Spectrophotometric Determination of Gadolinium(III) With O-Hydroxyhydroqoinonephthalein in Mixed Micelles of N-Hexadecylpyridinilm Chloride and Brij 35

Abstract

A sensitive, simple and selective spectrophotometric method for the determination of gadolinium(III) is proposed using o-hydroxyhydroquinonephthalein(Qnph), by analogy with phenylfl-uorone(Phfl), in the presence of N-hexadecylpyridinium chlo-ride(HPC)-Brij 35 mixed surfactants. The calibration curve is rectilinear in the range of 0 – 16.0 μg per 10 ml at 590 nm with an apparent absorption coefficient(?) of 1.2 × 10⁵ 1 cm^?1 mol^?1 and Sandell sensitivity of 0.0013 μg/cm² gado-linium(III).     

Color Reaction Between 4-(2-Pyridylazo)Resorcinol and Mercury (II) in the Presence of Surfactant,and Improved Spectrophotometric Determinations of Mercury(II) and Cyanide Ion with its Coloring

Abstract

The reactions among 4-(2-pyridylazo)resorcinol (PAR), mercury(II) and/or cyanide ion in the presence of water soluble surfactants alone or combination were systematically investigated at about pH 9. The spectrophotometric determinations of mercury(II) and cyanide ion were investigated by using the PAR-mercury(II)-HPC complex (3:2:2 molar ratio) in the presence of N-hexadecylpyridinium chloride (HPC) alone; calibration graphs were rectilinear in the ranges of 0 – 40 μg mercury(II) and 0 –10 μg cyanide ion in a final 10 ml with the apparent molar absorptivities of 5.9 × 10⁴ for mercury(II) and 2.5 × 10⁴ 1 mol^?1 cm^?1 for cyanide ion at 590 nm. The proposed method had advantages—rapidity, simplicity without solvent extraction, and sensitivity in comparison with reported solvent extraction methods. The interference of foreign ions decreased 1/2–l//4-fold compared with that in the presence of non-ionic surfactant alone.     

Xylenol Orange,Zirconium(IV) and Fluoride Color Reaction in Mixed Micelles of N-Hexadecylpyridinium Chloride and Brij 35, and Its Analytical Application1

Abstract

The color reaction between Xylenol orange (XO), zirconium (IV) and fluoride ions in the presence of various surfactants alone or in combination was studied at various pH. The XO -zirconium)IV)-fluoride ion ternary complex in mixed micellar media containing a low concentration of N-hexadecylpyridinium chloride (HPC) as a cationic surfactant and large amounts of (poly{oxyethylene)dodecyl ether (Brij 35) as a nonionic surfactant at weakly acidic media was found to be the most stable, and showed a remarkable bathochromic shift and clear contrast against a reagent blank. The maximum absorbance was at 600 nm in the mixed micellar media at pH 3.5, and the apparent molar absorptivities at 600 nm were 7.0 × 10⁴ 1 mol^?1 cm^?1 for zirconium(IV) and 1.4 × 10⁴ 1 mol^?1 cm^?1 for fluoride ion. The calibration curves covered the ranges of 0.5 ～ 20.0 μg/10 ml zirconium! IV) and 0 ～ 20.0 μg/10 ml fluoride ion with the Sandell sensitivities being 0.0013 μg/cm² for zirconium(IV) and 0.0016 μg/cm² for fluoride ion.     

Spectrophotometric Determination of Piroxicam via Chelation with Fe(III) in Commercial Dosage Forms

The objective of this work is to develop and validate spectrophotometric method for the determination of piroxicam in commercial dosage forms. The method is based on the chelation of the drug with Fe(III) to form pink coloured metal chelate at room temperature which absorbs maximally at 504 nm. Beer's law is obeyed over the concentration range of 8–160 μg mL^?1 (A = 1.07 × 10^?3 + 7.75 × 10^?3 C). Under the optimized experimental conditions, proposed method is validated as per the International Conference on Harmonisation guidelines. The limits of detection and quantitation for the proposed method are 0.775 and 2.348 μg mL^?1, respectively. The proposed method has been successfully applied to the determination of piroxicam in commercial dosage forms. The results are compared with the reference El‐Ries et al. spectrophotometric method.     

Spectrophotometric Determination of Nickel(II) with O-hydroxyhydroquinonephthalein in the Mixed Micellar Media of Zephiramine and Tween 20

Abstract

The effect of mixed surfactants on the color reaction between nickel(II) and o-hydroxyhydroquinonephthalein(Qnph) was examined in weakly basic media. The color development of the metal complex in the presence of cationic and nonionic surfactants (mixed micellar media of Zephiramine (Zp) and Tween 20) was very stable and exhibited a high and reproducible absorbance. The calibration curve was linear in the ranges of 0 – 7.0 μg nickel(I1) in a final volume of 10 ml at 545 or 536 nm. The method developed does not require an organic solvent extraction step. The apparent molar absorptivity and Sandell sensitivity were 1.26 × 10⁵ 1 per mol per crn and 0.0045 μg per cmL nickel(II), respectively, at 545 nm.     

The Affinity of Gallium(III) and Indium(III) for Nitrogen Donor Ligands

Abstract

Dedicated to Professor Arthur Martell on the occasion of his seventy fifth birthday.

The complexes of In(III) and Ga(III) with a variety of nitrogen donor ligands were studied in aqueous solution by glass electrode potentiometry at 25°C in 0.1 M NaNO₃. The ligands were 2-aminomethylpyri-dine (AMPY), ethylenediamine (EN), N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine (THPED), and N,N-bis(2-hydroxyethyl)glycine (BICIN). A variety of mixed ligand complexes of the MLOH type were detected with many of the above ligands as L. The logK₁ values obtained were with Ga(III) 8.40 (AMPY), 7.94 (THPED) 12.72 (EN), and In(III) 7.6 (AMPY), 8.20 (THPED), and 7.06 (BICIN). These formation constants are discussed in relation to previous predictions that In(III) and Ga(III) would have a substantial chemistry with nitrogen donor ligands. Of particular interest is the Ga(III) system with EN, where a very stable Ga(EN)³⁺ complex is formed, but no higher complexes except for hydrolyzed species such as Ga(EN)OH²⁺ and Ga(EN)(OH)₂ ⁺.     

Fluorometric Determination of Iron(Iii) with O-Hydroxyhydroquinonephthalein in the Presence of Brij 58

Abstract

A highly sensitive fluorescence reaction of iron(III) with o-hydroxyhydroquinonephthalein (Qnph) in the presence of various surfactants, and its application to the fluorophotometry of trace amounts of iron(III) is described. the method is based on the fluorescence quenching reaction between Qnph and iron(III) in the presence of Brij 58 at pH 3–4. the quenching calibration graph was linear over the range 0 – 300 ng per ml iron(III) by using fluorescence reaction at Em 525 nm with Ex 470 nm, and the iron(III) detection limit was 5 ng/ml. the proposed method is simple, rapid and does not involve heating or solvent extraction.     

Solubility of gallium(III) oxyhydroxide in aqueous NaCl solutions at 100°C

The hydrolysis-precipitation equilibrium reaction of aqueous gallium(III) solution was investigated in 0–3 mol-kg^-1 NaCl media at low pH at 100°C using a pressure-tight glass vessel. All precipitates were identified as GaOOH. The results were analyzed with a nonlinear least-squares computer program to obtain the solubility product K_so for gallium(III) oxyhydroxide using a single-parameter type of Debye-Hückel equation. The value of log K_so for GaOOH(s) + 3H⁺ ⇆ Ga³⁺ + 2H₂O was -0.60 at 100°C. The solubility product calculated from thermodynamic data was compared with the experimental result.     

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.     

Spectrophotometric Determination of Trace Chromium(VI) in Mass Chromium(III)

There is little conclusive evidence of the toxic effects of Cr(III) so far, but Cr(VI) has carcinogenic activity, so the analysis of the chromine ions is very important in environmental research and the quality control of industry products. Usually Cr(III) and Cr(VI) interfere with each other in the species analysis, the measurement of Cr(VI) of numerous previous papers is related to the Cr(VI) samples, which contain a little Cr(III). When the amount of trivalent chromine exceeds ten …     

Determination of dissociation constants for coordination compounds of Cr(III) and Co(III) using potentiometric and spectrophotometric methods

The acid–base properties of analogous complex ions of chromium(III) and cobalt(III) in aqueous solution have been studied. The equilibrium constants for all metal complexes were determined by using potentiometric and spectrophotometric titration methods. First, dissociation constants for the studied complexes of Cr(III) and Co(III) were determined by means of the potentiometric titration method and using the STOICHIO computer programme. Then, pH-spectrophotometric titrations were performed and the OriginPro 7.5 computer programme was used to calculate the same constants. The measurements using both methods were carried out under the same conditions of temperature, T = 298.15 K, and over the same pH range 2.00–10.00, respectively. It turned out that the two methods used enabled us to obtain acidity constants in very good agreement.     

Flow Injection Spectrophotometric Determination of Dipyrone in Pharmaceutical Formulations Using Fe(III) as Reagent

A flow injection spectrophotometric procedure with symmetric merging zones for dipyrone determination in pharmaceutical formulations is proposed. The determination is based on the formation of a blue complex (monitored at a wavelength of 642 nm) yield in the complexation reaction of dipyrone with Fe(III) in acid medium. Under optimum conditions, a calibration curve was obtained from 3.5 to 281 mg L^?1 with a detection limit of 2.8 mg L^?1 and the samples throughput was 80 h^?1. The analytical results obtained for commercial formulation samples by applying the proposed method were in good agreement with labeled values and those obtained by a comparative procedure at a 95% confidence level.     

用胶束液相色谱模拟生物膜预测药物的醇-水分配系数log P

通过比较药物在不同类型表面活性剂的胶束液相色谱中的容量因子与药物的醇-水分配系数(log P)的相关性, 发现药物在非离子型表面活性剂Brij35作为流动相的胶束液相色谱中的容量因子与其文献中报道的log P间有一定的相关性, 进一步考察了Brij35浓度对药物保留的影响, 并建立了药物在不同浓度的Brij35胶束液相色谱中的容量因子与文献中log P的相关关系, 该方法简单、快速, 将为药物的疏水性评价提供重要的参考价值.     

Metallomicellar Catalysis: Hydrolysis of Phosphodiester with Cu(II) and Zn(II) Complexes in Micellar Solution

Abstract

The effects of two metal complexes of 2,2′‐dipyridylamine (bpya) ligand, [(bpya)Cu]Cl₂ and [(bpya)Zn]Cl₂, in promoting the hydrolysis of bis(4‐nitrophenyl) phosphate (BNPP) have been kinetically investigated in Brij35 micellar solution and at 298 K, pH ranging from 6.41 to 8.6. In neutral micellar solution at 298 K, pH 7.02, the rate constants for the catalytic hydrolysis of BNPP by [(bpya)Cu]Cl₂ and [(bpya)Zn]Cl₂ are 1.2 × 10⁶ times and 1.5 × 10⁵ times higher than those for the spontaneous hydrolysis, respectively. Kinetic studies show that the active species in the catalytic hydrolysis of BNPP is the aquo‐hydroxy form, and the relative kinetic and thermodynamic parameters indicate that the mechanism of the reaction involves intramolecular nucleophilic attack on the metal center‐bound diester.     

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.     

Cu(II) promoted oxidation of L-valine by hexacyanoferrate(III) in cationic micellar medium

The kinetics of Cu(II) accelerated L-valine (Val) oxidation by hexacyanoferrate(III) in CTAB micellar medium were investigated by measuring the decline in absorbance at 420 nm. By adjusting one variable at a time, the progression of the reaction has been inspected as a function of [OH⁻], ionic strength, [CTAB], [Cu(II)], [Val], [Fe(CN)₆³⁻], and temperature using the pseudo-first-order condition. The results show that [CTAB] is the critical parameter with a discernible influence on reaction rate. [Fe(CN)₆]^3- interacts with Val in a 2:1 ratio, and this reaction exhibits first-order dependency with regard to [Fe(CN)₆³⁻]. In the investigated concentration ranges of Cu(II), [OH⁻], and [Val], the reaction demonstrates fractional-first-order kinetics. The linear increase in reaction rate with added electrolyte is indicative of a positive salt effect. CTAB significantly catalyzes the process, and once at a maximum, the rate remains almost constant as [CTAB] increases. Reduced repulsion between surfactant molecules' positive charge heads brought on by the negatively charged [Fe(CN)₆]^3-, OH⁻, and [Cu(OH)₄]^2- molecules may be responsible for the observed drop in CMC of CTAB.     

Spectrophotometric Studies of Cerium(III) and Thorium(IV) Chelates of Diethylenetriaminepentaacetic Acid (DTPA)

The interaction between diethylenetriaminepentaacetic acid (DTPA or H_sZ) and Ce(III) and Th(IV) ions has been investigated spectrophotometrically in aqueous solution at an ionic strength of 0.1 and for various temperatures. It has been found that the Ce(III)-DTPA chelate (1:1) exhibited a characteristic absorption maximum at 297 nm, and the optimum pH range is between 3.4 to 4.4. The absorption of Ce(III)-DTPA chelate is considerably diminished by adding small amounts of Th(IV) ions. This phenomenon was used to evaluate the formation constant of Th(IV)-DTPA chelate (1:1). The formation constants and the thermodynamic properties characterizing the formation of the chelates have been calculated at 25°. The results are as follows:      

Mononuclear gallium(III) complexes based on salicylaldoximes: Synthesis,structure and spectroscopic characterization

The reactions of Ga(acac)₃ with salicylaldoxime (saoH₂) and methyl-salicylaldoxime (Me-saoH₂) in dichloromethane/hexane afforded the complexes [Ga(acac)(saoH)₂] (1) and [Ga(acac)₃][Ga(acac)(MesaoH)₂] (2), respectively, in high yields. The crystal structures of 1 and 2 have been determined by single-crystal X-ray crystallography. Both complexes are mononuclear with the Ga(III) atoms being in octahedral environments surrounded by two bidentate chelate R-saoH⁻ and one bidentate chelate acac⁻ ligands. A [Ga(acac)₃] moiety has co-crystallized along with the methylsalicylaldoximato complex. Characteristic IR as well as NMR data are discussed in terms of the nature of bonding in the structures of the two complexes. ¹H and ¹³C NMR data in CDCl₃ indicate that the salicylaldoximato complexes isomerize in solution.     

Spectrophotometric Determination of Copper(II) as the Azide Complexes,in the Presence of Iron(III) Cations

Abstract

A method for the spectrophotometrio determination of copper(II), in the presence of iron(III) cations (excess), was stablished. The masking of iron is made with sodium fluoride salt in 50 % (v/v) water/acetone medium. In the recommended conditions, absorbances for cupric complexes are measured at 435 nm where molar absorptivity is 6.00 × 10³ 1 mol^?1 cm^?1.

The stable ayetern obeys Beer's law and is suitable for the copper determination in concentration range from 2.0 to 9.0 mg 1^?l. The iron(III) ion interference (until ca. 600 mg 1^?l) can be completely suppressed. The influence of diverse ions and several others factore were studied.

The results show that copper(II) can be accurately determined by azide apectrophotometric method, if the samples were suitablely treated by the recommended procedure.     

Flow Injection Spectrofluorimetric Determination of Terbium (III) Based on Solubilizing its Ternary Complex in Micellar Solution

Abstract

A flow injection spectrofluorimetric method has been developed for the determination of terbium (III) based on solubilizing its ternary complex with pi valoyitrifluoroacetone (PTA) and trioctylphosphine oxide(TOPO) in micellar solution of nona (oxyethylene) dodecyl ether (BL-9EX). Accuracy and reproducibility are good up to 16 ng/ml of terbium (III) and 80 samples per hour can be analyzed. The relative standard deviation was less than 1.0 %. No interferences from 20-fold excesses of 11 rare earth ions were observed.