Spectrophotometric determination of palladium by adsorption of its n-butyl xanthate complex on microcrystalline naphthalene

A new reliable method for the spectrophotometric determination of trace amounts of palladium after adsorption of its n-butyl xanthate complex on microcrystalline naphthalene is developed. Palladium reacts with this reagent to form a colored water insoluble complex which can be quantitatively adsorbed on naphthalene in the pH range of 3.8 – 8.4. The mixture of the complex and naphthalene is dissolved in chloroform and the trace amount of palladium is determined spectrophotometrically. It has an adsorption maximum at 385 nm. Beer's law holds in the concentration range of 2.5–105.0 μg of palladium in 10 ml of chloroform. The molar absorptivity of the complex is found to be 1.319 × 10⁴ liters mol cm⁻¹, while the Sandlle's sensitivity is 0.008 μg cm⁻² for palladium at 385 nm. Samples containing 25 μg of palladium give a mean absorbance of 0.310 with a standard deviation of 0.0027. The effect of experimental variables such as pH, amount of reagent, aqueous phase volume, and diverse ions have been examined. The method has been applied to the determination of palladium in some alloys.     

A highly sensitive spectrophotometric determination of palladium with chromal blue g and cetyltrimethylammonium chloride

A new spectrophotometric method for the determination of palladium with chromal blue G (Color Index 43835) and cetyltrimethylammonium chloride is described. The sensitivity of the color reaction between palladium and chromal blue G is greatly increased in the presence of cetyltrimethylammonium chloride. The palladium complex has maximal absorbance at pH 3.2–3.8 and at 670 nm. Beer's law is obeyed over the range 0.08–1.4 p.p.m. palladium; the molar absorptivity is 1.01 · 10⁵ l mol^-1 cm^-1 at 670 nm and the sensitivity is 1·10^-3 μg Pd cm^-2. The mole ratio of palladium and chromal blue G in the complex in the presence of cetyltrimethylammonium chloride is 1:3. Only scandium interferes when sodium fluoride is used as masking agent.     

Liquid-liquid extraction and spectrophotometric determination of palladium with 2-mercaptobenz-amide

2-Mercaptobenzamide (MBA) was investigated as a reagent for the extraction of palladium. The palladium complex of MBA was extracted into tributyl phosphate (TBP). The pK_a of the ligand was 5.45 with the stability constant of the palladium complex β₂=10^7.1. The composition of the complex in TBP was Pd:MBA:TBP=1:2:2. Addition of sodium chloride accelerated the rate of extraction. Various interfering ions could be masked with EDTA; Ag(I), Au(III), Os(VIII), Se(IV), Te(IV) etc. interfered. The molar absorptivity was 1.59×10⁴ l mol^?1 cm^?1; 1–35 μg Pd could be determined at pH 6.0.     

Isonitroso-4-Methyl-2-Pentanone for Solvent Extraction and Spectrophotometric Determination of Palladium (II) at Trace Level

Abstract

Isonitroso-4-methyl-2-pentanone (HIMP) is proposed as a new reagent for extraction and photometric determination of Pd(II). The reagent forms a yellow complex with palladium in the pH range 4.0-5.0. The complex extracted into chloroform was measured at 330 nm. The molar absorptivity was found to be 5.37 × 10³ 1 mol^?1 cm^?1 and Sandell's sensitivity 20 ng cm^?2 Beer's law was obeyed over the concentration range 0.1-10.0 μg/ml of palladium. The method is applicable for palladium estimation in Ores and catalysts.     

Prochlorperazine bismethanesulfonate as a new reagent for the spectrophotometric determination of palladium

A simple, rapid, and selective method for the determination of palladium is described. The orange-red palladium(II)-prochlorperazine bismethanesulfonate complex in the presence of hydrochloric acid-sodium acetate buffer exhibits maximum absorbance at 480 nm with a molar absorptivity of 4.32 × 10³ liters mol^?1 cm^?1. The sensitivity of the reaction is 24.62 ng cm^?2. The system obeys Beer's law over the concentration range 0.4–20 ppm of palladium with an optimum concentration range of 1–19 ppm. The apparent stability constant of the complex is found to be log K = 5.3 ± 0.1 at 27 °C. The effects of pH, time, temperature, order of addition of reactants, reagent concentration, and interferences from various ions are reported. The proposed method offers the opportunity to carry out the determination at room temperature without the need for an extraction step. The method is also found to be suitable for the determination of palladium in jewelry alloy.     

Spectrophotometric Determination of Palladium with Methylthymol Blue

A new, sensitive spectrophotometric method for the determination of palladium(II) with methylthymol blue has been developed. The palladium methylthymol blue complex has an absorption maximum at 530 nm. The colour reaction has a sensitivity of 0.005 µg of palladium/cm² and obeys Beer's Law over the range 0.4 to 3.24 ppm of palladium. The effects of concentration of perchloric acid, reagent, heating, stability of colour and diverse ions have been investigated. The ratio of metal: ligand in the complex is 1:1 and the formation constant was calculated to be 1.18×10⁴.     

Microdetermination of palladium based on formation of ternary complex of palladium with pyrogallol red and cetylpyridinium bromide

A new spectrophotometric method was employed for the determination of microamounts of palladium(II) based on the ternary complex formation with pyrogallol red and cetylpyridinium bromide. A blue green ternary complex, whose molar absorptivities is 22500 mol^?1 cm^?1 at 650 nm, is formed. Composition (PdPGRCP₃) of the ternary complex was established by continuous variation and mole ratio methods. Beer's law range (0.1–8.5 ppm of Pd) and Sandell's sensitivity (0.001 γ/cm²) were evaluated. The conditional stability constant value (logK = 24.35) was determined by Prakash et al. 's method. A detailed study was made for the determination of microamounts of palladium in the presence of platinum metals and several other cations and anions.     

Analytical study of the phenyl-2-pyridyl ketone azine-palladium system. Photometric determination of palladium

Phenyl-2-pyridyl ketone azine reacts with palladium(II) to produce a yellow 1:1 complex (λ_max = 425 nm, ? = 10.4 × 10³M^?1 cm^?1 in aqueous ethanolic solution) and a red-violet 3:1 complex (λ_max = 530?540 and 380?390 nm). The yellow complex in aqueous ethanolic solution has been used for the spectrophotometric determination of trace amounts of palladium. The method has been applied to the determination of palladium in some catalysts and one mineral.     

2-(4-Toluenesulphonamido)aniline as an analytical reagent : The nature of the reaction with copper(II)

2-(4-Toluenesulphonamido)aniline,TSA, was examined to evaluate the claim that it is a specific gravimetric reagent for copper(II) and to see if the application of the reagent could be extended. The nature of the reaction and complexes was investigated by potentiometry, solvent extraction, spectrophotometry, polarography and mass spectrometry. A 1:2 copper: TSA complex formed at pH 6 (K₁=10^19.11 in 50% (v/v) aqueous dioxane) is suitable for the gravimetric determination, as previously reported. A violet complex (λ_max. 550 nm, ε=6620) of uncertain composition is formed at pH 10–11 and may be used for the spectrophotometric determination of copper. The centres of chelation have been deduced from the infrared spectra of the complex and reagent and the causes of the selectivity are discussed.     

Spectrophotometry Determination of Molybdenum with N-Cyanoacylacetaldehyde Hydrazone

N-cyanoacylacetaldehyde hydrazone (CAAH), which is a laboratory synthetic reagent, is proposed as a new reagent for spectrophotometry determination of microamounts of molybdenum at λ_max 790 nm. The reagent forms 1:1 blue coloured complex with molybdenum (VI) in phosphoric acid solution. The stable blue colour is obtained finally after changing from yellow to green. The colour development depends on temperature, time and concentration of phosphoric acid. This reagent is applied for the determination of molybdenum in steel alloys and the results are satisfactory.     

Studies on pollutants: A new reagent for the detection of fluoride

A new solid analytical reagent is reported for the detection and semiquantitative determination of traces of fluoride. A blue (λ_max 590 nm) trypan blue dye is liberated from an insoluble zirconium-trypan blue complex by the action of fluoride in dilute acetic acid medium. The detection limit is 0.8 ppm and the range of semiquantitative determination is 0.8 to 8 ppm. The method is simple and can be conveniently used for field detection of fluoride in polluted waters.     

Palladium(II) extraction with 1-{[2-(2,4-Dichlorophenyl)-4-propyl-1,3-dioxolan-2-yl]-methyl}-1H-1,2,4-triazole from nitric acid solutions

Palladium(II) extraction from nitric acid solutions with 1-{[2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolan-2-yl]-methyl}-1H-1,2,4-triazole in toluene is studied. The reagent efficiently extracts palladium(II) from 0.2–6 M HNO₃ by a coordination mechanism yielding the complex Pd₂(NO₃)₄ S ₃ in the organic phase. The reagent can be used for selective separation of palladium(II) from nickel(II), copper(II), and iron(III) in the specified aqueous phase acidity range.     

Equilibrium and kinetic studies of the Fe(III) complex formation with glycinehydroxamic acid

Spectrophotometric methods were utilized for stability constant determinations of the Fe(III) interaction with glycinehydroxamic acid (GX) at I = 0.15 M NACl and T = 25°C. Program SQUAD II was used to assess the absorbance data in the wavelength range 300–520 nm. Four constants were determined for 1:1:1, 1:1:0, 2:1:1 or 3:1:3 and 2:1:0 complex species in the pH range 1.0–7.5. The kinetics of the interactions of Fe(III) with GX were also studied in the pH range 1.0–3.0 by the stopped flow method. The observed rate constant at a given pH was k_obs = _A + BT_GX. The parameters A and B are functions of pH in the range 1.7–3.0 and only A is a function of pH in the range 1.0–1.7. The mechanism of complex formation was discussed in the light of the experimental results and the equilibrium study. It has been concluded that FeOH²⁺ is the reactive species in the complex formation of FeGXH³⁺ species while Fe(OH)₂⁺ is the reactive species in the complex formation of FeGX²⁺ species.     

o-Hydroxyacetophenone thiosemicarbazone as a reagent for the rapid spectrophotometric determination of palladium

o-Hydroxyacetophenone thiosemicarbazone has been synthesized and employed as a new reagent for the spectrophotometric determination of palladium(II), which forms two complex species with it in aqueous dimethylformamide at pH 6.0, these having 1:1 and 1:2 metal-ligand ratios. The Job and molar-ratio plots have an unusual shape that is due to the stepwise conversion of the 1:1 complex into the 1:2 species. The molar absorptivity at 370 nm is 9 x 10(3) l.mole(-1).cm(-1). Beer's law is obeyed over the range 0.42-10.6 mug/ml palladium.     

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.     

Spectrophotometric Determination of Palladium by the New Chromogenic Reagent N-Butyl - N'-(Sodium P-Aminobenzenesulfonate) Thiourea

Abstract

A highly sensitive spectrophotometric method for determination of palladium by the new chromogenic reagent (BPT) has been developed. In the presence of cetyltrimethylammonium bromide(CTMAB), palladium reacts with BPT to form a stable yellow complex in HAc-NaAc buffer solution of pH 4.6-5.6 at 294.4 nm with a molar absorptivity of 2.46 x 10⁵ l mol^?1 cm^?1. The method is simple, rapid and sensitive. Trace amounts of palladium in mineral and catalyst samples have been satisfactorily determined by the method.     

Rapid and sensitive spectrofluorimetric determination of trace amount of Cr(III) with o-vanillin-8-aminoquinoline

A novel fluorescent reagent o-vanillin-8-aminoquinoline(OVAQ) was synthesized, and its infrared spectrum, elemental analysis and acid-base dissociation constants were obtained. The fluorescent reaction of this reagent with Cr(III) was studied. In acetonitrile-water (1:1, (v/v)) medium of pH 6.00, Cr(III) could react with fluorescent reagent OVAQ (λ_ex/em=280/314 nm) to form a 1:1 non-fluorescent complex. The linear range of the spectrofluorimetric method proposed was from 8.2 to 130 μg l⁻¹, and the detection limit was 2.5 μg l⁻¹. The interferences of 25 foreign ions were also studied. This method could be easily performed and was successfully applied to the determination of Cr(III) and total chromium in domestic and industrial waste water samples.     

Spectrophotometric determination of uranium(VI) with 7-chloro-8-hydroxyquinoline-5-sulphonic acid

Uranium(VI) and 7-chloro-8-hydroxyquinoline-5-sulphonic acid form a 1:2 complex with λ_max at 355 nm, in aqueous medium at pH 6.6. A procedure for accurate spectrophotometric determination of hexavalent uranium with 7-chloro-8-hydroxyquinoline-5-sulphonic acid has been described. Optimum conditions, including the effect of pH, time, temperature, order of addition of the reagents, and excess of the reagent have been studied. Range for adherance to Beer's law, effective photometric range, molar absorptivity, and Sandell sensitivity have also been reported as 1–38 ppm, 5.7–28.5 ppm, 6575 and 0.036 μg of uranium/cm² respectively. The method has been compared with some other methods for determination of uranium spectrophotometrically, with regard to their sensitivities. Interferences of various ions in the measurement of the color have been investigated, and the tentative structure of the colored species in solution has been proposed.     

Application of non-steroidal anti-inflammatory drugs for palladium determination

A highly sensitive spectrophotometric method for palladium determination using piroxicam and tenoxicam as new chromogenic reagents has been developed. In the presence of sodium lauryl sulfate (SLS), palladium reacts with piroxicam (PX) or tenoxicam (TX) to form stable yellow orange complexes in an acetate buffer solution of pH 5.0 at 424 nm and 426 nm with molar absorptivity of 7.16 × 10⁴ L mol⁻¹ cm⁻¹ and 1.20 × 10⁵ L mol⁻¹ cm⁻¹, respectively. Sandell sensitivity, detection, and quantitation limits were also calculated. Optimum conditions were evaluated considering pH, reagent concentration, time, temperature, and surfactant concentration. The complex system conforms to Beer’s law over the range of 0.07–1.28 μg mL⁻¹ palladium. The stoichiometric ratio and stability constant were also evaluated. Tolerance limits of many cations and anions were determined. Finally, the proposed method was applied successfully in the determination of palladium in jewellery, anode mud, synthetic mixtures, catalysts, and alloy samples.     

Analytical application of arsenazo III to the spectrophotometric determination of palladium: Preliminary investigation of the complex formation in the arsenazo III-Pd (II)--H2O system

The reaction of arsenazo III with palladium(II) was investigated. Complex species of types M₂L and ML are formed at pH 2–4; the complex M₂L shows a very sharp maximum at 630 nm while the ML species shows maximum absorption at 620 nm. The molar absorptivities of the complexes are 4.2(±0.1) · 10⁴ and 1.6(±0.2) · 10⁴ respectively. The complex ML conforms to Beer's law at 620 nm in the range 10–250 μg Pd(II)/50 ml. The sensitivity of the reaction of Pd(II) with arsenazo III is about the same as that of a new reagent, palladiazo, but the latter is more selective for Pd(II). Serious interferences might be caused by UO₂²⁺, U⁴⁺, Th⁴⁺, Cu²⁺, Ni²⁺, Co²⁺, Y³⁺ and the rare-earth elements.