Muberra Andac

A simple and selective flow-injection spectrophotometric determination of copper(II) by using acetylsalicylhydroxamic acid

A new simple, and rapid flow-injection spectrophotometric method is developed for the determination of trace amounts of Cu(II) by using a new chromogenic reagent acetylsalicylhydroxamic acid (AcSHA). The method is based on the formation of colored Cu(II)-(AcSHA)(2) complex. The optimum conditions for the chromogenic reaction of Cu(II) with AcSHA is studied and the colored (green) complex is selectively monitored at lambda(max) 700 nm. With the reagent carrier solvent (dimethylsulfoxide (DMSO) and acetate buffer, pH 4.2) flow-rate of 1 ml min(-1), a detection limit (2S) of 1 mug l(-1) Cu(II) was obtained at a sampling rate of 80 sample h(-1). The calibration graph was linear in the Cu(II) concentration range 5-120 mug l(-1). The relative standard deviation (n=10) was 0.64% for a sample containing 60 mug l(-1) Cu(II). The detailed study of various interferences confirmed the high selectivity of the developed method. The method was successfully applied to determine trace amounts of copper(II) in river and seawater samples. The accuracy of the method was demonstrated by the analysis of standard reference materials C12X3500 and C14XHS 50.

Spectrophotometric determination of copper(II) at low μg l−1 levels using cation-exchange microcolumn in flow-injection

A simple spectrophotometric flow-injection method is reported for the highly sensitive and fast determination of copper(II). The method is based on the formation of coloured Cu(II)-(4-methylpiperidinedithiocarbamate)(2) complex when the copper solutions are introduced into a tertiary reagent stream containing 4-methylpiperidinedithiocarbamate. The coloured complex is then selectively monitored at 435 nm. To increase interactions between copper(II) and colour forming reagent and preconcentrate of copper(II), a microcolumn containing strong cation exchange resins was placed between injection manifold and spectrophotometer. The system required no mixing chamber and allowed a sample throughput >60 sample h(-1). The calibration graph was linear in the range 5-100 mug l(-1). The detection limit was <0.5 mug l(-1) for 20 mul injection volume of copper(II) ion solution. The developed method was applied to environmental, copper processing water, and ore samples.

Flow injection spectrophotometric determination of iron(III) using diphenylamine-4-sulfonic acid sodium salt

A highly sensitive and very simple spectrophotometric flow-injection analysis (FIA) method for the determination of iron(III) at low concentration levels is presented. The method is based on the measurement of absorbance intensity of the red complex at 410 nm formed by iron(III) and diphenylamine-4-sulfonic acid sodium salt (DPA-4-SA). It is a simple, highly sensitive, fast, and low cost alternative method using the color developing reagent DPA-4-SA in acetate buffer at pH 5.50 and the flow-rate of 1 mL min−1 with the sample throughput of 60 h−1. The method provided a linear determination range between 5 μg L−1 and 200 μg L−1 with the detection limit (3S) of 1 μg L−1 of iron(III) using the injection volume of 20 μL. FIA variables influencing the system performance were optimized. The amount of iron(III) and total iron in river and seawater samples was successfully determined. Repeatability of the measurements was satisfactory at the relative standard deviation of 3.5 % for 5 determinations of 10 μg L−1 iron(III). The accuracy of the method was evaluated using the standard addition method and checked by the analysis of the certified material Std Zn/Al/Cu 43 XZ3F.

Spectrophotometric flow-injection analysis of mercury(II) in pharmaceuticals with p-nitrobenzoxosulfamate

A new, simple and rapid spectrophotometric FI method for the accurate and precise determination of Hg(II) in pharmaceutical preparations has been developed. The method is based on the measuring the decrease of absorbance intensity of p-nitrobenzoxosulfamate (NBS) due to the complexation with Hg(II). The absorption peak of the NBS, which is decreased linearly by addition of Hg(II), occurs at 430 nm in 2x10(-4) moll(-1) HNO(3) as a carrier solution. Optimization of chemical and FI variables has been made. A micro column consisting of several packing materials applied instead of reaction coil was also investigated. A background level of Fe(III) maintained in reagent carrier solution with NBS was found useful for sensitivity and selectivity. Under the optimized conditions, the sampling rate was over 100 h(-1), the calibration curve obtained were linear over the range 1-10 mugml(-1), the detection limit was lower than 0.2 mugml(-1) for a 20 mul injection volume, and the precision [S(r)=1% at 2 mugml(-1) Hg(II) (n=10)] was found quite satisfactory. Application of the method to the analysis of Hg(II) in pharmaceutical preparations resulted a good agreement between the expected and found values.

A simple flow injection spectrophotometric determination method for iron(III) based on O-acetylsalicylhydroxamic acid complexation

A simple and rapid flow-injection spectrophotometric method for the determination of iron(III) and total iron is proposed. The method is based on the reaction between iron(III) and O-acetylsalicylhydroxamic acid (AcSHA) in a 2 % methanol solution resulting in an intense violet complex with strong absorption at 475 nm. Optimum conditions for the determination of iron(III) and the interfering ions were tested. The relative standard deviation for the determination of 5 μg L−1 iron(III) was 0.85 % (n = 10), and the limit of detection (blank signal plus three times the standard deviation of the blank) was 0.5 μg L−1, both based on the injection volumes of 20 μL. The method was successfully applied in the determination of iron(III) and total iron in water and ore samples. The method was verified by analysing a certified reference material Zn/Al/Cu 43XZ3F and also by the AAS method.

Spectrofluorometric determination of mercury (II) with murexide

A very sensitive and selective spectrofluorometric method has been developed for Hg(II) determination in pharmaceutical and environmental samples. The method is based on measuring the decrease in fluorescence intensity of murexide after binding Hg(II) . The intensity of the fluorescence emission peak was measured at ex/em 335/435 nm in several buffer solutions (acetic acid/acetate, NaH2PO4/Na2HPO4, NH4+/NH3) targeting the pH interval 3.0–9.0. The fluorescence intensity decrease was found to be linear in the concentration range of 8 × 10−7 to 1 × 10−5 M of Hg(II) by using 5 × 10−5 M murexide in 0.1 M acetic acid/acetate buffer at pH 4.2. The detection limit was 2 × 10−7 M. This method was found to be almost free of interference from large excesses of 40 cations and anions. The method was successfully applied to the analysis of Hg(II) in synthetic mixtures, pharmaceutical preparations, and wastewater samples. The recovery was quantitative and the standard deviation for 10 replicates of a sample containing 1 × 10−6 M Hg(II) was lower than ±4%.

Spectral and thermal characterization of salophen type Schiff base and its implementation as solid contact electrode for quantitative monitoring of copper(II) ion

Salophen templated Schiff base 2,3-bis(salicylaldimino)pyridine (H2IF) has been synthesized and fully characterized by a series of different spectroscopic methods and thermogravimetric analysis (TGA). It has been also further probed electrochemically and explored as a cation recognition ionophore in the form of a polymeric membrane as selective sensor for quantitative monitoring of Cu(2+). Dielectric properties of the membrane have been studied by electrochemical impedance spectroscopy (EIS). The potentiometric results have demonstrated that the sensor exhibits very good selectivity and sensitivity towards Cu(2+) over a wide variety of cations. The electrode has a linear response to Cu(2+) with a detection limit of 4.46×10(-8) and displays a Nernstian slope (29.14 mV/decade) between pH 3.0 and 6.0 with a fast response time less than 10s. The solid contact electrodes have been exploited over five mounts period with good reproducibility. The analytical availability of the proposed electrode has been evaluated by applying in the determination of Cu(2+) ions in water samples. The structural features and complexation of ionophore with Cu(2+) have been monitored by UV-Vis spectroscopy and spectral findings have been further supported by DFT and TD-DFT calculations.

Flow injection spectrofluorimetric determination of iron(III) in water using salicylic acid

A simple and fast flow injection fluorescence quenching method for the determination of iron in water has been developed. Fluorimetric determination is based on the measurement of the quenching effect of iron on salicylic acid fluorescence. An emission peak of salicylic acid in aqueous solution occurs at 409 nm with excitation at 299 nm. The carrier solution used was 2 × 10−6 mol L−1 salicylic acid in 0.1 mol L−1 NH4+/NH3 buffer solution at pH 8.5. Linear calibration was obtained for 5–100 μg L−1 iron(III) and the relative standard deviation was 1.25 % (n = 5) for a 20 μL injection volume iron(III). The limit of detection was 0.3 μg L−1 and the sampling rate was 60 h−1. The effect of interferences from various metals and anions commonly present in water was also studied. The method was successfully applied to the determination of low levels of iron in real samples (river, sea, and spring waters).

An efficient ab initio DFT and PCM assessment of the potentiometric selectivity of a salophen type Schiff base

As a neutral carrier component for the preparation of a potentiometric membrane sensor, the affinity and selectivity of the salophen type Schiff base ligand obtained by 1:2 condensation of 2.3-diaminopyridine with salicylaldehyde toward a series of common cations has been fully examined by DFT/B3LYP and integral equation formalism polarizable continum model (IEF-PCM or only given with PCM as default input in the computations) in combination with the experimental data. Both the potentiometric measurements and DFT calculations have exhibited that the ionophore shows appreciable selectivity for Cu2+ ion over other cations. Four different approaches where the last three are the modified version of each other have been evaluated and compared with potentiometric data. Based upon the results of comparison among the approaches suggested to verify the selective behavior of ionophore toward Cu2+, PCM implemented approach having a whole computational groundwork has given well-matched results with the observed data and with the method augmented with experimental hydration energies. The foremost interferences were detected by determining potentiometric selectivity coefficients for each metal ion relative to Cu2+ and compared to the results obtained by the DFT calculations.

A new Co(III) complex of Schiff base derivative for electrochemical recognition of nitrite anion

The synthesis and characterization of a new Co(III) complex of a salphen-type Schiff base ligand, (E)-2-{[(2-aminopyridin-3-yl)imino]methyl}-4,6-di-tert-butylphenol (HL), are reported. The characterization has been carried out using X-ray single crystallographic, thermogravimetric, and spectroscopic techniques. The complex has been combined with polyvinyl chloride (PVC) membrane of various compositions and tested as an electrochemical electrode towards recognition of several anions. The electrode exhibits exceptional electrochemical recognition for the nitrite