Determination of manganese(VII) as 3,3′-Dianisole-4,4′-bis(3,5-diphenyltetrazolium chloride) complex and its application

A simple, rapid, selective and sensitive spectrophotometric method is described for the determination of trace amounts of manganese using Blue tetrazolium chloride as a chromogenic reagent. The method is based on the formation of ion-associate complex between manganese(VII) and the cation of ditetrazolium salt, having an absorption maximum at 255 nm. Beer’s law is obeyed in the range of 0.1–1.6 μg mL^?1. The molar absorptivity and Sandell’s sensitivity were found to be 4.97 × 10⁴ L mol^?1 cm^?1 and 1.11 × 10^?3 μg cm^?2, respectively. Limit of deterction is 6.86 ng mL^?1 Mn(VII) and limit of quantitation is 22.8 ng mL^?1 Mn(VII). Optimum reaction conditions were evaluated. The effect of interfering ions on the determination is described. The extraction, distribution and association constants, and the recovery factor have been calculated.     

A highly sensitive spectrophotometric determination of gallium with chromal blue G in the presence of cetyltrimethylammonium chloride

A new spectrophotometric method for the determination of gallium with chromal blue G in the presence of cetyltrimethylammonium chloride is described. The sensitivity of color reaction between gallium and chromal blue G is greatly increased by the sensitizing action of cetyltrimethylammonium chloride. The gallium complex has maximal absorbance at 662 nm and pH 6.2–6.8. Beer's law is obeyed over the range 0.04–0.6 ppm of gallium. The molar absorptivity of the complex is 1.44 × 10⁵ liters mol^?1 cm^?1 at 662 nm, and the spectrophotometric sensitivity is 4.8 × 10^?4 μg Ga cm^?2. The mole ratio of gallium and chromal blue G in the complex is estimated to be 1:4. The formation constant and effect of interfering ions are described.     

Spectrophotometric determination of vanadium as vanadium(IV) pyridine thiocyanate

A spectrophotometric determination of vanadium as vanadium(IV) pyridine thiocyanate is described. The blue complex is formed in acidic aqueous solution and extracted into pyridine-chloroform. Absorbance is measured at 7.40 mμ. The range of best accuracy for 1-cm cells is from about 80 to 240 μg of vanadium per ml, and sensitivity is 0.4 μg of vanadium per cm² at 7.40 mμ. The vanadium may be present initially as vanadium(IV) or vanadium(V), which is reduced to vanadium(IV) by the large excess of thiocyanate ion added. Several elements interfere in the determination ; a separation procedure involving mercury cathode electrolysis is suggested.     

Extraction of gold(III) from low-grade ores with amidines followed by its spectrophotometric determination with methylene blue

A procedure is described in which gold(III) is quantitatively extracted with an amidine into chloroform over the acidity range pH 3.0–11.0 M HCl, followed by its selective spectrophotometric determination by interaction of the extract with methylene blue in the pH range 3.0–9.0. The molar absorptivity of the coloured complex formed by extraction with ten different amidines and methylene blue reaction lie in the range 1.1 × 10⁴?6.5 × 10⁴ 1 mol^?1 cm^?1 at λ_max (650 nm) in chloroform. The simplest compound, N, N′-diphenylbenzamidine, was chosen for detailed study. The limit of detection is 5 μg Au l^?1. The method is free from interferences from the metals that are generally associated with gold. The method is simple, reproducible and applicable to the accurate recovery of gold from low-grade ores containing the metal at levels of > 1.5 μg g^?1.     

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.     

Colorimetric Determination of Seleniumin Various Environmental Samples

A new reagent system using rhodamine‐B dye for the determination of selenium is described. The method is based on the reaction of selenium with acidified potassium iodide to liberate iodine. The liberated iodine bleaches the pink colour rhodamine‐B, which is measured at 555 nm. Beer's law is obeyed over the concentration range of 1–10 μg of selenium final solution volume of 25 mL (0.04–0.4 ppm) and the apparent molar absorptivity and Sandell's sensitivity was found to be 1.96× 10⁵ l mol^?1 cm^?1 and 0.0004 μg cm^?2, respectively. The method is simple, sensitive, and selective and is satisfactorily applied to micro‐level determination of selenium in various environmental and cosmetic samples.     

Extraction Spectrophotometric Determination of Vanadium in Industrial Waste Water

A new and simple extraction spectrophotometric method for the determination of vanadium(V) with KIO₄, N‐phenylbenzohydroxamic acid (PBHA) and crystal violet (CV), in industrial waste water samples is described. It is based on the extraction of mixed‐ligand complex V(V)‐IO₄^? ‐PBHA‐CV⁺ into chloroform solution over 2‐7 MHC1. The molar absorptivity of the complex is (7.20) × 10³1 mol^?1 cm^?1 at λ_max 535 nm. The detection limit of the method is 44 μg 1^?1 V. The linearity of the calibration curve is followed up to 6 μgmL^?1 in the organic solution with slope, intercept and correlation coefficient of 1.34 × 10^?1, 6.7 × 10^?3 and +0.99, respectively. This method enhances the sensitivity of the conventional PBHA method for the determination of vanadium, and is free from interferences of other metal ions commonly associated with vanadium. The method has been successfully tested for the determination of V in the industrial waste water samples.     

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.     

Extract-Photometric Determination of Vanadium with Isophthaldihydroxamic Acid

Abstract

The spectrophotometric study of violet complex isophthaldihydroxamic acid-vanadium extracted into solution of trioctylmethylammonium chloride in ethylacetate was made (λ_max = 380 nm, ? = 7500 l.mol^?1.cm^?1; λ_max = 510 nm, ? = 5510 l.mol^?1 .cm^?1; stoichiometries, 1:1 and 1:2, V:reagent). A new method for the extract-spectrophotometric determination of V(V) in the range 14–80 μg of vanadium is proposed.     

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.     

N-p-tolyl-2-furohydroxamic Acid as the Extracting and Spectrophotometric Reagent for Vanadium(V)

Abstract

A simple and rapid spectrophotometric determination of vanadium(V) is described. The vanadium-N-p-tolyl-2-furohydroxamic acid complex is extracted into chloroform form 6–8 molar hydrochloric acid solution. Maximum absorbance occurs at 540 nm and Beer's Law is obeyed over the range of 0–15 μg of vanadium in the organic phase. The molar absorptivity is 3.0 × 10³ mole^?1 cm^?1 at 540 nm.

Vanadium could be determined in high purity niobium and tantalum metals, cast iron, steel, non ferrous alloys and silicates. Vanadium could be determined in the presence of several commonly occurring cations.     

Indirect spectrophotometric determination of chromium(VI)

A new simple and sensitive spectrophotometric method for the determination of chromium(VI) is established. It relies upon the oxidation of iron(II) with the titled ion, in acidic medium, to form iron(III) which is complexed with tiron to form a stable blue color with maximum absorption at 650 nm. Adherence to Beer's law is observed in the range 10–100 μg of chromium(VI) per 25 ml, with a molar absorptivity of 5.6 × 10³ liters mol^?1 cm^?1, sensitivity index of 0.0093 μg cm^?1, relative error of ?5.0 to +0.3%, and relative standard deviation of 0.3–4.0%, depending on the concentration level. Furthermore, the reaction needs neither temperature control nor an extraction step.     

Quantitative Analysis of Nicorandil in Commercial Tablets by Spectrophotometry

The main aim of this work is to develop and validate a spectrophotometric method for the determination of nicorandil in commercial tablets. The method is based on the reduction of the nitroxy ethyl group of nicorandil into carbonyl compound and nitrite ion by NH₄Cl and Zn dust. The nitrite ion thus formed reacts with potassium iodide and starch in dilute HCl medium to form a blue product, which absorbs maximally at 550 nm. Beer's law is obeyed in the concentration range 0.4‐4.0 μg mL^?1 with molar absorptivity of 7.92 × 10⁴L mol^?1 cm^?1. The detection limit is 0.017 μg mL^?1. The reaction conditions are optimized and validated as per the International Conference on Harmonisation guidelines (USA). The proposed method has been applied successfully for the determination of nicorandil in commercial tablets. The results of analyses are compared statistically with those of the author's spectrophotometric method, which confirmed that there is no significant difference between the methods compared.     

Extractive Spectrqphotometric Determination of Vanadium Liith o-Aminobenzo-Hydroxamic Acid

Abstract

A new spectrophotometric method for vanadium determination is proposed. The method is based on the extraction in Adogen-toluene solution of the complex formed between V(V) and o-Aminobenzohydraxámic acid

The method allows determination of 50 to 110 μg of V(V). The error and the apparent molar absorptivity are 1.2% and 5.2 ± 10³ l.mol^?1. cm^?1 respectively. The interferences caused by foreign ions have been established. The method is applied with success to determination of vanadium in petroleum crudes.     

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.     

Selective Kinetic Spectrophotometric Determination of Nitrite in Food and Water

Abstract

A highly selective and sensitive method for the kinetic spectrophothometric determination of sub-microgram amounts of nitrite has been development based on its reaction with Nile blue 2B in acidic medium. The reaction is monitored spectrophotometrically at 595 nm at a fixed time of 4.5 min. The change in absorbance at 595 nm is related to the concentration of nitrite in the range 0.005 - 1.100 μg.ml^?1 The detection limit is 0.001 μg.ml^?1. The relation standard deviation is 1% for 0.020 μg.ml^?1 of nitrite for ten replicate measurements. Most common anions and cations do not interfere. The procedure was applied to the determination of trace amounts of nitrite in sausage and water.     

A Sensitive Spectrophotometric Determination of Nitrite in Water and Soil

A highly sensitive spectrophotometric method for the determination of nitrite in water and soil has been developed. The reaction of nitrite with acidified potassium iodide to liberate iodine which oxidizes leuco‐crystal violet (LCV) to form crystal violet having absorption maxima at 590 nm forms the bases of this method. In aqueous medium the system obeys Beer's law in the range of 0.1 to 1.0 μg per 25 mL (0.004–0.04 ppm), while in an extractive system the range is 0.025–0.25 μg in 100 mL (0.00025–0.0025 ppm). The molar absorptivity and Sandell's sensitivity were found to be 1.54 × 10⁶ 1 mol^?1 cm^?1 and 44 pg cm^?2, respectively.     

A Sensitive Colorimetric Method for the Determination of Arsenic in Environmental and Biological Samples

Results of a thorough study and application of leucocrystal violet for the determination of arsenic in parts per million (ppm) levels in environmental and biological samples is described here. The proposed method is based on the reaction of arsenic with potassium iodate to liberate iodine. The liberated iodine selectively oxidises leucocrystal violet to form crystal violet dye in the presence of sodium hydroxide. The dye formed shows maximum absorbance at 592 nm. The detection limit of arsenic is 0.002 μgmL^?1 and the method obeys Beer's law over the concentration range of 0.1 μg - 1.0 μg of per 25 mL of final solution (0.004–0.04 ppm). The molar absorptivity was found to be 1.49 × 10⁶ L mol^?1 cm^?1. The proposed method was successfully applied for the determination of arsenic in various environmental and biological samples. The results are in good agreement with the standard reported method.     

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.     

Extractive Determination of Vanadium in Fungi Samples

A new reagent system has been reported for the extractive separation and simultaneous spectrophotometric de termination of vanadium (V). The method is based on the formation of a water in soluble blue‐violet V(V) complex with N‐hydroxy‐N‐m‐tolyl‐N′‐phenylbenzamidine (HTPBA), and neutral surfactant Triton X‐100 into chloroform over an acidity range of 1.0–10.0 M acetic acid. The complex shows a broad absorption maximum at 570 nm, when measured against a chloroform blank. The λ_max (570 nm) of the complex and that of re agent (313 nm) are well separated, hence the excess of the reagent does not interfere in the spectrophotometric de termination of the metal. The molar absorptivity (?) of the complex is (4.74) × 10³ 1 mol^?1 cm^?1. The linearity of the calibration curve is followed between 0.5–12.0 μg mL^?1 with slope, intercept and correlation coefficient of 9.16× 10^?2, 4.5 × 10^?3 and 0.999, respectively. The detection limit of the method is 45 μgl^?1. The proposed re agent system provides significantly higher tolerance limit for iron (500 μg mL^?1) and also various metalions commonly associated with vanadium did not interfere. The method was applied for the deter mi nation of vanadium content of three samples i.e. Spirogyra, Puccinia and Riccia.