Selective Spectrophotometric Determination of Palladium (II) With 2-(5-Bromo-2-Pyridylazo)-5-(Diethylamino)-Phenol

Abstract

A spectrophotometric study of the Pd(II) complex of a reagent 2-(5-Bromo-2-Pyridylazo)-5-(diethylamino)-Phenol (5-Br-PADAP) is presented. A violet complex is formed at pH 3.53, and shows maximal absorbance at 585 nm with molar absorptivity of 3.86 × 10⁴ 1. mol^?1 cm^?1. Beer's law is obeyed up to 50 μ of Pd(II). The method offers the advantages of simplicity, high precision, requires no extraction and is very selective, where 5.0 mg Pt(VI) and 0.3 mg Au(III) ions do not interfere.     

Environmental Analysis of Thorium (IV) by Extractive Separation with N-p-Methoxyphenyl-2-furylacrylohydroxamic Acid and Spectrophotometric Determination with 4-(2-Pyridylazo) Resorcinol

Abstract

Thorium (IV) was separated from several anions and cations commonly associated with it in environmental samples by liquid-liquid extraction with N-p-methoxyphenyl-2-furylacrylohydroxamic acid (MFHA) into chloroform at pH 3.6–5.5. The metal was then back-extracted into aqueous media containing 1.8–2.2 M HCl and determined spectrophotometricall) at 500 nm (? = 3.9 × 10⁴ 1 mol^?1 cm^?1) with 4-(2-pyridylazo) resorcinol [PAR]. The method was successfully applied to the analysis of thorium in coal fly ash, monazite, uranium-thorium ore, animal tissue, plant tissue, and natural waters. MFHA and PAR were chosen from thirteen hydroxamic acids and nine pyridylazo reagents, as the reagent combination that provided the maximum selectivity and sensitivity.     

钯的PAR-氯化四苯鉮的萃取光度法测定

本文报道了钯与4-(2-吡啶偶氮)间苯二酚(PAR=H_2R,下同)和四苯钟离子形成离子缔合物的化学条件,经氯仿萃取后,建立了一种测定微量钯的萃取光度法。萃取的最佳pH为4.4,络合物的化学式为[(C_6H_5)_4As~+,PdClR~-],其最大吸收峰波长为532nm,表观摩尔吸光系数e_(532)=3.3×10~4L·mol~(-1)·cm~(-1),10mL萃取液中钯量在0～25μg内遵守比耳定律。方法简便,选择性好,用于催化剂中钯的测定,结果满意。     

Trace Analysis of Vanadium in Environment as its Ternary Complex with N-p Methoxyphenyl-2-Furylacrylohydroxamic Acid and 3-(o-Carboxyphenyl)-1-Phenyltriazine-N-Oxide

Abstract

A method is presented for the highly sensitive, selective, and rapid determination of vanadium (V) at sub-microgram levels in rocks, animal tissues, plant tissues and natural waters. The method is based on the selective extraction of vanadium (V) from strongly acidic (3-8 M hydrochloric acid) medium with solution of N-p-methoxyphenyl-2-furylacrylohydroxamic acid (MFHA) in chloroform. The reddish-violet extract (molar absorbance 8.6x10³ 1 mole^?1 cm^?1 at λ max 545 nm) is then equilibrated with 3-(o-carboxyphenyl)-1-phenyltriazine-N-oxide (CPPTNO) at pH = 1.5. The resulting ternary complex has enhanced colour (molar absorbance 1.4 × 10⁴ 1 mole^?1 cm^?1 at Λ max 450 nm). The ternary system obeys Beer's Law at 450 nm over the range 0-18 μ g/ml of vanadium. The extraction system achieves 20-fold enrichment of vanadium and enables the determination of the metal down to parts per billion (ng 1^?1) levels. The method tolerates the presence of a large number of anions and cations which are normally present with vanadium in rocks, plant tissues, animal tissues and natural waters. The applicability of the method was tested by the analysis of vanadium in these matrices. MFHA was selected from nine hydroxamic acids as it provided maximum sensitivity and selectivity.     

显色剂2-(5-羧基-1,3,4-三氮唑偶氮)-5-二乙氨基苯甲酸与钯(Ⅱ)的显色反应研究

研究了显色剂2-(5-羧基-1,3,4-三氮唑偶氮)-5-二乙氨基苯甲酸(CTZDBA)与钯(Ⅱ)的显色反应。结果表明,Pd(Ⅱ)与CTZDBA生成稳定的1∶2的紫红色配合物,其最大吸收波长为548 nm,配合物的表观摩尔吸光系数为9.32×104L.mol-1.cm-1,Pd(Ⅱ)质量浓度在0.08~0.8 mg/L范围内符合比耳定律。该方法可不经分离直接测定钯碳催化剂和钯纳米碳催化剂中的微量钯,测定结果与原子吸收法(AAS)基本相符。     

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.     

Kinetics of Complexation of Uranium with 2-(5-Bromo-2-Pyridylazo)-5-(Diethylamino) Phenol (Br-PADAP) in a 1:1 Water-Ethanol Medium

2-(5-Bromo-2-pyridylazo)-5-(diethylamino) phenol (Br-PADAP) forms a 1:1 complex with the uranyl ion in the presence of sulphosalicylic acid, which acts as stabilizer for this complex in the triethanol amine/perchloric acid buffer system. A change in the stoichiometry of the complex was seen at pH<5. Kinetic measurements were carried out using stopped-flow spectrophotometer in the presence of an excess concentration of U(VI) in the pH range 6.5 to 8. The dependence of the pseudo-first-order rate constant, k(obs), on the concentrations of U(VI), ligand and hydrogen ion showed that Br-PADAP reacts with UO₂(OH)⁺ to form an intermediate species (equilibrium constant = 1.28×10⁴mol.dm⁻³) that then rearranges (rate constant = 5.6×10⁻²s⁻¹) to form the product species. UO₂(OH)⁺ is present in equilibrium with the unreactive species UO₂(OH)₂, as well as with the unreactive sulfosalicylic acid complex.     

Analysis of Metal Ions in Environmental Samples - III Synergistic Determination of Vanadium (V) As its Mixed Complex with N-0-Methoxyphenyl-2-Thenohydroxamic Acid and 3-(0-Carboxyphenyl)-1-Phenyltriazine-N-0Xide

Abstract

A highly sensitive, selective, and rapid method for the spectrophotometry determination of vanadium(V) at trace levels is described. The method is based on the selective extraction of vanadium(v) from strongly acidic (3–6 M hydrochloric acid) met ium with solution of N-0-methoxyphenyl-2- thenohydroxamic acid (0MTHA) in chloroform. The extract is then equilibrated with 3-(0-carboxyohenyl)-1-phenyltriazine-N-oxide(CPPTNO) at pH ? 1.5 and the resulting colour is measured at 445 nm. The colour system obeys Beer's law over the range 0–20 -μg/ml of vanadium; the molar absorptivityat the wavelength of maximum absorption (445 nm), and the Sandell sensitivity of the method are 1.1 × 10⁴1. mole^?1 cm^?1 and 0.005 μg/ml respectively.     

4, 5-二溴苯基荧光酮光度法测定微量钯

研究了在十二烷基磺酸钠存在下,Pd(Ⅱ)与4,5 二溴苯基荧光酮的显色反应.试验表明,在pH6 3醋酸 醋酸钠缓冲溶液中,Pd(Ⅱ)与试剂形成1∶4的暗黄色配合物,配合物的最大吸收峰位于376nm波长处,表观摩尔吸光系数ε为1 06×105L/(mol·cm).Pd(Ⅱ)含量在0～12μg/10mL范围内符合比尔定律.所拟方法用于钯催化剂和钯矿样中微量钯的测定,结果满意.     

Selective Extractive Spectrophotometric Determination of Palladium (II) with Di-2-Pyridyl Ketone 2-Pyridyl-Hydrazone (DPPH)

Abstract

Palladium (II) reacts with DPPH in slightly acid medium to form a red colored complex stable in presence of EDTA and extractable into chloroform.

These properties of the Pd(II)-DPPH complex were used for the selective extractive spectrophotometric determination of palladium(II) in presence of several tested cations.     

Synthesis and Spectrophotometric Studies of 2-(1, 3, 4 -Triazolylazo) -5-Diethylamino Phenol and 2-(5-Carboxy-1, 3, 4-Triazolylazo) -5- Diethylamino Phenol

Inasearchfornewsensitiveandselectiveorganicreagents,athoroughstudyofsomeofthequinolylazo,pyridylazocompoundshasbeenreported'-'.Buttriazolylazocompoundshavenotbeenstudied.Inthispapef,2-(l,3,4-triazolylazo)-5-diethyIaminophenol(TZAPN)and2-(5-carboxy-l,3,4-triazoiylazo)-diethyIaminophenoI(CTZAPN)wereprepared,theconditionsofthisreactionwithcobaltwerestudied.Itwasfoundthatthereagentshadhighsensitivityandselectivityinthedeterminationofmicrogramamountsofcobaltundertheconditionsestablished.Thest…     

新试剂2-(5-硝基-2-吡啶偶氮)-5-二甲氨基苯甲酸分光光度法测定微量钴

本文报道用新试剂2-(5-硝基-2-吡啶偶氮)-5-二甲氨基苯甲酸分光光度法测定微量钴。配合物的表观摩尔吸光系数为1.31×10~5L·mol~(-1)·cm~(-1),Co∶5-NO_2-PAMB=1∶2,Co浓度在0～14μg/25mL范围内服从比耳定律。用于金属有机化合物中微量钴的测定,结果与理论值相符。     

双波长分光光度法测定微量铜

报道了以５－（５－硝基－２－吡啶偶氮）－２－４－二氨基甲苯（５－ＮＯ２－ＰＡ－ＤＡＴ）为显色剂,应用双峰双波长光度法测定铜（Ｉ）的新方法。实验结果表明,在ｐＨ４．０￣ｐＨ６．０的乙酸－乙酸钠缓冲溶液中和盐酸羟胺和乙醇存在下,铜（Ｉ）可与试剂形成稳定的１：２红色配合物。     

Synergistic Spectrophotometric and Atomic Absorption Spectrometric Analysis of Zinc in Alloys and Environmental Samples with N-p-MEthoxyphenyl-2-Furylacrylohydroxamic Acid and Pyridylazo Reagents

Abstract

Zinc (II) was selectively extracted from aqueous solutions of pH 7.8–8.5 into chloroform with N-p-methoxyphenyl-2-furylacrylohydroxamic acid (MFHA). 1-(2-pyridylazo)-2-naphthol (PAN) or 2-[(5-nitro-2-pyridyl)azo]-1-naphthol (NPAN) were added to the extract to form intensely coloured ternary complexes measurable spectrophotometrically at 550 nm (? = 6.03 × 10⁴ 1 mol^?1 cm^?1) and 625 nm (? = 8.15 × 10⁴ mol^?1 cm^?1) respectively. For atomic absorption spectrometric analysis, methyl isobutyl ketone (MIBK) was used as extracting solvent instead of chloroform and the zinc-MFHA-MIBK extract was aspirated directly into an air-acetylene flame. The absorbance was measured at the 213.9 nm resonance line with a detection limit of 0.05 ppb, which was significantly better than the limit of 1.0 ppb achieved for zinc previously with flame AAS. The method tolerated a large number of anions and cations normally occurring with zinc in environmental samples, and was applied to the trace analysis of zinc in alloys, coal, plant tissues, animal tissues and natural waters. The combinations of MFHA and PAN/NPAN were chosen from eleven hydroxamic acids and nine pyridylazo reagents as detailed in the paper.     

Zero-Crossing Derivative Spectrophotometric Determination of Mercury(II) And Palladium(II) with 5-(3,4-Methoxyhydroxyphenylmethylene)-2-thioxo-1-3-thiazolidine and Cetyltrimethylammonium Bromide

Abstract

A method is proposed for the simultaneous determination of mercury(II) and palladium(II) by first-derivative spectrophotometry based on the absorption spectra of their complexes with 5-(3,4-Methoxyhydroxyphenylmethylene)-2-thioxo-1,3-thiazolidine [5-(3,4-methoxyhydroxybenzylidene) rhodanine]. Zero-crossing measurement technique is found suitable for the measurement of the first-derivative value at the specified wavelengths. Mercury(II) (0.4-1.4 μg ml^?1) and palladium(II) (0.08 - 1.8 μg ml^?1) in different ratios have been determined simultaneously. A critical evaluation of the proposed method is performed by statistical analysis of the experimental data.     

Rapid and Sensitive Spectrophotometric Determination of Hafuium(IV) With 2-(5-Bromo-2-Pyridylazo)-5-Diethylaminophenol

Abstract

Hafnium(IV) reacts with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in the pH range 3.3–11.0 to yield a sparingly soluble red-coloured chelate that can be dissolved with Triton X-100. Effect of initial pH of metal ion and order of addition of reagents was studied in detail. The 1:3 complex adheres to Beer's law over the concentration range 0.02–1.12 μg/ml of Hf(IV), has a molar absorptivity 1.33x10⁵ 1 mol^?1cm^?1, Sandell sensitivity 1.3 ng cm^?2, formation constant (log K) 11.94 and the method had a relative standard deviation of ± 1.5%. Effect of 60 diverse ions on the determination of hafnium(IV) was studied. This fairly selective method is the most sensitive so far reported for the spectrophotometric determination of hafnium(IV).     

Non-Extractive Simultaneous Spectrophotometric Determination of Trace Quantities of Palladium(II) and Tungsten(VI)

A second order derivative spectrophotometric method has been developed for the simultaneous determination of Palladium(II) and Tungsten(VI) using 3,4-dihydroxybenzaldehyde isonicotinoylhydrazone (3,4-DHBINH) as a new complexing agent. The Pd(II) reacts with 3,4-DHBINH in the pH range from 3 to 7 to form green colored solution. The absorbance calibration curves were constructed for palladium(II) at 362 nm (0.53～6.40 μg/ml) and tungsten(VI) at 374 nm (0.92～11.40 μg/ml). The metal ions interfere with each other in determination of zero order as well as the first order spectrophotometry. The optimum condition for maximum color development and other analytical parameters were evaluated. The method was applied successfully for the determination of palladium in hydrogenation catalyst and tungsten in industrial waste water samples.     

Synthesis and Spectrophotometric Studies of 2-(2-Imidazolylazo)-5- Dicthylamino Phenol

Inasearchfornewsensitiveandselectiveorganicreagents,athoroughstudyofslomeofthequinolylazo,pridylazocompoundshasbeenreported.'-'Buttriazolylazoandimidazolylazocompoundshavenotbeenstudied.Inanearliespaper,'wehavereportedthesynthesisandspectrophotometricstudiesof2-(l,3,4-triazolylazo)-5-diethy\phenoland2-(5-carboxy-l,3,4-triazolylazo)phenol.Inthispaper,2-(2imidazolylazo)-5-diethylaminophenol(IZAPN)wasprepared,theconditionsofitsreactionwithcobaltwerestudied.Itwasfoundthatthereagenthadhighsensiti…     

Simultaneous First Derivative Spectrophotometric Determination of Palladium and Nickel Using 2-(2-Thiazolylazo)-5-Dimethylaminobenzoic Acid as an Analytical Reagent

 A simple, rapid, selective, sensitive and economical method has been developed for the simultaneous determination of trace amounts of palladium and nickel in aqueous methanolic medium using 2-(2-thiazolylazo)-5-dimethylam inobenzoic acid as an analytical reagent by first derivative spectrophotometr y. Palladium is determined by measuring base to peak distance at λ=695.0 nm while nickel is estimated by zero crossing method in the mixture. The linearity is maintained between 0.12–1.75 μg mL⁻¹ for palladium and 0.07–1.60 μg mL⁻¹ for nickel in the pH range 2.8–7.2 and 3.4–8.8 respectively. Seven replicate determinations of 1.0 μ g mL⁻¹ of palladium and 0.8 μg mL⁻¹ of nickel in a mixture give a mean signal height of 0.391 for Pd and 0.541 for Ni with relative standard deviations of 0.9% and 1.2%, respectively. The sensitivity of the proposed method is 0.391 (dA/dλ)/(μg mL⁻¹) for palladium and 0.685 (dA/dλ)/(μg mL⁻¹) for nickel. Various parameters have been optimised for the simultaneous determination of palladium and nickel in various complex samples. Received March 30, 1999. Revision November 25, 1999.