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.     

Chlorophosphonazo-m-NO2, a new reagent for the spectrophotometric determination of cerium sub-group rare earth elements in the presence of yttrium sub-group elements

The synthesis of chlorophosphonazo-m-NO₂ is described. Cerium sub-group rare earth elements can be determined in the presence of 10–40 fold amounts of yttrium sub-group elements when the latter are masked by oxalic acid at pH 1.6. Under the experimental conditions employed, the apparent molar absorptivities of lanthanum and cerium at 666 nm are 9.5 × 10⁴ and 9.3 × 10⁴ l mol^-1 cm^-1, respectively. Beer's law is obeyed for 0–12 μg of lanthanum or cerium in 25 ml of solution. The coefficients of variation for La and Ce are 0.37% and 0.92%, respectively.     

Spectrophotometric determination of osmium with phthalimide dithiosemicarbazone by means of complex formation and catalytic reactions

Phthalimide dithiosemicarbazone forms a 1:1 complex with osmium at pH 3.3–4.5 (?₄₅₀ = 1.3 · 10⁴ l mol^?1 cm^?1 ) which is applied to the photometric determination of osmium; Beer's law is obeyed for the range 1–12 μg Os ml^?1. The oxidation of the reagent with cerium(IV) is catalyzed by osmium(VIII), and this reaction allows a more sensitive procedure for the determination of osmium; the calibration curve is linear over the range 0.05–0.4 μg Os ml^?1. The interferences in both procedures are described.     

Spectrophotometric determination of vanadium with n-benzoyl-o-tolylhydroxylamine

N-Benzoyl-o-tolylhydroxylamine is shown to provide a virtually specific reagent for the spectrophotometric determination of vanadium. The reddish-violet complex formed with the reagent in 4–8 N hydrochloric acid after extraction with chloroform shows absorption maxima at 510 mm, and obeyes Beer's law from 0.5 to 10 μg with an optimum range of 2–10 μg; the percent relative error is 2.7. The sensitivity is 0.0108 μg V/cm². The complex contains the metal and the reagent in a ratio of 1:2 and the dissociation constant is of the order of 10^-9.     

Formation and reduction of molybdothorophosphoric acid

The stoichiometry of formation and the kinetics of reduction of molybdothorophosphoric acid in nitric acid solutions were studied spectrophotometrically. The Mo:Th:P ratio in the complex is 12:1:1, assuming that Mo(VI) exists in acid solutions as a dimer. The ternary heteropoly acid is more stable and is reduced more slowly to the heteropoly blue than 12-molybdophosphoric acid. The kinetics of the first stages of the reduction were studied with ascorbic acid and p-methylaminophenol as reductants. The experimental rate law is in good agreement with a mechanism involving an equilibrium step in formation of the heteropoly acid followed by the reduction. Under recommended conditions, Beer's law was obeyed up to 40 mg l^?1 thorium.     

Extraction-photometric determination of uranium(IV) with chlorophosphonazo-III

A sensitive spectrophotometric method has been developed for the determination of uranium. The uranium(IV)-chlorophosphonazo-III complex is extracted into 3-methyl-1-butanol from 1.5–3.0 M hydrochloric acid solution. Maximal absorbance occurs at 673 nm and Beer's law is obeyed over the range of 0–15 μg per 10 ml of the organic phase. The molar absorptivity is 12.1·10⁴ 1 mole^?1 cm^?1. Uranium can be determined in the presence of fluoride. sulfate and phosphate. Nitrate ion and elements (chromium, copper, iron) which affect the reduction of uranium(VI) or stability of uranium(IV) interfere.     

Spectrophotometric determination of tantalum with 4,5-dibromo-o-nitrophenylfluorone

Micro amounts of tantalum can be determined directly by spectrophotometry with 4,5-dibromo-o-nitrophenylfluorone, citric acid, hydrogen peroxide and Triton X-100 in 0.5–5 mol l^?1 sulphuric acid. The apparent molar absorptivity of tantalum at 530 nm is 1.84 × 10⁵ l mol^?1 cm^?1. Beer's law is obeyed for 0–10 μg of tantalum in 25 ml of solution at 530 nm and a large amount of niobium and most foreign ions can be tolerated. Results obtained by applying the proposed method to niobium oxide, ferroniobium, nickel-base alloy and a mineral are satisfactory. The synthesis of the complexing agent is described.     

Extractive spectrophotometric determination of molybdenum as a thiocyanate-2-acetylpyridinethiosemicarbazone complex

A new spectrophotometric method for the determination of molybdenum is based on the extraction of the orange red molybdenum thiocyanate-2-acetylpyridinethiosemicarbazone complex into chloroform from hydrochloric acid. The complex has an absorption maximum at 470 nm with a molar absorptivity of 1.7 × 10⁴ liters mol^?1 cm^?1. Beer's law is valid from 0.1 to 6.5 ppm of molybdenum. The equilibrium shift method indicated a 1:4:2 complex. The method has been used successfully for the determination of molybdenum in molybdenum steels.     

Spectrophotometric determination of acetone in acetic acid

A sensitive and selective spectrophotometric method for the determination of acetone in acetic acid has been worked out. It is based on the reaction of acetone with diazotized p-aminobenzoic acid in a strongly alkaline medium to form a purple color with maximum absorption at 540 nm. Beer's law holds up in the range 20–140 μg of acetone in a final volume of 20 ml, with a molar absorptivity of 8.1 × 10³ liters mol^?1 cm^?1, sensitivity index of 0.0072 μg cm^?2, relative error of ?1.9 to +0.6%, and relative standard deviation of 0.7–3.5, depending on the concentration level. Furthermore, the color reaction is fast, and the procedure is simple, and avoids the use of an extraction.     

The spectrophotometric determination of nitrite in water with 8-quinolinol

The method is based on the formation of a purple azoxine dye by coupling diazotized p-nitroaniline with 8-quinolinol. Beer's law is obeyed at 550 nm in the range 2–28 μg NO₂^- per 25 ml. The molar absorptivity and Sandell sensitivity are 3.88 × 10⁴ l mol^-1 cm^-1 and 0.0012 μg cm^-2, respectively.     

Rapid spectrophotometric determination of ruthenium(III) with prochlorperazine maleate

A rapid, simple spectrophotometric method for the determination of μg amounts of ruthenium, based on the formation of a pink complex between the metal and prochlorperazine maleate (PCPM) in sulphuric or hydrochloric acid solution, is described. The complex has an absorption maximum at 530 nm and its molar absorptivity is 6.733·10³ l mol^?1 cm^?1. The sensitivity is 0.0151 μg Ru cm^?2 for log I_o/I = 0.001. Beer's law is valid over the range 0.2–10 μg Ru ml^?1 ; the optimal range for spectrophotometric determination is 0.8–8.0 μg Ru ml^?1. Job's method of continuous variation, the mole ratio method and the slope ratio method indicate a 1:1 composition for the complex. The effects of acidity, time, temperature, order of addition of reagents, reagent concentration, and the interferences from various ions are reported.     

Rapid spectrophotometric determination of cerium(IV), arsenic(III), and nitrite with perphenazine

Perphenazine dihydrochloride, PPN, is proposed as a new reagent for the spectrophotometric determination of cerium(IV), arsenic(III), and nitrite. The reagent forms a red-colored species with cerium(IV) instantaneously in 3.5–5.5 M phosphoric acid medium. The red species exhibits maximum absorbance at 516 nm. A 15-fold molar excess of PPN is necessary for the full development of the color intensity. Beer's law is obeyed over the cerium concentration range 0.4–20 ppm and Sandell's sensitivity is found to be 0.016 μg/ cm². The effects of acidity, time, order of addition of reagents, temperature, reagent concentration, and diverse ions are reported. The proposed method offers the advantages of good sensitivity, simplicity, rapidity, selectivity, and a wider range of determination without the need for heating or extraction. Arsenic(III) and nitrite are also indirectly determined. The method is extended to the determination of cerium content in synthetic mixture corresponding to misch metal.     

An improved spectrophotometric determination of silicate in water based on molybdenum blue

Silicate in water is determined by a heteropoly blue method with ascorbic acid and antimony as reducing agents; antimony does not participate in the complex but enhances the absorbance. The method is comparatively fast and sensitive. Beer's law is obeyed for 0.02–1.2 μg ml^?1 silica. Interferences are discussed.     

Diazotized reagent for spectrophotometric determination of glyphosate pesticide in environmental and agricultural samples

A new sensitive spectrophotometric method for the determination of glyphosate herbicide in environmental and agricultural samples is developed. The reaction is based on diazotization followed by coupling of glyphosate with p-dimethyl amino benzaldehyde. The resulted complex absorption spectra was observed at λ_max = 420 nm. The effects of other metal ions and pesticides were also tested for selective determination of glyphosate. The analytical parameters were optimized and have been successfully applied for determination of glyphosate in various environmental samples such as soil, water and vegetables. This method has a lower limit detection of 6 μg of glyphosate. Beer's law is obeyed over the concentration range of 6.0 μg–24.0 μg glyphosate in 25 mL of the final solution at 420 nm. The standard deviation and relative standard deviation calculated are 0.0055 and 1.023, respectively. The molar absorptivity of the colored system is 1.91 × 10¹⁰ L mol^?1cm^?1 and Sandell's sensitivity is found 0.408 × 10^?5 μg cm^?2. The proposed method is simple, sensitive, highly reproducible and time saving as compare to those complicated time consuming methods.     

Tris(o-hydroxyphenyl)phosphine oxide as a colorimetric reagent for the determination of ferric iron

Tris(o-hydroxyphenyl)phosphine oxide is introduced as a new colorimetric reagent for the determination of ferric iron in solutions 0.3–2.5M nitric acid. The only other cation known to interfere in the determination is the ceric ion (Ce⁺⁴). The colour of the complex is stable and is found to obey Beer's law over a wide concentration range.     

Spectrophotometric determination of vanadium(V) and its application to vanadium steel containing chromium,molybdenum, manganese,and nickel

Promethazine hydrochloride forms a red colored species with vanadium(V) in 6.0–7.5 M phosphoric acid. A 16-fold molar excess of the reagent is necessary for full development of color intensity. Beer's law is valid over the concentration range of 0.1–7.0 ppm. The optimum concentration range as evaluated by Ringbom's method is 0.5–7.0 ppm. The sensitivity of the reaction is 0.005 μg cm^?2 and the molar absorptivity is 9.60 × 10³ liter mol^?1 cm^?1 at 517 nm. The effects of acidity, time, temperature, order of addition of reagents, reagent concentration, and the interferences from various ions were reported. Vanadium in vanadium steel containing chromium, molybdenum, manganese, and nickel was determined.     

Extraction—Spectrophotometric determination of nickel with 2-hydroxy-1-naphthaldoxime

A method for the solvent extraction—spectrophotometric determination of nickel with 2-hydroxyl-1-naphthaldoxime (HNA) has been studied. The method is based upon the formation of a nickel—HNA complex which is extracted into chloroform from an aqueous solution of pH 5.8. The nickel—HNA complex in chloroform exhibits an absorption maximum at 410 nm with molar absorptivity of 8.1 × 10³ liters mol^?1 cm^?1. Beer's law is applicable in the range from 5 to 50 μg of nickel. The mole ratio of the complex and effect of interfering ions are described.     

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 study of bismuth with N-(2-acetamido)iminodiacetic acid (ADA): Determination of bismuth in pharmaceutical formulations

A new method for the Spectrophotometric determination of bismuth using N-(2-acetamido)iminodiacetic acid as complexometric agent is proposed. The complex is formed in a wide pH range, 5.5–7.5, and has a maximum absorption at 265 nm. Beer's law is obeyed in the interval 3.8–17.9 μg of bismuth(III)/ml, with a minimum photometric error of 2.3. The molar absorptivity is 9.1 × 10³ liters/cm mol. The stoichiometry of the reaction takes place in the metal-to-ligand ratio 1:2. The interferences produced by the more common ions are studied. The method has been successfully applied to the determination of bismuth in pharmaceutical formulations.     

Spectrophotometric study of n,n'-bis(m-sulphobenzyl)dithio-oxamide as a reagent for nickel(II)

N,N'-Bis(m-sulphobenzyl) dithiooxamide forms a water-soluble intensely red chelate with nickel-(II) in buffered solutions at pH 10, A 1 Ni : 1R complex is obtained. The absorption maximum of the complex lies at 500 mμ, where the absorbance of (SB)₂DTO is negligible. The molar extinction coefficient is ca, 6962. Beer's law is obeyed over the range from 0.5 μg to 50 μg per ml.