new biodegradable ionic liquid catalyst, was successfully synthesized, characterized, and applied to the one-pot pseudo-five-component synthesis of bis(pyrazolyl)methanes.

Determination of iron (III) in food, biological and environmental samples

The nanodrop spectrophotometric (NDS) determination of iron (III) in water samples has been established. The proposed method is simple, selective and highly sensitive. The extraction of Fe (III)-thiocyanate complex was done by novel organic reagents such as N-phenylacetamide, N-alkylacetamide, (alkyl=butyl, hexyl and octyl group) in chloroform. The Fe (III) extract was examined in the strong acidic (HCl+H₂SO₄) solution. The maximum value of molar absorptivity was found to be 1.8×10⁵Lmol^-1cm^-1 at λ_max, 477nm (⩾9 fold enrichments) for N-octylacetamide (N-OAA). The method obeys the Beers Law within the range of 0.05μgmL^-1-6.0μgmL^-1. The detection limit and RSD value of the method were found to be 5ppb and 0.5906% respectively. The correlation coefficient, slope and intercept were calculated and found to be 0.9989, 0.1112, and 0.0048, respectively. The proposed method was successfully applied to the determination of trace amount of iron (III) in food, biological and environmental samples.

Determination of some metal ions in various meat and baby food samples by atomic spectrometry

In this paper, we report a simple and rapid solid phase extraction system for the separation/preconcentration and determination of Cd(II), Co(II), Cu(II), Fe(III), Cr(III), Pb(II), and Zn(II) ions by flame atomic absorption spectrometry (FAAS). This method is based upon the retention of metal ions on a column packed with poly[N-(3-methyl-1H-indole-1-yl)]-2-methacrylamide-co-2-acrylamido-2-methyl-1-propane sulphonic acid-co divinylbenzene] (MMAD) resin as a solid-phase extraction (SPE) sorbent at pH 8. At the optimized conditions, the limits of detection (3 s/b) between 0.12 and 1.6 μg L(-1), preconcentration factor of 100, and the relative standard deviation of ⩽1.8% were achieved (n=10). The accuracy of the method was verified by analyzing certified reference materials (CRMs) and performing recovery experiments. The developed method was successfully applied to the various natural water, meat products and baby food samples. The recoveries of analyte ions were found in added real samples and CRMs from 95% to 102%.

Ionic-liquid-based hollow-fiber liquid-phase microextraction method combined with hybrid artificial neural network-genetic algorithm for speciation and optimized determination of ferro and ferric in environmental water samples

A novel and environmentally friendly ionic-liquid-based hollow-fiber liquid-phase microextraction method combined with a hybrid artificial neural network (ANN)-genetic algorithm (GA) strategy was developed for ferro and ferric ions speciation as model analytes. Different parameters such as type and volume of extraction solvent, amounts of chelating agent, volume and pH of sample, ionic strength, stirring rate, and extraction time were investigated. Much more effective parameters were firstly examined based on one-variable-at-a-time design, and obtained results were used to construct an independent model for each parameter. The models were then applied to achieve the best and minimum numbers of candidate points as inputs for the ANN process. The maximum extraction efficiencies were achieved after 9 min using 22.0 μL of 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]) as the acceptor phase and 10 mL of sample at pH = 7.0 containing 64.0 μg L(-1) of benzohydroxamic acid (BHA) as the complexing agent, after the GA process. Once optimized, analytical performance of the method was studied in terms of linearity (1.3-316 μg L(-1), R (2) = 0.999), accuracy (recovery = 90.1-92.3%), and precision (relative standard deviation (RSD) <3.1). Finally, the method was successfully applied to speciate the iron species in the environmental and wastewater samples.

Resting eggs as new biosorbent for preconcentration of trace elements in various samples prior to their determination by FAAS

In this study, the resting eggs of aquatic creatures living in freshwater (Daphnia, Cladocera, Crustacean) ecosystems were used as a novel biosorbent extractant for synchronous preconcentration of trace Cd(II), Co(II), Cu(II), Mn(II), and Ni(II) previous to measurement by flame atomic absorpiton spectrometry (FAAS). Using column procedures, optimization studies were conducted to realize the effective adsorption of the analyte ions such as the solution pH, amount of the biosorbent, volume of the sample, interfering ions, etc. A high preconcentration factor of 67 and low relative standard deflection of ≤4.1% (n=8) were obtained. The invention constrains based on the 3 s/b criterion were 2.4 for Cd(II), 41.4 for Co(II), 4.2 for Cu(II), 3.0 for Mn(II), and 9.6 μg L(-1) for Ni(II). The accuracy of the method was verified by analysis of a certified standard reference material. The used procedure was applied to the definition of the analytes in diverse environmental samples with convincing results. Consequently, the resting eggs of Daphnia can be used as a biosorbent for preconcentration and biosorption studies.

Spectrophotometric determination of iron species using a combination of artificial neural networks and dispersive liquid-liquid microextraction based on solidification of floating organic drop

A dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) and artificial neural networks method was developed for the simultaneous separation/preconcentration and speciation of iron in water samples. In this method, an appropriate mixture of ethanol (as the disperser solvent) and 1-undecanol (as the extracting solvent) containing appropriate amount of 2-thenoyltrifluoroacetone (TTA) (as the complexing agent) was injected rapidly into the water sample containing iron (II) and iron (III) species. At this step, the iron species interacted with the TTA and extracted into the 1-undecanol. After the phase separation, the absorbance of the extracted irons was measured in the wavelength region of 450-600 nm. The artificial neural networks were then applied for simultaneous determination of individual iron species. Under optimum conditions, the calibration graphs were linear in the range of 95-1070 μg L(-1) and 31-350 μg L(-1) with detection limits of 25 and 8 μg L(-1) for iron (II) and iron (III), respectively. The relative standard deviations (R.S.D., n=6) were lower than 4.2%. The enhancement factor of 162 and 125 were obtained for Fe(3+) and Fe(2+) ions, respectively. The procedure was applied to power plant drum water and several potable water samples; and accuracy was assessed through the recovery experiments and independent analysis by graphite furnace atomic absorption spectrometry.

Old and New Flavors of Flame (Furnace) Atomic Absorption Spectrometry

This paper presents some recent applications of Flame Atomic Absorption Spectrometry (FAAS) to different matrices and samples. The time window selected was from 2006 up to March, 2011, and several aspects related to food, biological fluids, environmental, and technological samples analyses were reported and discussed. In addition, the chemometrics application for FAAS methods development was also taken into account, as well as the use of metal tube atomizers in air/acetylene flame. Preconcentration methods coupled to FAAS were discussed, and several approaches related to speciation, flotation, ionic liquids, among others were discussed. This paper can be interesting for researchers and FAAS users in order to see the state of the art of this technique.

Development of a dispersive liquid-liquid microextraction method for iron speciation and determination in different water samples

A novel, simple and efficient method for the iron (Fe) speciation and determination in different water samples was developed using dispersive liquid-liquid microextraction (DLLME) technique followed by spectrophotometric analysis. The procedure is based on complexation of Fe(II) with O-phenanthroline (O-Phen), the subsequent ion-association formation with picrate anion, then extraction of the complex using DLLME technique. Some important parameters such as the type and volume of extraction and dispersive solvents as well as the extraction time were investigated and optimized in detail. Under the optimum conditions, the calibration graphs were linear over the range of 0.025-1.0 μg mL(-1) with limit of detection of 7.5 μg L(-1). Relative standard deviation for five replicate determinations of Fe at 0.2 μg mL(-1) concentration level was calculated to be 1.2%. Average recoveries for spiked samples were determined to be between 90% and 108%. The method was applied to water samples and parenteral solutions and the amounts of Fe found in these samples using the proposed method were similar with those obtained by a standard method.