o-Diketonedioxime compounds as analytical reagents for the spectrophotometric determination of nickel

Sixteen dioxime compounds, including six new compounds, were synthesized and their reactions with nickel, cobalt, iron(II, III) and copper ions were examined. The nickel chelates of the glyoxime derivatives show hardly any absorption in the visible region, and are therefore unsuitable as color reagents. The nickel chelates of the benzildioxime derivatives can be extracted into organic solvents and provide a selective color reaction, so that useful extraction-spectrophotometric methods are possible. The metal complexes of quinonedioximes are extracted into some organic solvents, and the complexes have relatively large molar absorptivities in the visible region, but the reagents are not selective. However, the molar absorptivity of the ternary complex, Ni²⁺-reagent-zephiramine, with 1,2-naphthoquinonedioxime-4-sulfonic acid was 2.03·10⁴ at 480 nm, and that of the nickel complex of 9,10-phenanthrenequinonedioxime was 2.49·10⁴at 456 nm. The compositions of the nickel-dioxime complexes were examined spectrophotometrically.     

Naphthoquinonedioxime derivatives as analytical reagents for the spectrophotometric determination of nickel

Seven naphthoquinonedioxime compounds, including five new compounds. were synthesized and their reactions with nickel, cobalt and iron(II) ions were examined. The metal chelates of these dioximes absorb in the visible region, and the molar absorptivities of the complexes are about 1 · 10⁴ 1 mole^-1 cm^-1 in

aqueous solution. The chelates can be extracted into chloroloform with zephiramine. and the molar absorptivities of the nickel chelates are about 2 · 10⁴ 1 mole^-1 cm^-1. Of the dioximes examined. 1,2-naphthoquinonedioxime-6-sulfonic acid shows the highest sensitivity for nickel; the molar absorptivity of the nickel complex extracted into chloroform with zephiramine is 2.19 · 10⁴ I mole^-1 cm^-1 at 468 nm.     

Some azo-dye reagents for the spectrophotometric determination of cadmium

2-[2-(5-Bromopyridyl)azol-4,5-dimethylphenol (BrPDMP) and 2-[2-benzothiazolylazo)-5-dimethylaminophenol (BTADAP) have been synthesised and compared, as reagents for cadmium, with the related dyes BrPADAP and BTDMP. The new dyes both form stable highly coloured 2:1 complexes with cadmium, with molar absorptivities (in o-xylene solution) of 3.8 x 10(4) 1.mole(-1).cm(-1) at 590 nm (BrPDMP) and 4.5 x 10(4) 1.mole(-1).cm(-1) at 600 nm (BTADAP). Cadmium can be determined by extraction under alkaline conditions with a solution of BTADAP in xylene. Beer's law is obeyed up to at least 16 mug of cadmium. A limit of detection of 0.15 mug has been estimated and a coefficient of variation of 3.3% at the 5 mug level was found. The only species which interfere seriously are Co(2+), Ni(2+), and Ca(2+). A 200-fold excess of zinc may be tolerated. The method has been applied to the determination of cadmium in water samples, plant materials and hair. Interferences were overcome by preliminary extraction into Aliquat/carbon tetrachloride. The acid dissociation constant of BTADAP (pK = 9.5) and formation constant of the cadmium-BTADAP complex (log beta = 15.1) have been determined.     

Some N-alkyl-naphthylazo pyridinium salts as new reagents for the spectrophotometric determination of anionic surfactants

Summary Eleven pyridinium azo dyes with straight-chain alkyl groups C_nH_2n+1–(n=6–18) and bromoalkyl groups BrC_mH_2m–(m=6–12) were synthesized with the intention of developing reagents for the determination of low levels of anionic surfactants in an aqueous medium. The effect of the alkyl chain length of these reagents on the reactivity with anionic surfactants such as sodium dodecylsulphate (SDS), sodium linear-dodecylbenzenesulphonate (DBS), sodium dodecylsulphonate (DS) and sodium laurate (SL) was studied. It was found that the alkyl chain length played an important role in the formation of ion associates and the composition of the ion associates formed. These reagents were classified into four groups with respect to the reactivity with anionic surfactants. The first group (n,m=6) reacts only with DBS. The second group (n,m=8) reacts with SDS, DBS and DS. The third group (n,m=10, 12) reacts with SDS, DBS and DS; however, the colour intensity of the DBS-ion associate was unstable. The fourth group (n=14, 16, 18) reacts with all anionic surfactants examined, and the composition of the ion associates with SDS and DS was 2:1 ([reagent]/[surfactant]) though that of the ion associates of the three reagent groups mentioned above was 1:1. The optimal conditions for the determination of anionic surfactants in river water with 1-octyl-4-(4-aminonaphthylazo)-pyridinium bromide was examined. The calibration graph was linear up to 3×10^–6 mol/l, and the apparent molar absorptivity of the ion associate was 3.8×10⁴ l mol^–1 cm^–1 (at 427 nm). The relative standard deviation for 2.4×10^–6 mol/l SDS was 4.9%. Recoveries of 88–107% were found for 8.0×10^–7 mol/l SDS in river water samples.     

Synthesis of bidentate pyridylazo and thiazolylazo reagents and the spectrophotometric determination of copper in a flow-injection system

Some pyridylazo and thiazolylazo compounds were synthesized as spectrophotometric reagents for copper(II). The water-soluble bidentate ligand, 4-(3,5-dibromo-2-pyridylazo)-N-ethyl-N-(3-sulfopropyl)aniline (3,5-diBr-PAESA), provides the greates sensitivity, forming a 1:2 Cu:L in the presence of sodium dodecylsulfate. The molar absorptivity of the complex is 1.24 × 10⁵ l modl^?1 cm^?1 at 638 nm. Copper(II) (10–200 μg l^?1) is easily and quickly (60 h^?1) determined in a flow-injection system. Application to the determination of copper(II) in serum is described.     

Some new aromatic hydroxylamines as spectrophotometric reagents for vanadium

A comparative study is described of the use of N-benzoyi-o-tolyl-, N-benzoyl-m-tolyl, N-benzoyl-p-tolyl-, N-benzoyl-p-chlorophenyl- and N-phenylacetylphenyl-hydroxylamines, as spectrophotometric reagents for the determination of vanadium, after extraction with chloroform. All the reagents form 1:2 (metal:reagent) complexes in hydrochloric acid media or at pH 4.8–6.0; the dissociation constants of the complexes are of the order of 10^-9 and 10^-8, respectively, except those of N-benzoyl-p-chloro-phenylhydroxylamine which are of the order of 10^-8 in both media. The reactions in hydrochloric acid media are more selective and sensitive than those at pH 4.8–6.0. In presence of alcohol, the wavelengths of maximum absorption decrease. The pK_a values of the hydroxylamines were determined in water and in alcohol-water (1:1) solutions.     

A spectrophotometric method for the determination of nickel

A photometric method for the determination of nickel using versene is described. Up to 20 mg of nickel can be determined with a maximum deviation of ± 0.10 mg. The effect of interfering elements, concentrations, accuracy and limitations of the method are discussed.     

Some new heterocyclic compounds as analytical reagents

A survey of the metal-complexing reactions, as determined by reactions on chromatography paper, of 44 compounds with a substituted or modified 4-(2-pyridylazo)-resorcinol (PAR) or 1-(2-pyridylazo)-2-naphthol (PAN) structure is reported.     

New reagents for the facile and sensitive spectrophotometric determination of carbofuran in its formulations and environmental samples

Facile and sensitive spectrophotometric methods were developed for the determination of carbofuran in its formulations and environmental samples by using new reagents. The methods were based on the coupling reaction of hydrolysed product of cabofuran with diazotized reagents, namely, 2,6-dibromo-4-methylaniline, 2,6-dibromo-4-nitroaniline, and 2,4,6-tribromoaniline in basic medium to give color derivatives having the absorption maximum at 468, 474, and 410 nm, respectively. The color derivatives were correspondingly stable for 40, 30, and 16 h. Beer’s law was obeyed in the carbofuran concentration range 0.2–10.0 μg/mL. The proposed methods have been found to be applicable to the determination of carbofuran in its formulations, tap and distilled water, grains, polluted water, plant material (cabbage), and soil samples. The text was submitted by the authors in English.     

Application of pyridylazo and thiazolylazo reagents in flow injection preconcentration systems for determination of metals

Pyridylazo and thiazolylazo reagents are synthetic dyes widely used in analytical chemistry. These reagents are also very attractive for use in preconcentration systems. This paper covers the application of pyridylazo and thiazolylazo reagents in flow injection systems for the determination of metals. The article discusses flow injection preconcentration systems with solid-phase extraction, precipitation and cloud point extraction. The use of pyridylazo and thiazolylazo reagents in flow injection detection systems is also presented. The relative advantages and drawbacks of these systems are discussed. The application of pyridylazo and thiazolylazo reagents in new systems is presented in the concluding part of this review article.     

Diphenylcarbazone as a sensitive reagent for the spectrophotometric determination of iridium(IV)

Summary The blue iridium(IV)-diphenylcarbazone complex, formed by heating the solutions in boiling water bath for 45 minutes, having an absorption maximum at 550 nm with maximum molar absorptivity of 1.90·10⁴l·cm^–1·mole^–1 (within 1.5 %) is recommended for the spectrophotometric determination of 40–240g iridium(IV) in 25–60 % ethanol medium. The complex formed in solutions at pH 3.5–7.0, after formation, is stable within the pH range 2.5 to 9.2. The effect of foreign ions has been investigated.

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Zusammenfassung Der blaue Iridium(IV)-diphenylcarbazon-Komplex entsteht beim Erwärmen der beiden Lösungen im siedenden Wasserbad für 45 Min. Er hat ein Absorptionsmaximum bei 550 nm und eine molare Extinktion von 1,90 × 10⁴ l·cm^–1·mole^–1. Diese Farbreaktion wird zur spektrophotometrischen Bestimmung von 40–240g Ir(IV) in 25-bis 60%igem Äthanol empfohlen. Der bei pH 3,5–7,0 entstandene Komplex ist zwischen pH 2,5 und 9,2 beständig. Der Einfluß von Fremdionen wurde untersucht.

     

A sensitive method for the ultraviolet spectrophotometric determination of chloride

A new method for the determination of chloride ion is based on the formation of phenylmercury(II) chloride, its extraction into chloroform and reaction with sodium diethyldithiocarbamate to form phenylmercury(II) diethyldithiocarbamate. This complex has spectral maxima at 257 and 297 nm. either of which can he used for quantitative purposes. The molar absorptivities are 21.3·10³ and 6.5·10³ respectively. referred to the chloride ion. The method is especially suitable for the determination of trace amounts of chloride in aqueous solution and has been applied to samples of drinking water. Amounts of chloride in the range 0.04 0.32 p.p.m. can be determined in 250-ml aqueous samples with an average relative mean error of 12%. The method can be used also for bromide and iodide, and for organomercury(11) compounds. Interferences are minimal and the method compares favourably with the standard mercury(II) thiocyanate procedure.     

Azo compounds as reagents for the voltammetric determination of molybdenum(VI)

Linear sweep voltammograms of Lumogallion IREA (pH 2), Magneson IREA (pH 2), 4-(2-pyridylazo)resorcinol (pH 4.8), and 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (pH 4.8) in the presence of molybdenum(VI) exhibit peaks at potentials more negative than the potentials of reduction peaks of the reagents by approximately 0.1 V. In all of the above cases, the heights of these peaks linearly increased with an increase in the concentration of molybdenum(VI) in the range from 5 x 10^-7 to 2.5 x 10^-6 M; thus, these peaks can be used for the determination of molybdenum. The simultaneous proportional decrease in the heights of the cathodic peaks of the reagents can be used for indirect determination of molybdenum(VI). The limits of detection without preliminary accumulation at a dropping mercury electrode with a drop time of 5 s are (1.5-3.9) x 10^-7 M, depending on the nature of the reagent and the technique used for determining the concentration.     

铟的灵敏光度测定法

我国对微量铟的显色反应研究得较少.最常用的是碱性染料萃取光度法,但操作冗繁而且苯的毒性较大.因此寻找灵敏度高而又能在水相测定铟的新方法是很有必要的. 用苯荧光酮(2,3,7-三羟基-9-苯基-6-荧光酮,PF)作显色剂的胶束增溶分光光度法已应用于锗、钼、锡、镓等的测定,但用类似的方法测铟则尚未见报道.我们的实验证明,在pH为7.7～8.9的醋酸-氢氧化铵缓冲介质中,铟与PF及氯化十六烷基吡啶(OPC)生成玫瑰红色的三元配合物,其配合比为In(III):PF:CPC=1:2:2,表观稳定常数为8.6×10~(10),摩尔吸收系数达1.28×10~5.提出用乙酸乙酯萃取分离杂质.利用本显色反应测定微量铟,方法灵敏且稳定,准确度和精密度均较好.     

Some new acridinium trifluoromethanesulfonates as spectrophotometric derivatization reagents for aromatic and aliphatic primary amines

Some new 9-substituted 10-methylacridinium trifluoromethanesuifonate (triflate) salts have been synthesized and shown to react in methanol with the model aromatic and aliphatic amines, aniline and n-butylamine, to form derivatives which absorb strongly at 445 and 439 nm, respectively. The color development is affected by heat and heating time and by the quantity of acridinium triflate used. A 10-50-fold molar excess of the triflate should be used and the solution heated at 60 degrees for 30 min. The linearity and reproducibility of the assay are improved by the presence of pyridine (for aniline) and triethylamine (for n-butylamine) in the reaction mixture. Beer's law is obeyed over the range 0-1860 ng/ml for aniline and 0-1440 ng/ml for n-butylamine, with each of the new reagents. The relative error and the precision of determination depends on the acridinium triflate used.     

Derivative spectrophotometric determination of nickel using Br-PADAP

A major problem with spectrophotometric methods for nickel is cobalt interference, because many of the reagents for nickel also react with cobalt. In this work, the interference of cobalt in the determination of nickel using 2-(5-bromo-2-pyridylaxo)-5-diethylaminophenol (Br-PADAP) was eliminated by the use of derivative spectrophotometry, using the zero-crossing method for evaluation of the derivative signal. Br-PADAP reacts with nickel(II) in the presence of Triton X-100 to form a red complex with absorption maxima at 530 and 562 nm. The reactions parameters and the conditions for the measurements of the first-derivative signal were studied and the results demonstrated that using the derivative technique, Br-PADAP can be used for nickel determination with a selectivity higher than that of ordinary spectrophotometry and with a limit of detection of 0.2 ng ml(-1). The pH should be in the range 5.0-6.0 using an acetate buffer. The determination of nickel in the presence of cobalt was performed with conventional and derivative procedures, and the results demonstrated that only the derivative method should be used and, of the methods used for evaluation of the derivative signal, the zero-crossing method is the best. The proposed procedure was used for nickel determination in steels standards. The results demonstrated that the procedure has satisfactory accuracy and precision. Cobalt interference can be also eliminated by using dual-wave-length spectroscopy.     

Highly sensitive catalytic spectrophotometric determination of ruthenium

A new and highly sensitive catalytic kinetic method (CKM) for the determination of ruthenium(III) has been established based on its catalytic effect on the oxidation of l-phenylalanine (l-Pheala) by KMnO(4) in highly alkaline medium. The reaction has been followed spectrophotometrically by measuring the decrease in the absorbance at 526nm. The proposed CKM is based on the fixed time procedure under optimum reaction conditions. It relies on the linear relationship where the change in the absorbance (DeltaA(t)) versus added Ru(III) amounts in the range of 0.101-2.526ngml(-1) is plotted. Under the optimum conditions, the sensitivity of the proposed method, i.e. the limit of detection corresponding to 5min is 0.08ngml(-1), and decreases with increased time of analysis. The method is featured with good accuracy and reproducibility for ruthenium(III) determination. The ruthenium(III) has also been determined in presence of several interfering and non-interfering cations, anions and polyaminocarboxylates. No foreign ions interfered in the determination ruthenium(III) up to 20-fold higher concentration of foreign ions. In addition to standard solutions analysis, this method was successfully applied for the quantitative determination of ruthenium(III) in drinking water samples. The method is highly sensitive, selective and very stable. A review of recently published catalytic spectrophotometric methods for the determination of ruthenium(III) has also been presented for comparison.     

A sensitive spectrophotometric method for the determination of desloratadine in tablets

A simple, rapid, and sensitive visible spectrophotometric method was developed, for the first time, for analysis of desloratadine (DE) in tablets. The method is based on the deep-blue colored TCNQ*- radical anion formed by interaction of the drug (n-donor) with 7,7,8,8-tetracyanoquinodimethane (TCNQ, pi-acceptor) in acetonitrile at ambient temperature. Optimum conditions for the reaction were investigated, absorbances were read at 843 nm, and the linearity range for concentrations of DE was found to be 1.5-13 microg/mL. The reaction product remains stable up to 8 h when kept at room temperature in the dark. The developed method was validated and successfully applied to the determination of DE in tablets. The tablets were also analyzed with a column liquid chromatography method reported in literature. The results from both methods were statistically compared by t- and F-tests. No significant difference was found for the means and standard deviations at 95% confidence level. Accuracy was examined through recovery studies. Being very simple and reliable, the method can be recommended for routine quality control analysis of DE in tablets.