Spectrophotometric determination of cerium(IV), arsenic(III), and nitrite with promazine hydrochloride

Promazine hydrochloride is proposed as a new reagent for the spectrophotometric determination of cerium(IV), arsenic(III), and nitrite. The reagent forms a red-colored radical with cerium(IV) instantaneously in 0.5?2 M sulfuric acid or 0.5?2.5 M phosphoric acid solution. The red radical exhibits maximum absorbance at 505 nm. An 11-fold molar excess of the reagent is necessary for the full development of the color intensity. Beer's law is valid over the concentration range 0.5–15 ppm in sulfuric acid and 0.5–21 ppm in phosphoric acid. The sensitivities of the reaction in sulfuric and phosphoric acid media are 0.022 and 0.019 μg/cm², respectively. 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 extraction. Arsenic(III) and nitrite are indirectly determined.     

Prochlorperazine bismethanesulfonate: Sensitive and selective reagent for the spectrophotometric determination of microgram amounts of osmium

Prochlorperazine bismethanesulfonate (PCPMS) is proposed as a new sensitive and selective reagent for the spectrophotometric determination of microgram amounts of osmium. PCPMS forms a red-colored species with osmium(VIII) or osmium(VI) instantaneously at room temperature in 5 M phosphoric acid medium. The red species exhibits maximum absorbance at 529 nm. Beer's law is valid over the concentration range 0.05–3.6 ppm for osmium(VIII) and 0.15–6.4 ppm for osmium(VI). Sandell's sensitivity of the reaction is 2.89 nm cm^?2 for osmium(VIII) and 4.24 ng cm^?2 for osmium(VI). The effects of time, temperature, acidity, order of addition of reagents, reagent concentration, and diverse ions are investigated. The application of the proposed method in the determination of osmium content in synthetic ores has been explored.     

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.     

The determination of thallium(III) with the 2,2'-bipyridyl-iron(II) chelate

A spectrophotometric determination of thallium (III), based on solvent extraction of an ion-association pair formed between the cationic 2,2'-bipyridyl-iron(II) chelate and the anionic thallium(III) bromide complex is described. The best extractant is 1,2-dichloroethane and extraction is possible over the pH range 2.5–6.7. The composition of the extracted species was confirmed, and conditions were established for the extraction over the concentration range 7.9·10^-6–3.5·10^-5M of thallium in aqueous solution.     

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.     

Determination of traces of hydrogensulfite by chemiluminescence with cerium(IV) sulfate as the reagent

Trace amounts of hydrogensulfite in aqueous solution (0.19–50 ng ml^?1 SO₂) are determined continuously with a chemiluminescence method based on a cerium(IV) sulfate reagent at pH 1.8. The intensity per unit SO₂ concentration is about 5 times that obtained with a permanganate reagent. The inhibitory effects of nitrite, transition metal ions and formaldehyde are also reduced.     

Solvent extraction and photometric determination of a microgram of cerium with N-p-tolyl-p-chlorobenzohydroxamic acid

A spectrophotometric method for determination of a microgram quantity of cerium with N-p-tolyl-p-chlorobenzohydroxamic acid is described. The orange-red-colored complex is extracted from chloroform at pH 9 which absorbs between 460 and 465 nm. Beer's law is obeyed at this wavelength. A clean-cut separation from many commonly occurring metal ions is easily accomplished. The system obeys Beer's law within the range of 0.5–28 ppm of cerium(IV). The molar absorptivity of cerium-N-p-tolyl-p-chlorobenzohydroxamic acid complex is 4.5 × 10³ liters mol^?1 cm^?1.     

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 microamounts of gold(III) with propericiazine

Propericiazine is proposed as a new reagent for the spectrophotometric determination of gold(III). The reagent forms an orange-red-colored species with gold(III) instantaneously in 4–8 M phosphoric acid. The orange-red species exhibits maximum absorbance at 511 nm. Beer's law is valid over the concentration range 0.1–7.0 μg/ml. The molar absorptivity is found to be 3.85 × 10⁴ liter mol⁻¹ cm⁻¹. The effects of acidity, time, order of addition of reagents, temperature, reagent concentration, and diverse ions are investigated.     

Rapid and selective determination of osmium(IV) by UV-visible spectrophotometry using o-methylphenyl thiourea as a chromogenic chelating ligand: sequential separation of osmium(IV), rhodium(III) and platinum(IV)

The objective of this research work was to develop a simple, highly sensitive and precise method for spectrophotometric determination of osmium(IV). O-Methylphenyl thiourea (OMPT) coordinates with osmium(IV) as a 1:1 (osmium(IV)–OMPT) complex in hydrochloric acid media (0.8 mol l^?1). The novelty of the investigated method is instant complex formation at room temperature with no need of heating or standing. The complex is stable for more than 8 days. The method is applicable over a wide linearity range (up to 110 µg ml^?1). A low reagent concentration is required (2 ml, 0.009 mol l^?1 in ethanol). The complex exhibits maximum absorption in the range of wavelength 510–522 nm and 514 nm was selected for further study. The molar absorptivity was 1.864 × 10³ l mol^?1 cm^?1, Sandell’s sensitivity was 0.102 µg of osmium(IV) cm^?2. Proposed method was successfully applied for separation and determination of osmium(IV) from binary and ternary synthetic mixtures containing associated metal ions. A scheme for mutual separation of osmium(IV), rhodium(III) and platinum(IV) is developed.     

Spectrophotometric determination of vanadium(IV) with nitrilotriacetic acid

A new and convenient spectrophotometric method for the estimation of vanadium(IV) with NTA is described. The minimum ratio of metal ion to ligand, working pH, wavelength for maximum absorbance of the complex ion, and the effect of various cations and anions are described. The complex ion obeys Beer's law in the concentration range 1–32 mmol/liter of the vanadium(IV) ion. It is observed that iron(II), cobalt(II), nickel(II), copper(II), and oxidizing anions such as chromate and nitrite interfere in this determination, whereas managanese(II), chromium(III), iron(III), and anions like nitrate, chloride, bromide, iodide, thiocyanate, sulfate, and sulfite do not have any effect. Excessive amounts of acetate, phosphate, oxalate, tartrate and thiosulfate must also be avoided in this determination. Anions and cations which interfere in the determination of vanadium(IV) by NTA should not be present in the system.     

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.     

Solvent extraction and spectrophotometric determination of titanium(IV) with 3-phenyl-3-methyl-2-mercaptopropenoic acid

The distribution equilibria of 3-phenyl-3-methyl-2-mercaptopropenoic acid (PhMMP) and the titanium(IV)-PhMMP complex have been studied. An extraction-photometric method for the determination of microamounts of titanium has been developed. We have investigated the influence of pH, the reagent, and the presence of electrolytes and masking agents in the aqueous phase on the equilibrium. From the slope analysis of the distribution curves the composition of the extracted species has been found to be Ti(OH)₂(HR)₂. The complex is extracted quantitatively. Beer's Law is followed over the range 0.09–3.74 μg ml^?1 of titanium(IV), the molar absorptivity is 1.65 × 10⁴ liters mol^?1 cm^?1, and the Sandell sensitivity is 2.8 ng cm^?2 at 439 nm. This method has been applied to the determination of titanium in a bauxite.     

The spectrophotometry and solvent-extraction behaviour of iron(III), vanadium(IV and V) and titanium(IV) chelates of 1-(o-carboxyphenyl)-3-hydroxy-3-methyltriazene

l-(o-Carboxyphenyl)-3-hydroxy-3-methyltriazene is proposed as an excellent reagent for the spectrophotometric determination of iron(III) and titanium(IV), and also for the separation of titanium from a large quantity of iron as well as other cations and anions. Iron(III) forms an anionic violet 1:2 complex at pH 4.0–9.4, and a cationic green 1:1 complex at pH 1.5–2.0, with absorption maxima at 570 nm and 660 nm, respectively. The violet complex is quantitatively extracted in chloroform containing n-octylamine at pH 3.0–9.0. The green and the violet iron(III) complexes obey Beer's law, the respective optimal ranges being 8.9–35.8 and 3.9–11.2 p.p.m. The yellow titanium chelate extracted into chloroform (absorption maximum at 410 nm) between pH 1.0 and 3.5, can be re-extracted into concentrated sulphuric acid a violet colour being produced with absorption maximum at 530 nm. Beer's law is obeyed in the ranges 0.8–5.7 p.p.m. for the titanium complex in chloroform and 3.4–19.2 p.p.m. when extracted in concentrated sulphuric acid. Interferences from diverse ions are not severe. Procedures for the separation and determination of titanium in the presence of a large quantity of iron are given. The isolation of the iron(III) and vanadium(IV and V) complexes, and their properties, are described.     

A rapid method for the spectrophotometric determination of palladium(II) and osmium(VIII)

Propionyl promazine phosphate is proposed as a new reagent for the rapid spectrophotometric determination of microgram amounts of Pd(II) and Os(VII). PPP instantaneously forms an orange-red 1:1 complex with Pd(II) in sodium acetate-hydrochloric acid buffer of pH 0.8 to 4.0 at room temperature. The reagent also forms an orange-red radical cation with Os(VIII) in 0.5 to 2.0 M hydrochloric acid. The Pd-PPP complex exhibits an absorption maximum at 490–500 nm with molar absorptivity of 7.1 × 10³ liter mol^?1 cm^?1. The Os-PPP radical cation has an absorption maximum at 505–515 nm with molar absorptivity of 2.21 × 10⁴ liters mol^?1 cm^?1. The Sandell sensitivity is 0.022 μg/cm² (Pd) and 0.008 μg/ cm² (Os). Beer's law is valid over the concentration range 0.2 to 21 ppm (Pd) and 0.2 to 4.2 ppm (Os). The proposed method offers the advantages of simplicity, rapidity, and without the need for heating or extraction. The reagent is used for the determination of Pd in the synthetic mixtures corresponding to Pd alloys used in jewelery and Os in osmiridium alloy.     

Spectrophotometric determination of copper(II) and its application to a plant sample containing zinc,iron, and manganese

Salicylaldehyde thiosemicarbazone instantaneously forms a green complex with copper(II) in the optimum pH range 5–7. A fivefold molar excess of the reagent is sufficient for the full development of the color. Beer's law is obeyed in the range 0.5–6.0 ppm of copper. The optimum concentration range as evaluated by Ringbom's method is 1.4–5.8 ppm. At 375 nm the sensitivity of the reaction and the molar absorptivity are 0.006 μg cm^?2 and 9.2 × 10³ liters mol^?1 cm^?1, respectively. The effects of pH, reagent concentration, time, order of addition of the solutions, and the interference of various ions were investigated. Copper in plant samples, containing zinc, iron, and manganese, was determined.     

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.     

Analytical separation of antimony(III) from bismuth(III), lead(II), gallium(III), thallium(III), tellurium(IV) and tin(IV) with cyanex 302

A method is proposed for the separation of antimony(III) (100–400 g) from bismuth(III), lead(II), gallium(III), thallium(III), tellurium(IV) and tin(IV) from an aqueous solution of pH 0.5–1.5 using 8×10^–3–1×10^–2 mol dm^–3 cyanex 302 dissolved in toluene as an extractant. The antimony is stripped from the cyanex phase with water and determined spectrophotometrically with iodide. Various experimental parameters are optimized and the probable 13 stoichiometry of the extracted species is evaluated. The method is applicable to the analysis of alloys and pharmaceutical samples. The separation and determination take only 20 min.     

Spectrophotometric determination of vanadium(V) with methoxypromazine maleate and its application to vanadium steels and minerals

The reagent in 8-fold excess forms a violet species with vanadium(V) instantaneously in 1–3 M phosphoric acid. The absorption maximum is at 565 nm; the molar absorptivity is 1.65 × 10⁴ l mol^?1 cm^?1. Beer's law is obeyed over the range 0.1–6.5 mg l^?1 vanadium (V); the optimum range is 0.3–6.0 mg l^?1; the Sandell sensitivity is 3.1 ng cm^?2. The method is simple and selective. The method is applicable for the determination of vanadium in vanadium steels and minerals.     

Determination of traces of ruthenium by addition of cerium(IV) and atomic absorption spectrometry

The sensitivity of the determination of ruthenium by flame atomic absorption spectrometry is increased 60 times by adding 1 × 10^?2 M cerium(IV). Calibration is linear over the range of 0.05–5 μg ml^?1 ruthenium. A method applicable to nitrosylruthenium complexes is described. The increased sensitivity results from formation of ruthenium tetroxide.