1-(1,2,4-Triazolyl-3-azo)-2-naphthol as a spectrophotometric reagent for inorganic ions

The synthesis, characteristics and analytical reactions of 1-(1,2,4-triazoly 1-3-azo)-2-naphthol are described. Coloured complexes are formed with 21 metal ions. For the cadmiuin(II) complex, the molar absorptivity is 2.8 × 10⁴ 1 mol^-1 cm^-1 at 515 nm for 40% ($\text{v}\text{v}$) ethanolic solutions at pH 8.0. For the mercury(II) complex at pH 10, the molar absorptivity is 2.7 × 10⁴ mol^-1 cm^-1 at 530 nm. Complexes of the ML₂ type are formed.     

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.     

Spectrophotometric determination of nickel with 1-(1,2,4-triazolyl-3-azo)-2-naphthol with application to steel

Nickel(II) reacts with 1-(1,2,4-triazolyl-3-azo)-2-naphthol (TRAN) in aqueous 40% ethanol at pH 5 to form a red 1:2 complex having an absorption peak at 523 nm. The system conforms to Beer's Law in the range 0.2–2.8 ppm Ni(II). The molar absorptivity is 3.7 × 10⁴ l mol^-1 cm^-1. Various interferences can be avoided by extraction of the Ni(II)—TRAN complex into chloroform, which allows determinations of nickel in steels.     

Spectrophotometric Determination of Palladium(II) with n-Hydroxy-N,N-Diphenylbenzamidine and 1 -(2-Pyridylazo)-2-Naphthol

A spectrophotometric method to determine palladium(II) at trace levels is based on the extraction of palladium(II) as a binary complex with N-hydroxy-N,N′-diphenylbenzamidine (HDPBA) in chloroform at pH 5.0 ± 0.2. The complex shows maximum absorbance at 400 nm with molar absorptivity 6.4 × 10³ L mol^?1 cm^?1. The sensitivity of the Pd(II)-HDPBA complex was enhanced by the addition of l-(2-pyridylazo)-2-naphthol (PAN). The green coloured complex shows maximum absorbance at 620 nm with molar absorptivity 1.58 × 10⁴ L mol^?1 cm^?1. Sandell's sensitivity and the detection limit of the method are 0.0067 μg cm^?2and 0.1 μg Pd(II) mL^?1, respectively. Most common metal ions associated with palladium metal do not interfere. The effects of various analytical parameters on the extraction of the metal are discussed.     

Spectrophotometric Determination of Diphenadione Via its Metal Complexes

Abstract

Spectrophotometric procedure is described for the quantitative determination of diphenadione [2-(diphenylacetyl)-1,3-indandione], based on direct spectrophotometric measurements of the absorbances of its iron (III), iron (II) and cobalt (II), metal complexes at 488 nm, 505 nm and (334 nm, 372 nm), respectively. The drug reacts with metals in the ratio of 3:1 and 2:1 for iron (III) and for both iron (II) and cobalt (II) respectively. The obtained complexes have apparent molar absorptivities of 1.48 × 10³ 1 mol^?1 cm^?1, 0.714 × 10³ 1 mol^?1cm^?1 and (1.70 × 10³ 1 mol^?1cm^?1, 1.93 × 10³ 1 mol^?1cm^?1) for iron (III), iron (II) and cobalt (II) complexes, respectively. The procedure is suggested for the determination of 51–400 μg.ml^?1 diphenadione via the iron (II) complex and 35–170 μg.ml^?1 diphenadione via both cobalt (II) and iron (III) complexes. The suggested procedure has accuracies of 99.79 ± 0.67%, 99.64 ± 0.37% and (100.09 ± 0.53%, 99.99 ± 0.42%) for the metal complexes of iron (III), iron (II) and cobalt (II), respectively.     

Spectrophotometric determination of nickel with cyclohexylidine-ammonium 2-aminocyclohexylidene-1-cyclohexene-1-dithiocarboxylate

An (extraction)-spectrophotometric method is reported for the determination of nickel(II) with cyclohexylidineammonium 2-aminocyclohexylidene-l-cyclohexene-l-dithiocarboxylate. The violet 1:2 chelate is soluble in aqueous ethanolic or acetonic media at pH 6–9, or can be extracted into methyl isobutyl ketone. The molar absorptivity of the complex is about 2.5 × 10⁴ l mol^?1 cm^?1 at 550 nm.     

Sensitive spectrophotometric determination of La(III) with 1-(2-pyridylazo)-2-naphthol

A simple and sensitive method for spectrophotometric determination of lanthanum has been developed. At pH 9.6, in presence of 50% ethanol, lanthanum reacts with 1-(-2-pyridylazo)-2-naphthol (PAN) to form a red complex which has two absorption maxima, at 545 and 510 nm. The molar absorptivity at 545 nm is 0.55 × 10⁴ liters · mol^?1 cm^?1. On the other hand, lanthanum reacts with PAN in pure ethanol to form a red complex at 530 nm, with high molar absorptivity (8 × 10⁴ liters · mol^?1 cm^?1).     

Extraction—spectrophotometric determination of palladium(ii) with 2-nitroso-5-diethylaminophenol

An extraction—spectrophotometric determination of palladium(II) with 2-nitroso-5-diethylaminophenol is described. Complex formation and extraction of the complex with chloroform are possible with aqueous phases of about 2.5 M sulfuric acid. The molar absorptivity of the complex is 4.38 X 10⁴ l mol^-1 cm^-1 at 486 nm. Few of the common ions interfere at concentrations of 10^-4–10^-3 M; more than 10^-5 M Ir(IV), 10^-5 M W(VI), 5 × 10^-6 M Au(III) and 10^-6 M iodide cause negative errors. The method can be applied to the determination of palladium in catalysts for automobile exhaust purifiers.     

Analytical applications of 3-(2′-thiazolylazo)-2,6-diaminopyridine: Spectrophotometric determination of palladium

3-(2′-Thiazolylazo)-2,6-diaminopyridine reacts with palladium(II) in strongly perchloric acid media, to produce a blue 1:1 complex (λ_max = 665 nm, ? = 1.37 × 10⁴ liters · mol^?1 · cm^?1), which allows the spectrophotometric determination of 0.6 to 4.5 ppm of palladium. The method is applied to the determination of palladium in small samples of hydrogenation catalysts.     

Sensitive flotation—spectrophotometric determination of rhodium with malachite green

Two sensitive, precise spectrophotometric methods for the determination of rhodium with malachite green are proposed. The anionic rhodium complex with tin(II) chloride yields an ion associate with malachite green; on shaking the solution (in 6.5 M HCl) with benzene, the sparingly soluble ion associate (rhodium: malachite green =1:2) precipitates at the phase boundary. The precipitate is dissolved in a mixture of acetone and water (3 + 1). The molar absorptivity is 1.44 × 10⁵ l mol^l-1 cm^-1 at 627 nm. When test solutions (0.65 M HCl) are shaken with diisopropyl ether, an ion associate of a different composition is formed (rhodium :malachite green = 1:5) and the molar absorptivity is 3.4 × 10⁵ l mol^-1 cm^-1. Platinum, palladium and iridium interfere except in small amounts.     

Spectrophotometric studies on complexation reactions of some water-soluble 5-nitro-2-pyridylhydrazones with cobalt. Spectrophotometric and derivative spectrophotometric determination of trace cobalt with 2-benzimidazolyl-3-sulphophenylmethanone 5-nitro-2-pyridylhydrazone

The complexation reactions of four water-soluble hydrazones, 2-quinolyl-3-sulphophenylmethanone 5-nitro-2-pyridylhydrazone, 3-sulphophenyl-2-thiazolylmethanone 5-nitro-2-pyridylhydrazone (STNPH), 2-benzothiazolyl-3-sulphophenylmethanone 5-nitro-2-pyridylhydrazone and 2-benzimidazolyl-3-sulphophenylmethanone 5-nitro-2-pyridylhydrazone (BISNPH), with cobalt(II) were studied spectrophotometrically. These hydrazones react with cobalt(II) to form stable 1:2 (metal:ligand) complexes, except for STNPH, which forms a 1:1 complex, with high molar absorptivities. A sensitive and selective spectrophotometric method for the determination of cobalt with BISNPH has been developed. The cobalt(II)-BISNPH complex is formed quantitatively in the pH range 2.7–9.4 and oxidized rapidly to give the corresponding cobalt(III) complex with an absorption maximum at 517 nm. Beer's law is obeyed over the range 0.02–1.0 μg ml^?1 and the apparent molar absorptivity of the cobalt(III) complex is 6.65 × 10⁴ l mol^?1 cm^?1 at 517 nm. The method was applied to the determination of cobalt in iron and steel samples with satisfactory results. The sensitivity is increased 11-fold by use of second-derivative spectrophotometry.     

2-(8-quinolylazo)-4,5-diphenylimidazole — a sensitive extraction spectrophotometric reagent for mercury

Mercury(II) reacts with 2-(8-quinolylazo)-4,5-diphenylimidazole in aqueous solution; the complex can be extracted with chloroform or 1,2-dichloroethane at pH 4.5–9.5 to give a stable reddish-purple solution. The system conforms to Beer's law; the optimal range in chloroform is 0.05–2 ppm mercury (1-cm cells). Of 25 metal ions investigated, only copper and vanadium interfere seriously. The proposed method is exceptionally sensitive; the molar absorptivity in the chloroform extract is 7.3 × 10⁴ l mol^?1 cm^?1 at 580 nm; the Sandell sensitivity is 0.0027μg Hg cm^?2.     

Extraction and spectrophotometric determination of trace amounts of tin(II) with diphenylglyoxal bis(2-hydroxybenzoylhydrazone)

Diphenylglyoxal bis(2-hydroxybenzoylhydrazone) has been used as a sensitive reagent for the spectrophotometric determination of tin. This reagent forms an orange-yellow complex with stannous ion at pH 3.5–7.0 (λ_max = 455 nm, ? = 2.25 × 10⁴ liter mol^?1/cm^?1 while no reaction is observed with quadrivalent tin. The colored complex extracted into isobutyl methyl ketone has been used for the spectrophotometric determination of trace amounts of tin(II). The molar absorption in the organic solvent is 3.54 × 10⁴ liter mol^?1 cm^?1 and the compound shows its maximum absorbance at 455 nm. The interferences of foreign ions have been determined.     

Zero-Order and Third-Derivative Spectrophotometric Determination of Iron(III) with 4-(2-Pyridylazo)-Resorcinol in the Presence of N-Hexadecylpyridinium Chloride

Abstract

The complex formation reaction between iron(III) and 4-(2-pyridylazo) resorcinol(PAR) in the presence of various water soluble surfactants((N-hexadecylpyridinium chloride (HPC), poly(vinylalcohol)(PVA), sodium dodecylsulfate(SDS), sodium N-lauroylsarcosine(SL)) alone or in combination at weakly acidic media was systematically investigated. An improved and more sensitive spectrophotometric method for the determination of iron was proposed by zero-order and third-derivative spectrophotometry using the PAR-iron(III)-HPC ternary complex system at about pH 5.2. The calibration curve was rectilinear in the ranges of 0 – 15.0 μg iron(III) in a final 10-ml on the zero-order spectrophotometry. Also, upon the third-derivative spectrophotometry, Beer's law was obeyed in the range of 0 – 8.0 μg iron(III)/10 ml by measuring the distance between the absorbance peak(λ₁ = 527 nm) and the valley (λ₂ = 560 nm). The apparent molar absorptivity was 4.8 × 10⁴ 1 mol^?1 cm^?1 in zero-order spectrophotometry, and 1.36 × 10⁵ mol^?1 cm^?1 in third-derivative spectrophotometry. The effect of foreign ions was decreased within ½ – ¼-fold in comparison with the method in the presence of PVA without HPC. Especially, the third-derivative spectrophotometric method was sensitive and selective, and made possible to assay mixed sample solution containing iron(III) and copper(II), etc.     

Spectrophotometric Determination of Lead by Extraction of the Mixed-Metal Complex Pb(II)-Ca-Purpurin (1,2,4-Trihydroxyanthraquinone)

Abstract

Mixtures of Lead(II) and Ca(II) form with purpurin (P; 1,2,4-Trihydroxyanthraquinone) the mixed-metal-complex PbCaP₃, which is extracted with isobutyl methyl ketone (IBMK) at pH 7.8. The molar absorptivity of the complex is 2.8 × 10⁴ l.mol^?1.cm^?1 at 575 nm and its conditional extraction constant 2.5 × 10¹⁷ 1⁴.mole^?4. The use of this complex for the spectrophotometric determination of lead up to 40 μg has been investigated. The proposed procedure has been successfully applied to the analysis of this metal in different samples.     

Simultaneous spectrophotometric determination of binary mixtures of nickel,cobalt and vanadium with 3-(picolydene)benzenesulphonic acid 2-hydroxybenzoylhydrazone

The synthesis and characterization of a water-soluble reagent, 3-(picolydene)benzenesulphonic acid 2-hydroxybenzoylhydrazone, is described. The reagent is stable in aqueous media. The colour reations with nickel(II), cobalt(III) and vanadium(V) ions in slightly acidic solutions have molar absorptivities in the range 1.4–3.6 × 10⁴ l mol^?1 cm^?1. Simultaneous determinations of Ni, Co and V in binary mixtures are possible. Interference data are reported.     

p-Sulphobenzeneazo-4-(2,3-dihydroxy-5-chloropyridine) as a spectrophotometric reagent for vanadium in steels

Vanadium(V) reacts quickly with the reagent to form a water-soluble orange-red 1:2 complex (λ_max = 495 nm ; ? = 2.5 × 10⁴ l mol^-1 cm^-1). The complex is used to determine 0.04–1.5% vanadium in steels.     

Extractive spectrophotometric determination of nitrite in polluted waters

Nitrite is diazotised with p-nitroaniline in hydrochloric acid and coupled with 8-quinolinol in alkaline medium to give a purple azo dye (λ_max = 550 nm, ? = 3.88 × 10⁴ l mol^-1 cm^-1). Extraction of the dye into 3-methyl-1-butanol shifts the absorption maximum to 570 nm and improves the apparent molar absorptivity to 5.852 × 10⁴ l mol^-1 cm^-1. Beer's law is obeyed for 0.01–0.06 ppm nitrite. The Sandell sensitivity is 0.00078 μg cm^-2. The method is applicable to polluted waters.     

Spectrophotometric determination of iron(III) with chrome azurol s or eriochrome cyanine r and some cationic surfactants

Sensitive spectrophotometric methods for the determination of iron(III), based on ternary complexes with a triphenylmethane reagent, chrome azurol S (CAS) or eriochrome cyanine R (ECR), and cetyltrimethylammonium (CTA) or cetylpyridinium (CP) ions, are described. For the system Fe—CAS—CTA, the molar absorptivity is 1.35 × 10⁵ l mol^-1 cm^-1 at 645 nm; for Fe—ECR—CTA it is 1.28 × 10⁵ l mol^-1 cm^-1 at 635 nm. Maximum absorbance is attained (at about pH 4) when the molar ratio (to iron) or CAS or ECR is about 20 and that of CTA or CP is 60–80. Citrate, tartrate, oxalate and EDTA interfere. Interference by metals (e.g. Be, Al, Ga, In, Sc, Zr, Th) can be eliminated by preliminary extraction of iron(III) as thiocyanate complex. The method was successfully applied to determining traces of iron in analytical-grade sodium hydroxide.     

Complexing Properties of Uranium and Lanthanoids With 4-(2-Thiazolylazo)-6-Chlororesorcinol

Abstract

4-(2-Thiazolylazo)-6-chlororesorcinol (TAR-Cl) reacts sensitively with uranyl(II) and lanthanoids(III), and forms reddish-brown 1:1 and 1:2 complexes. The complexing behaviors were examined spectrophotometrically. The absorption maxima of the complexes are focused near 553 nm and the optimum pH for complexation lies between 6.5–8.8. Beer's law holds up to about 2 × 10^?5 mol 1^?1, with a molar absorptivity of 3.00 × 10⁴ 1 mol^?1 cm^?1 for uranium and 6 × 10⁴ 1 mol^?1 cm^?1 level for each lanthanoid. The absorptivities are increased with the atomic number, especially in light lanthanoids, that are correlative both to the lanthanoid contraction and the basicity of ortho hydroxyl group in the resorcinol ring, but such effects are not clearly recognized in heavy lanthanoids. Effect of masking agents was also examined, and uranium could be determined selectively in the presence of lanthanoid mixtures by the addition of CyDTA.