Indirect complexometric determination of cadmium(II) using 1,10-phenanthroline as selective masking agent

An indirect complexometric method is described for the determination of cadmium(II), 1,10-phenanthroline being used as masking agent. Cadmium(II) in a given sample solution is initially complexed with an excess of EDTA and the surplus EDTA is titrated with lead nitrate solution at pH 5.0–6.0 (hexamine), using xylenol orange as indicator. An excess of 1,10-phenanthroline is then added and the EDTA released from the Cd-EDTA complex is titrated with standard lead nitrate solution. Results are obtained for 1.5–57 mg of Cd with relative errors 0.90% and standard deviations 0.06 mg. Cu(II), Co(II), Hg(II), Ni(II), Zn(II), Pd(II), Tl(III), Au(III) and Sn(IV) interfere, but can be easily masked. The method is applied for the determination of cadmium in synthetic alloy solutions.     

Fourth-derivative spectrophotometric determination of neodymium in mixed rare earths with methyl thymol blue and cetylpyridinium chloride

A sensitive and selective method is described for the determination of neodymium in mixed rare earths using fourth-derivative spectrophotometry. The method is based on the absorption spectra of 4f electron transitions of the complex of neodymium with methyl thymol blue and cetylpyridinium chloride. The influence of various instrumental parameters and reaction conditions for maximum colour development are investigated. The calibration curve is linear over the range 0–3.5 g ml^–1 neodymium. The relative standard deviation for determination of 1.4 g ml^–1 neodymium (n = 7) is 1.6%. The detection limit (signal-to-noise ratio = 3) is 0.2 g ml^–1.     

克拉霉素与百里酚蓝荷移配合物的光度分析研究

利用克拉霉素与百里酚蓝在乙醇介质发生荷移反应,建立了荷移分光光度法测定克拉霉素含量的方法.结果表明,荷移反应生成1∶1型配合物,最大吸收波长为442 nm,表观摩尔吸光系数为ε=1.66×104L·mol-1·cm-1,克拉霉素测定线性范围为8.278～57.59 mg/L.     

Spectrophotometric and derivative spectrophotometric determination of nickel with hydroxynaphthol blue

The reaction of nickel(II) cation with hydroxynaphthol blue (HNB) in aqueous media at pH 5.2–6.0 results in a red complex that is stable for at least 2h. Beer's Law is obeyed up to 3.2 g/ml of nickel(II) with an apparent molar absorptivity of 1.38 × 10⁴l/mol/cm at 563 nm. This paper proposes procedures for nickel determination by ordinary and first-derivative spectrophotometry. The results demonstrate that the linear dynamic range is 0.08–3.20 g/ml with a limit of detection of 23 ng/ml for ordinary spectrophotometry, compared with 21–800 ng/ml and 6 ng/ml, respectively, for first-derivative spectrophotometry. Calcium(II), magnesium(II), barium(II), strontium(II), cadmium(II), lead(II), manganese(II), bismuth(III) and molybdenum(VI) ions do not interfere for at least 1001 mass ratios. The main interferents are cobalt(II), titanium(IV), aluminium(III), mercury(II) and copper(II). The interferences of titanium(IV), aluminium(III), zirconium(IV) and iron(III) can be masked by fluoride and mercury(II) and copper(II) with thiosulfate or thiourea. The derivative method is applied to nickel determination in standard brasses and the results demonstrate that there is no significant difference between the results and certified values at the 95% confidence level.     

Sequential injection spectrophotometric determination of iron as Fe(II) in multi-vitamin preparations using 1,10-phenanthroline as complexing agent

A sequential injection analysis (SIA) system is proposed for the determination of iron (II). Fe(II) was determined by SIA based on the reaction between 1,10-phenanthroline and iron (II), yielding an orange–red colour complex with absorption maximum at 512 nm. The method involved aspiration of 187 μl sample/standard zone followed by a zone of a reagent solution containing 140 μl of 7.8 × 10⁻⁴ mol l⁻¹ 1,10-phenanthroline into a carrier stream to be stacked inside a holding coil and flow reversed through a reaction coil to a detector. The optimum condition was evaluated and the calibration curve is linear over a range of 0.25 to 5.0 mg l⁻¹ of Fe(II) with detection limit of 18 μg l⁻¹. A sample throughput of 40 h⁻¹ was established. This technique is found to be simple, accurate, reproducible and sensitive. The proposed method was successfully applied for the determination of total iron as Fe(II) in pharmaceutical products (multi-vitamin tablets) and is especially useful for the determination of iron (II) in tablets with lower iron (II) contents. The results were found to be in good agreement with the results obtained by manual UV/Vis spectrophotometry and flame atomic absorption spectrometry (FAAS) and with claimed values by the manufacturers.     

Displacement reactions of 2-chloro- and 2,9-dichloro-1,10-phenanthroline: synthesis of a sulfur-bridged bis-1,10-phenanthroline macrocycle and a 2,2′-amino-substituted-bis-1,10-phenanthroline

The synthesis and structural assignments of 9-chloro-1,1-phenanthroline-2(1H)-thione and 1,10-dihydro-1,10-phenanthroline-2,9-dithione have been accomplished. The sulfur-bridged bis-1,10-phenanthroline macrocycle was readily prepared by heating the thione or equimolar amounts of the dithione and 2,9-dichloro-1,10-phenanthroline in diphenyl ether. Displacements of 2-chloro- or 2,9-dichloro-1,10-phenanthroline with N,N-dimethylethylenediamine afforded the corresponding amine and diamino analogues. An amino-substituted-2,2′-bis-1,10-phenanthroline has been prepared.     

Preconcentration of Cd(II) and Cu(II) by solid phase extraction on cyanopropyl modified silica columns using 1,10-phenanthroline as the complexing agent

We describe the solid-phase extraction for the preconcentration and determination of Cd(II) and Cu(II) aqueous samples by inductively coupled plasma optical emission spectrometry. The preconcentration of analytes is accomplished by retention of their chelates with 1,10-phenanthroline in aqueous solution on a solid phase containing cyanopropylsilane bonded to silica gel in a column. The preconcentration factor is 80 for the cadmium ions and 120 for the copper ions with relative standard deviations of between 0.5 and 1.5%. The limits of detection (defined as “3 s” where “s” is the standard deviation of the blank determination) are 0.18 and 0.073 μg L⁻¹ for Cd(II) and Cu(II), respectively, and the corresponding limits of quantification (6 s) are 0.36 and 0.15 μg L⁻¹, respectively. As a result, a simple method was created for simultaneous preconcentration and determination of the metals in reference material and in plant sample material. Correspondence: Bożena Puzio, Institute of Chemistry, Silesian University, 40-006 Katowice, Poland     

Spectrophotometric and first-derivative spectrophotometric determination of cadmium witho-hydroxybenzenediazoaminoazobenzene (HDAA)

The synthesis ofo-hydroxybenzenediazoaminoazobenzene (HDAA) is described. Cadmium forms with HDAA in the presence of Triton X-100 a 13 complex, which gives a maximum absorption at 520nm with an apparent molar absorptivity of 1.97 × 10⁵1 · mol^–1 · cm^–1 in pH 10 borax buffer solution and 1.52 × 10⁵1 · mol^–1 · cm^–1 in ammoniacal medium. In both media, Beer's law is followed in the range of 0 –10 g of cadmium in 25ml of solution and the coefficients of variation do not exceed 1.5%. A derivative method has been employed to determine cadmium in certain waste water samples without separation.     

Unprecedented stable aqueous semiquinone methide radical formation interferes with adsorptive cathodic stripping voltammetry of cobalt methyl thymol blue

A putatively highly sensitive and selective method for the determination of cobalt in aqueous samples by catalytic adsorptive cathodic stripping voltammetry using methyl thymol blue (MTB) as the ligand has been documented [A. Safavi, E. Shams, Talanta 51 (2000) 1117] and its underlying mechanism has been briefly explored [A. Safavi, E. Shams, Electroanalysis 14 (2002) 708]. In an attempt to adapt the method for application in metalloprotein analysis we obtained erratic results, which were traced down to the redox non-innocence of the free ligand in the potential range prescribed for the metal analysis. On the hanging mercury drop electrode free methyl thymol blue is reversibly one-electron reduced to the semiquinone form with E_m,7.0 = −482 mV versus NHE at 22 °C, and the radical is subsequently quasi-reversibly one-electron reduced to the quinol form with E_m,7 ≈ −0.9 V. This observation invalidates the use of MTB in electrochemical analysis of metal ions. This is also the first observation ever of a stable quinone methide radical in aqueous solution.     

苯胺蓝增色光度法测定食盐中的碘

在H2SO4介质中,KIO3与苯胺蓝反应增色程度与IO3-量在一定范围内呈线性关系,从而建立了增色光度法测定碘的新方法.实验结果表明,该体系最大吸收波长为603 nm,IO3-在0.91～4.55 μg/L范围内符合比耳定律,表观摩尔吸光系数为5.00×105 L·mol-1·cm-1.本法可直接测定食盐中的碘.     

Saccharin complexes of zinc(II) with phenanthroline and 2,9-dimethyl-1,10-phenanthroline: synthesis and characterization

The saccharinato complexes [Zn(phen)₂(sac)(H₂O)]sac (1) and [Zn(sac)(dmp)(H₂O)](sac) (2), where phen = 1,10-phenanthroline, dmp = 2,9-dimethyl-1,10-phenanthroline, and sac =saccharinato ion/ligand, were synthesized by the reaction of [Zn(sac)₂(H₂O)₄] · 2H₂O with ligands and have been characterized by elemental analysis, IR, and ¹H NMR spectroscopies. Conductivity of complexes was measured in DMSO. Compound 1 is characterized by single crystal X-ray diffraction and compared with some isomorphous zinc-saccharinate complexes reported previously. Complex 1 crystallizes in the triclinic system, space group P 1 , with Z = 2, and consists of alternating slightly distorted octahedral [Zn(phen)₂(sac)(H₂O)]⁺ and noncoordinated saccharinate. The zinc bound aqua is hydrogen bonded to an oxygen of carbonyl in the saccharinate ligand and the SO₂ group in the saccharinate counter-ion from an adjacent molecule. Intermolecular and intramolecular hydrogen bonds and C–H ··· O and C–H ··· N short contacts lead to a 3-D network.     

Crystal Structure and Properties of a Terbium m -methylbenzoate Complex with 1,10-phenanthroline

A terbium m -methylbenzoate complex with 1,10-phenanthroline, [Tb( m -MBA) 3 phen]·H 2 O has been obtained from ethanol solution, where m -MBA= m -methylbenzoate and phen=1,10-phenanthroline, and its structure determined by X-ray diffraction methods. The unit cell contains binuclear molecules of the title compound. Each Tb 3+ ion is eight-coordinated to one 1,10-phenanthroline molecule, one bidentate carboxylate group and four bridging carboxylate groups, for which the carboxylate groups are bonded to the terbium ion in two modes chelating bidentate and bridging bidentate. Excitation and luminescence data observed at room temperature show that the complex emits very intense green fluorescence under ultraviolet light. Results of thermal analysis indicate that the complex is quite stable to heat.     

Utilization of activating and masking effects by ligands for highly selective catalytic spectrophotometric determination of copper and iron in natural waters

A kinetic–catalytic spectrophotometric method is proposed for the successive determination of nanogram levels of copper and iron, which is based on their catalytic effects on the oxidative coupling of p-anisidine with N,N-dimethylaniline (DMA) to form a colored compound (λ_max=740 nm) in the presence of hydrogen peroxide at pH 3.2. 2,9-Dimethyl-1,10-phenanthroline (neocuproine) acted as an activator for the copper catalysis, and 1,10-phenanthroline (phen) acted as an activator for the iron catalysis. The selectivity was improved in the presence of diphosphate as a masking agent. The determinable ranges were 0.16–10 ppb for copper and 1–100 ppb for iron, respectively. The relative standard deviations of copper and iron were 1.1 and 0.97% for five determinations of 10 ppb copper and 40 ppb iron. The method was successfully applied to the analyses of copper and iron in tap, well, river and pond waters.     

A new flow-injection determination of glucose based on the redox reaction of hydroquinone with iron(III) in the presence of 1,10-phenanthroline

A new spectrophotometric flow-injection (FI) method is proposed for the determination of glucose based on the redox reaction of hydroquinone with iron(III). When a glucose solution containing quinone is passed through the immobilized glucose oxidase column introduced in FI system, quinone is reduced to hydroquinone by glucose. In the presence of 1,10-phenanthroline (phen), iron(III) is then quantitatively reduced by hydroquinone to iron(II) followed by the formation of iron(II)-phen complex (λ_max=510 nm). An FI peak observed at 510 nm corresponds to the concentration of glucose. The wide dynamic range for glucose was obtained in the range of 1×10⁻⁶–1×10⁻³ mol l⁻¹ at a sampling rate of 24 h⁻¹ and the detection limit (S/N=3) was 5×10⁻⁷ mol l⁻¹. Relative standard deviations were 0.78, 0.44 and 0.23% (n=5) for 5×10⁻⁶, 5×10⁻⁵ and 5×10⁻⁴ mol l⁻¹ of glucose, respectively. The proposed method was successfully applied to the determination of glucose in control blood sera, human blood plasma and wine.     

A novel flow injection chemiluminescence determination of Cr(VI) with Dichlorotris(1,10-phenanthroline)ruthenium(II)

A selective novel reverse flow injection system with chemiluminescence detection (rFI-CL) for the determination of Cr(VI) in presence of Cr(III) with Dichlorotris (1,10-phenanthroline)ruthenium(II), (Ru(phen)₃Cl₂), is described in this work. This new method is based on the oxidation capacity of Cr(VI) in H₂SO₄ media. First, the Ruthenium(II) complex is oxidized to Ruthenium(III) complex by Cr(VI) and afterwards it is reduced to the excited state of the Ruthenium(II) complex by a sodium oxalate solution, emitting light inside the detector. The intensity of chemiluminescence (CL) is proportional to the concentration of Cr(VI) and, under optimum conditions, it can be determined over the range of 3-300 μg L⁻¹ with a detection limit of 0.9 μg L⁻¹. The RSD was 8.4% and 1.5% at 5 and 50 μg L⁻¹, respectively. For the rFI-CL method various analytical parameters were optimized: flow rate (1 mL min⁻¹), H₂SO₄ carrier concentration (20% w/V), Ru(phen)₃Cl₂ concentration (5 mM) and sodium oxalate concentration (0.1 M). The effect of Cr(III), Fe(III), Al(III), Cd(II), Zn(II), Hg(II), Pb(II), Ca(II) and Mg(II), was studied. The method is highly sensitive and selective, allowing a fast, on-line determination of Cr(VI) in the presence of Cr(III). Finally, the method was tested in four different water samples (tap, reservoir, well and mineral), with good recovery percentage.     

Synthesis and electrical properties of CuBr<Subscript>2</Subscript> complexes with 1,10-phenanthroline monohydrate

Using 1,10-phenanthroline monohydrate and CuBr₂ in molar ratios of 1:1 and 2:1, in CH₃OH/H₂O (ϕ_r = 1:1), the complexes [(phen)CuBr₂]₂, (I), and {[(phen)₂CuBr]Br·H₂O}, (II), have been prepared. The hydrogen bondings and aqua bridges between coordinated and noncoordinated bromides of II have been observed by XRD. Complex II has a triclinic crystal structure with distorted trigonal bipyramidal coordination geometry. Possibilities of ligand exchange with hydroxide or ammonia have been examined in both complexes. While the mononuclear complex II is stable in a refluxed ammonia solution and the complex {[phen)₂CuBr]Br·3H₂O}, (IV), trihydrate of II, is obtained; the binuclear complex I reacts with the ammonia solution to replace one of its bromides in the subunits with hydroxide to give {[(phen)₂Cu₂Br₂(OH)₂]·4H₂O}, (III). Structural and electrical properties of the complexes have been investigated by elemental analysis, vibrational and electronic spectroscopy, mass spectrometry, TGA, XRD and the four-point probe method. The temperature coefficients of resistivity and the activation energies of the complexes have also been obtained. All complexes behave as intrinsic semiconductor in the temperature range of 310–440 K.     

On-line solid phase extraction system using 1,10-phenanthroline immobilized on surfactant coated alumina for the flame atomic absorption spectrometric determination of copper and cadmium

An on-line solid phase extraction (SPE) preconcentration system coupled to flame atomic absorption spectrometer (FAAS) was developed for determination of copper and cadmium at μg L⁻¹ level. The method is based on the on-line retention of copper and cadmium on a microcolumn of alumina modified with sodium dodecyl sulfate (SDS) and 1,10-phenanthroline and subsequent elution with ethanol and determination by FAAS. The effect of chemical and flow variables that could affect the performance of the system was investigated. The relative standard deviation (n = 6) at 20 μg L⁻¹ level for copper and cadmium were 1.4 and 2.2% and the corresponding limits of detection (based on 3σ) were 0.04 and 0.14 μg L⁻¹, respectively. The method was successfully applied to determination of copper and cadmium in human hair and water samples.     

Synthesis and structure of Mn(II) and Zn(II) complexes containing 1,10-phenanthroline unit

The Mn(II) and Zn(II) complexes of N,N′-diisopropyl-1,10-phenanthroline-2,9-dimethanamine have been synthesised, and the structure of the two complexes have been studied by X-ray crystallography.     

钐-邻硝基苯甲酸与1，10-邻菲咯啉配合物的热分解动力学

The complex of Sm₂(o-NBA)₆(PHEN)₂ (o-NBA, o-Nitrobenzoate; PHEN, 1,10-phenanthroline) was prepar-ed and characterized by elemental analysis, IR and UV spectraoscopy. The thermal decomposition mechanism of Sm₂(o-NBA)₆(PHEN)₂ was studied under a static air atmosphere by TG-DTG. The thermal decomposition kinetics of the complex for the first stage was studied under non-isothermal condition. The most probable mechanism functions of the thermal decomposition reaction for the first stage are: G(α)=[-ln(1-α)]^1/2, f(α)=2(1-α)[-ln(1-α)]^1/2. The activation energy E for the first stage is 259.50 kJ·mol^-1, the pre-exponential factor A is 36.19×10¹⁸ min^-1. The lifetime equation at weight-loss of 10% was deduced as lnτ=-36.70+27 572.12/T by isothermal thermogravimetric analysis.     

Spectrophotometric and titrimetric determination of gallium in minerals and ores using semimethylthymol blue

The composition, overall stability constant and molar absorptivity of the chelate of gallium(III) ion with semimethylthymol blue, SMTB, were determined spectrophotometrically in acetate buffer (pH 4.5–5). A violet Ga(SMTB) chelate was formed with logarithmic overall stability constant of 18.0±0.1 (I=0.1) and molar absorptivity of 4.25×10⁴l mol^–1cm^–1 (_max 580 nm). SMTB is proposed as a new reagent for the spectrophotometric determination of micro-molar amounts of gallium(III). The colour development depends on time, temperature, pH and buffer species. The interference of different cations, anions and organic acids on gallium(III) determination was also investigated. Beer's law was obeyed for 3.5–31.3 gGa(III)/25ml (0.14–1.25 g ml^–1). SMTB was used for the spectrophotometric determination of gallium in different grade minerals and ores and the results were of acceptable error and relative standard deviation. Comparison between the two suggested methods and atomic absorption spectrometry for Ga(III) determination was carried out.