Simultaneous Determination of Nickel(II) and Cobalt(II) by Second-Derivative Spectrophotometry

4-(2-Pyridylazo) resorcinol, PAR, is shown to be useful for simultaneous determination of cobalt(II) and nickel(II) using second-derivative spectrophotometric method with controlled experimental parameters. This method allows the determination of 0.20-1.25 ppm of nickel(II) and 0.25-1.50 ppm of cobalt(II) in mixtures with good precision and accuracy. This method has advantages of simplicity, speed and requires no prior separations.     

Ruthenium(III) catalyzed oxidation of hexacyanoferrate(II) by periodate in aqueous alkaline medium

Ruthenium(III) catalyzed oxidation of hexacyanoferrate(II) by periodate in alkaline medium is assumed to occurvia substrate-catalyst complex formation followed by the interaction of oxidant and complex in the rate-limiting stage and yield the products with regeneration of catalyst in the subsequent fast step. The reaction exhibits fractional order in hexacyanoferrate(II) and first-order unity each in oxidant and catalyst. The reaction constants involved in the mechanism are derived.     

The excited states of bipyridyl and phenanthroline complexes of Fe(III), Ru(II) and Ru(III): A molecular orbital study

The semiempirical zero-differential-overlap molecular orbital model which was shown in earlier papers in this series to give a good account of the charge transfer and -* spectra of Fe(II) complexes with conjugated ligands such as 2,2-bipyridyl and 1,10-phenanthroline is extended to complexes having openshell ground states, such as those of Fe(III), and to complexes of Ru(II) and Ru(III). The results are used to assign the observed charge transfer and intra-ligand absorption bands to specific orbital transitions. Observed and calculated intensities are in good agreement: reasons are advanced for the much lower intensity of the charge transfer bands in Ru(III) compared to Ru(II) complexes.     

Simple flow injection method for simultaneous spectrophotometric determination of Fe(II) and Fe(III)

The method is based on spectrophotometric determination of Fe(II) and Fe(III) at a single wavelength (530 nm) with the use of a dedicated reversed-flow injection system. In the system, EDTA solution is injected into a carrier stream (HNO₃) and then merged with a sample stream containing a mixture of sulfosalicylic acid and 1,10-phenanthroline as indicators. In an acid environment (pH ≅ 3) the indicators form complexes with both Fe(III) and Fe(II), but EDTA replaces sulfosalicylic acid, forming a more stable colourless complex with Fe(III), whereas Fe(II) remains in a complex with 1,10-phenenthroline. As a result, the area and minimum of the characteristic peak can be exploited as measures corresponding to the Fe(III) and Fe(II) concentrations, respectively. The analytes were not found to affect each other's signals, hence two analytical curves were constructed with the use of a set of standard solutions, each containing Fe(II) and Fe(III). Both analytes were determined in synthetic samples within the concentration ranges of 0.05–4.0 and 0.09–6.0 mg L⁻¹, respectively, with precision less than 1.5 and 2.6% (RSD) and with accuracy less than 4.3 and 5.6% (RE). The method was applied to determination of the analytes in water samples collected from artesian wells and the results of the determination were consistent with those obtained using the ICP-OES technique.     

Flow Injection Manifold for Simultaneous Spectrophotometric Determination of Bi (III), Pb (II)

Abstract

A FIA assembly producing a carrier with pH which can be adjusted to the desired pH value is propposed. It is based on the merging of two different solutions, one of them at constant flow-rate and the other at variable flow-rate. This manifold has been used for the simultaneous determination of Bi(III) and Pb(II) with Arsenazo III. Calibration curves are linear in the 1.0-11.0 ppm Bi (III) range at pH 0.25 and 1.0-12.1 ppm Pb (II) at pH 2.15. The effect of foreign ions is also reported.     

Separation of Ga(III) from Cu(II), Ni(II) and Zn(II) in aqueous solution using synthetic polymeric resins

Poly (acrylamide-acrylic acid-dimethylaminoethylmethacrylate), p(AM-AA-DMAEM) and Poly(acrylamide-acrylic acid)-ethylenediaminetetracetic acid disodium, p(AM-AA)-EDTANa₂ were prepared by gamma radiation-induced template polymerization technique and used for the separation of Ga (III) from Cu (II), Ni (II), and Zn (II) in aqueous media. The effect of pH and contact time on the separation process was studied. The optimum pH value for the separation process is 3–3.5. The result shows that Ga (III) is first extracted while Cu (II), Ni (II) and Zn(II) are slightly extracted at this pH value. The recovery of metals using HCl, HNO₃ and H₂SO₄ has been studied. The resins may be regenerated using 2M HCl solutions.      

Simultaneous Determination of Copper (II) and Mercury (II) by Using a Zero-Crossing Method

Abstract

The application of a zero-crossing method to the simultaneous determination of copper (II) and mercury (II) with methylethylenediaminetetraacetic acid (MEDTA) is described. The procedure does not require equations to be solved, and it is suitable for concentrations of 0.008–0.036 mg ml^?1 of copper and 0.025–0.300 mg ml^?1 of mercury. The main interferences, both anionic and cationic, were easily eliminated. The method was applied to different aqueous matrices. It was compared with an atomic absorption spectrophotometry method (AA) and good results were obtained.     

Simultaneous determination of Fe(II) and Fe(III) by kinetic spectrophotometric H-point standard addition method

The H-point standard addition method (HPSAM) for simultaneous determination of Fe(II) and Fe(III) is described. The method is based on the difference in the rate of complex formation of iron in two different oxidation states with Gallic acid (GA) at pH 5. Fe(II) and Fe(III) can be determined in the range of 0.02–4.50 μg ml⁻¹ and 0.05–5.00 μg ml⁻¹, respectively, with satisfactory accuracy and precision in the presence of other metal ions, which rapidly form complexes with GA under working conditions. The proposed method was successfully applied for simultaneous determination of Fe(II) and Fe(III) in several environmental and synthetic samples with different concentration ratios of Fe(II) and Fe(III).     

Determination of Osmium(VIII) and Palladium(II) in Mixtures by Derivative Spectrophotometry

Abstract

A sensitive method for the simultaneous determination of osmium(VIII) and Palladium(II) (up to 15 μ9/ml of Os and 11 μ9/ml of Pd) in mixtures, by first and second derivative spectrophotometry, using allyl thiourea as reagent, is described.

A statistical analysis of the results is reported.     

Sulfur-Bonded Coordination Compounds of Palladium(II) and Platinum(II) and Their Antimicrobial Activity

The synthetic, spectroscopic, and biological studies of some new palladium(II) and platinum(II) complexes derived from biologically active sulfur donor ligands 1H-indol-2,3-dione benzothiazoline (Bzt ₁ H) and 5-nitro-1H-indol-2,3-dione benzothiazoline (Bzt ₂ H) have been described. The reactions were carried out in 1:2 molar ratios. The authenticity of the benzothiazolines and their complexes has been established on the basis of elemental analyses; molecular weight determinations; and IR, ¹ H NMR, ¹³ C NMR, and UV spectral studies. Based on IR and ¹ H NMR spectral studies, a square-planar structure has been assigned to these complexes. Studies were conducted to assess the comparative growth inhibiting potential of the synthesized complexes against the benzothiazolines for a variety of fungal and bacterial strains. The studies demonstrate that the ligands and complexes possess antimicrobial properties. Further, it was noted that the growth-inhibiting potential of the complexes is greater than the parent benzothiazolines.     

Determination of Fe(II), Cu(II) and Ag(I) by using silica gel loaded with 1,10-phenanthroline

The modified silica gel with 1,10-phenanthroline adsorbed was obtained. The adsorption from aqueous solutions onto loaded silica gel of Fe(II), Cu(II) and Ag(I) and their complexes was studied. The loaded silica gel was applied to Fe(II), Cu(II) and Ag(I) reflectance spectroscopy determinations in water (detection limits 0.08, 0.03 and 0.01 ppm respectively). Visual test scales for Fe, Cu and Ag ion determinations in water were worked out.     

以氯醌酸二价阴离子为桥联配体的Fe(Ⅲ)-Fe(Ⅲ)和Mn(Ⅱ)-Mn(Ⅱ)双核配合物的合成与磁性

基于铁和锰的双核配合物在生物氧化还原过程中的重要作用及在化学的氧化还原过程中可能做为催化剂的应用前景,本文合成了两个新的以氯醌酸二价阴离子为桥联配体的Fe(Ⅲ)双核和Mn(Ⅱ)双核配合物:[Fe_2(phen)_4(μ-CA)](ClO_4)_4·2H_2O(1)和[Mn_2(phen)_4(μ-CA)](ClO_4)_2·3H_2O(2)(phen=1,10菲咯啉;CA=氯醌酸二价阴离子)。经元素分析、IR、电子光谱及磁性等测定,对两配合物进行了表征。     

New method for simultaneous determination of Fe(II) and Fe(III) in water using flow injection technique

The method exploits the possibilities of flow injection gradient titration in a system of reversed flow with spectrophotometric detection. In the developed approach a small amount of titrant (EDTA) is injected into a stream of sample containing a mixture of indicators (sulfosalicylic acid and 1,10-phenanthroline). In acid environment sulfosalicylic acid forms a complex with Fe(III), whereas 1,10-phenanthroline forms a complex with Fe(II). Measurements are performed at wavelength λ = 530 nm when radiation is absorbed by both complexes. After injection EDTA replaces sulfosalicylic acid and forms with Fe(III) more stable colourless complex. As a result, a characteristic “cut off” peak is registered with a width corresponding to the Fe(III) concentration and with a height corresponding to the Fe(II) concentration. Calibration was performed by titration of four two-component standard solutions of the Fe(II)/Fe(III) concentrations established in accordance with 2² factorial plan. The method was tested with the use of synthetic samples and then it was applied to the analysis of water samples taken from artesian wells. Under optimized experimental conditions Fe(II) and Fe(III) were determined with precision less than 0.8 and 2.5% (RSD) and accuracy less than 3.2 and 5.1% (relative error) within the concentration ranges of 0.1-3.0 and 0.9-3.5 mg L⁻¹ of both analytes, respectively.     

The Spectrophotometry Determination of Mn(III) in the Presence of Mn(IV)

Abstract

The spectra of complex of Mn(III) and Mn(IV) with pyrophosphoric acid are investigated. The molar absorption coefficient of the complex of Mn(III) with pyrophosphoric acid is 80.6/Mcm at 510nm which is close to that of Mn(IV), 110/Mcm, however, the molar absorption coefficient of the complex of Mn(HI) with pyrophosphoric acid is only 4.98/Mcm at 398nm which is much less than that of Mn(IV), 390/Mcm. Based on this absorbance difference between Mn(III) and Mn(IV) at wavelength 398nm and 510nm, a procedure of determination of Mn(III) in the presence of Mn(IV) has been developed.     

Determination of Trace Amounts of Palladium(II) by Solid-Phase Spectrophotometry

A simple and sensitive method for solid-phase spectrophotometric determination of palladium(II) at µgL^–1 level based on the reaction product of Pd²⁺ with disodium 1-nitroso-2-hydroxynaphthalene-3,6-disulphonate (Nitroso R salt) previously immobilized on Dowex 1×1 anion exchanger has been developed. The experimental factors (wavelength, pH, amount of resin, concentration of Pd²⁺ solution, volume of solution sample, equilibration time) were optimized. The advantages of this procedure as opposed to solution methods are discussed. The results obtained with synthetic solutions clearly indicate the suitability of the proposed method for real samples analysis.     

Simultaneous kinetic spectrophotometric determination of Cu(II), Co(II) and Ni(II) using partial least squares (PLS) regression

A partial least squares (PLS-1) calibration model based on kinetic—spectrophotometric measurement, for the simultaneous determination of Cu(II), Ni(II) and Co(II) ions is described. The method was based on the difference in the rate of the reaction between Co(II), Ni(II) and Cu(II) ions with 1-(2-pyridylazo)2-naphthol in a pH 5.8 buffer solution and in micellar media at 25°C. The absorption kinetic profiles of the solutions were monitored by measuring the absorbance at 570 nm at 2 s intervals during the time range of 0–10 min after initiation of the reaction. The experimental calibration matrix for the partial least squares (PLS-1) model was designed with 30 samples. The cross-validation method was used for selecting the number of factors. The results showed that simultaneous determination could be performed in the range 0.1-2 μg mL⁻¹ for each cation. The proposed method was successfully applied to the simultaneous determination of Cu(II), Ni(II) and Co(II) ions in water and in synthetic alloy samples.      

Simultaneous Determination of Perphenazine and Amitriptyline by Derivative Spectrophotometry

Abstract

Two methods have been developed for the simultaneous determination of Amitryptiline and Perphenazine: the zero-crossing (I) and the derivative ratio spectrum (II) methods and both use the derivative spectrophotometry.

The methods have been applicable in the ranges of 1 to 30 μg·ml^?1 of Amitryptiline (I and II) and between 1 and 8 μg·ml^?1 and from 1 to 7 μg·ml^?1 of Perphenazine for the methods I and II respectively. The accuracy of the proposed methods have been studied and they have been used in the determination of Amitryptiline and Perphenazine in commercially available pharmaceuticals.     

Development and Validation of Catalytic Kinetic Spectrophotometric Method for Determination of Copper(II)

A catalytic kinetic spectrophotometric method is developed for the determination of trace amounts of Cu(II). It is based on the catalytic effect of Cu(II) on the oxidation of cysteine (RSH) by hexacyanoferrate(III) in acidic medium. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of hexacyanoferrate(III) at 420nm. The optimum operating conditions regarding concentration of reagents, pH and temperature were established. The working curve is linear in the concentration range of 0–6.35ng·mL^–1. The maximum percentage error and standard deviation for determination of Cu(II) in the range of 1.27–6.35ng·mL^–1 have been calculated to be 3.9 and 0.4 respectively. The detection limit calculated was 0.15ng·mL^–1. The interference effect of several species was also investigated, and it was found that the most common cations and anions do not interfere with the determination. The developed procedure was successfully applied to the determination of Cu(II) in various synthetic and real samples. The typical feature of this procedure is that determination can be carried out at 25°C and/or in the absence of any precision thermostatic bath in the very short analysis time of one minute. The newly developed method was found to have fairly good selectivity, sensitivity, simplicity and rapidity compared to other kinetic methods.Received October 8, 2002; accepted April 7, 2003 Published online July 16, 2003     

Ruthenium(III) catalysed oxidation of l-leucine by a new oxidant,diperiodatoargentate(III) in aqueous alkaline medium

The kinetics of Ru(III) catalysed oxidation of l-leucine by diperiodatoargentate(III) (DPA) in alkaline medium at 298 K and a constant ionic strength of 0.60 mol dm⁻³ was studied spectrophotometrically. The oxidation products are pentanoic acid and Ag(I). The stoichiometry is [l-leucine]:[DPA] = 1:2. The reaction is of first order in Ru(III) and [DPA] and has less than unit order in both [l-leu] and [alkali]. The oxidation reaction in alkaline medium has been shown to proceed via a Ru(III)–l-leucine complex, which further reacts with one molecule of monoperiodatoargentate(III) (MPA) in a rate determining step followed by other fast steps to give the products. The main products were identified by spot test and spectral studies. The reaction constants involved in the different steps of the mechanism are calculated. The catalytic constant (K_c) was also calculated for the Ru(III) catalysed reaction at different temperatures. From the plots of log K_c versus 1/T, values of activation parameters with respect to the catalyst have been evaluated. The activation parameters with respect to the slow step of the mechanism are computed and discussed, and thermodynamic quantities are also determined. The active species of catalyst and oxidant have been identified.     

Simple,Selective, and Sensitive Spectrophotometric Method for Determination of Trace Amounts of Nickel（Ⅱ）, Copper （Ⅱ）, Cobalt （Ⅱ）, and Iron （Ⅲ） with a Novel Reagent 2-Pyridine Carboxaldehyde Isonicotinyl Hydrazone

A selective and sensitive reagent of 2-pyridine carboxaldehyde isonicotinyl hydrazone（2-PYAINH） was synthesized and studied for the spectrophotometric determination of nickel, copper, cobalt, and iron in detail. At a pH value of 7.0, 9,0, 9.0, and 8.0, respectively, which greatly increased the selectivity; nickel, copper, cobalt, and iron reacted with 2-PYAINH to form a 1：2 yellow-orange, 1：2 yellow-green, 1：2 yellow and 1：1 yellow complexes, with absorption peaks at 363, 352, 346, and 359 nm, respectively. Under the optimal conditions, Beer＇s law was obeyed over the ranges of 0.01-1.4, 0.01-1.5, 0.01-2.7, and 0.01-5.4 mg/L respectively. The apparent molar absorptivity and Sandell＇s sensitivities were 8.4×10^4, 5.2×10^4, 7.1×10^4, and 3.9×10^4 L·mol^-l·cm^-1, respectively, and 0.00069, 0.0012, 0.00078, and 0.0014 μg·cm2, respectively. The detection limits were found to be 0.001, 0.002, 0.003, and 0.01 mg/L, respectively. The detailed study of various interfering ions to make the method more sensitive was carried out and selective and several real samples were analyzed with satisfactory results.