Direct and Derivative Spectrophotometric Determination of Zinc with 2,4-Dihydroxybenzaldehyde Isonicotinoyl Hydrazone in Potable Water and Pharmaceutical Samples

A simple and sensitive spectrophotometric method is developed for the determination of zinc in aqueous solutions. The metal ion forms a greenish-yellow colored complex with 2,4-dihydroxybenzaldehyde isonicotinoyl hydrazone (2,4-DHBINH) in the pH range of 4–10. The complex shows maximum absorbance at 390 nm and in the pH range of 6–8. Beer's law is obeyed in the range 0.10–1.50 μg/mL of Zn(II). The molar absorptivity and Sandell's sensitivity are 3.55 × 10⁴ mol⁻¹ cm⁻¹ and 0.0016 μg/cm², respectively. The composition of the complex is 1 : 1. The effect of interfering ions has been studied, and the method was applied to the determination of zinc(II) in potable water and pharmaceutical samples. A fast derivative spectrophotometry method is also proposed for the determination of zinc in the range 0.06–1.60 μg/mL, which is more sensitive than the zero order method. __________ Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 9, 2005, pp. 933–937. Original Russian Text Copyright ? 2005 by Sivaramaiah, Raveendra Reddy. The text was submitted by the authors in English.     

Flow Injection Chemiluminescence Determination of Retinol and α-Tocopherol in Blood Serum and Pharmaceuticals

A simple and sensitive flow-injection method is reported for the determination of retinol and α-tocopherol in human blood serum and pharmaceuticals. The method is based on the reduction of vanadium(V) by retinol and α-tocopherol and subsequent reaction of reduced vanadium with luminol to generate chemiluminescence signal. The optimized conditions allow a linear calibration range of 30–2850 µg L^?1 and 5–4300 µg L^?1 for retinol and α-tocopherol, with relative standard deviations of 1.2–4.6% and 1.5–5.6%, respectively. The detection limits for retinol and α-tocopherol, defined as three times the standard deviation of measured blanks were 23 µg L^?1 and 2.15 µg L^?1, respectively. The proposed method allowed up to 20 determinations h^?1. The tolerance amount of foreign ions/compounds on the determination of retinol and α-tocopherol was also examined. The method was applied to the determination of retinol and α-tocopherol in human blood serum and pharmaceutical samples using hexane extraction with recoveries in the range of 92 ± 2 to 96 ± 1%, and the results obtained were compared with HPLC reference method.     

Analytical applications of 4-(4′-methyl-2′-thiazolylazo)-2-methyl-resorcinol: Spectrophotometric determination of vanadium

4-(4′-Methyl-2′-thiazolylazo)-2-methyl-resorcinol reacts with vanadium (V) to produce a bluish-violet 1:1 complex (λ_max = 560 nm, ? = 2.50 × 10⁴M^?1 · cm^?1, 50% methanol-water medium), which allows the spectrophotometric determination of 0.1 to 1.4 ppm of vanadium. The method has been applied to the determination of vanadium in several low-alloy steels.     

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.     

Spectrophotometric Determination of Sparfloxacin in Pharmaceutical Preparations by Ternary Complex Formation with Pd(II) and Eosin

Abstract

A simple, sensitive, and direct spectrophotometric method has been developed for the assay of sparfloxacin in bulk and pharmaceutical preparations. The proposed method is based on the formation of ternary complex between an investigated drug, palladium(II) ion and eosin in the presence of methylcellulose as surfactant and acetate buffer of pH 4.2. Spectrophotometrically, under the optimum conditions, the ternary complex showed absorption maximum at 550 nm, with apparent molar absorptivity of 2.69×10⁴ l mol^?1 cm^?1, Sandell's sensitivity of 0.01458 µg ml^?1 and linearity in the concentration range 1.6–16 µg ml^?1. The composition of the ternary complex was studied by Job's method of continuous variation and the result indicated that the molar ratio of SPFX: Pd: eosin is 1∶1∶1. The optimum reaction conditions and other analytical parameters are evaluated. The proposed method was successfully applied for the determination of SPFX in its pharmaceutical product with mean percentage recoveries of 99.71%. The observed data has been subjected to statistical analysis, which revealed high accuracy and precision.     

Spectrophotometric determination of vanadium using variamine blue and its application to synthetic, environmental and biological samples

A simple, rapid and accurate spectrophotometric method is described for the determination of trace amounts of vanadium using variamine blue (VB) as a chromogenic reagent. The method is based on the oxidation of variamine blue to form a violetcolored species on reaction with vanadium(V), having an absorption maximum at 570 nm. Beer’s law is obeyed in the range of 0.1–2.0 μg ml^?1. The molar absorptivity and Sandell’s sensitivity were found to be 1.65 × 10⁴ l mol^?1 cm^?1 and 0.003 μg cm^?2, respectively. Optimum reaction conditions were evaluated in order to delimit the linear range. The effect of interfering ions on the determination is described. The proposed method has been successfully applied to the determination of vanadium in steel, pharmaceutical, environmental, and biological samples.     

Selective determination of selenium(IV) from environmental samples by UV-visible spectrophotometry using O-methoxyphenyl thiourea as a chelating ligand

A selective extraction–spectrophotometric method has been developed for determination of selenium(IV) using O-methoxyphenyl thiourea (OMePT) as a chelating agent. The basis of the proposed method is the spectrophotometric determination of selenium(IV)–OMePT complex obtained after extraction of selenium(IV) from 3.5 M hydrochloric acid media using OMePT in chloroform solvent. The complex shows maximum absorbance at 350 nm against the reagent blank. The Beer’s law was obeyed over the concentration range 5–60 µg mL^?1 of selenium(IV). The optimum concentration range was 20–50 µg mL^?1 as evaluated from Ringbom’s plot. The molar absorptivity and Sandell’s sensitivity of the selenium(IV)–OMePT complex in chloroform were 3.312 × 10² L mol^?1cm^?1 and 0.2384 µg cm^?2, respectively. The composition of selenium(IV)–OMePT complex was 1:2 established from slope ratio method, mole ratio method and Job’s continuous variation method. The complex was stable for more than 72 h. The interfering effect of various foreign ions was studied and suitable masking agents were used wherever necessary to enhance the selectivity of the developed method. The proposed method was successfully applied for the determination of selenium(IV) from real samples, viz. pharmaceutical formulations, shampoo, vegetable sample, synthetic mixtures and environmental samples. Repetition of the method was checked by finding the relative standard deviation (RSD) for 10 determinations which was 0.35%.     

Mixed Ligand Complexes of Vanadium(V): Extraction With Some New Hydroxamic Acids and Application in Steel.,Rock and Environmental Anaysis

Abstract

Five new substitued hydroxamic acids are used for extraction and spectrophotometric determination of vanadium(V) in trace amounts. the binary complex of vanadium (V) with H-p-ciloropheny 1-3,4,5-trimethoxycinnamohdroxamic acid (PTCHA) and the mixed ligand complex of vanadium (V) with N-p-cinlorpheny-p-chlorophenoxyisobutyrohydroxamic acid (PP3HA) and thiocyanete were studied. The molar absorbtivities of the bluish violet vanadium(V) hydroxamate and mixed ligand complexes are 6.9 × 10³ and 1.1 × 10⁴ cm³ mol^?3 cm^?1, respectively. The vanadium is also determined with AAs and the method is applied for its determination in steel. alloy, rock and environmental samples.     

Spectrophotometric Determination of Vanadium in Complex Materials Using N-m-TMBHA and Thiocyanate

Abstract

Vanadium(V) reacts with N-m-Tolyl-p-methoxy benzohydroxamic acid to form 1:2 (metal to ligand) complex containing a basic V=O group and an acidic V-OH group, which forms addition compounds with thiocyanate to give a hyper and bathochromic effect in chloroform. On the basis of this bathochromic effect of thiocyanate a rapid, selective and sensitive method for the spectrophotometric determination of vanadium(V) has been developed. The blue coloured complex of vanadium(V) is extractable in chloroform having absorption maxima at 580nm and max 7100 ±50 1. mole^?1 cm^?1. The method is free from interferences of Mo(VI), W(VI), Zr(IV) and has been successfully applied for the analysis of steels and other complex materials.     

A New Spectrophotometric Method for the Determination of Arsenic in Environmental and Biological Samples

Abstract

A simple and selective spectrophotometric method has been developed for the determination of trace amounts of arsenic using azure B as a chromogenic reagent. The proposed method is based on the reaction of arsenic(III) with potassium iodate in acid medium to liberate iodine. The liberated iodine bleaches the violet color of azure B and is measured at 644 nm. This decrease in absorbance is directly proportional to the As(III) concentration, and Beer's law is obeyed in the range 0.2–10 µg ml^?1 of As(III). The molar absorptivity, Sandell's sensitivity, detection limit, and quantitation limit of the method were found to be 1.12×10⁴ l mol^?1cm^?1, 6.71×10^?3 µg cm^?2, 0.02 µg ml^?1 and 0.08 µg ml^?1, respectively. The optimum reaction conditions and other analytical parameters were evaluated. The proposed method has been successfully applied for the determination of arsenic in various environmental and biological samples.     

Analytical applications of picolinealdehyde salicyloylhydrazone: II. Extraction and spectrophotometric determination of vanadium(V)

Picolinealdehyde salicyloylhydrazone reacts with vanadium(V) to produce a yellow 1:1 complex (λ_max = 400 nm, ? = 2.17 × 10⁴ liters · mol^?1 cm^?1) in aqueous ethanolic solution. The yellow complex can be extracted into chlorobenzene (λ_max = 425 nm, ? = 2.16 × 10⁴ liters · mol^?1 cm^?1) and used for the spectrophotometric determination of trace amounts of vanadium. Interferences have been investigated. The method has been applied to the determination of vanadium in steel and in lead concentrates.     

Selective solid phase extraction and preconcentration of ultra-trace inorganic mercury in water samples using 2,6-dimethyl-morpholine dithiocarbamate

A sensitive and selective solid-phase spectrophotometric method for the determination of trace amounts of Hg(II) cation in water is described. A complex was created with Hg(II) using 2,6-dimethyl-morpholine dithiocarbamate (DMMDTC) to form Hg(II)–(DMMDTC) and this complex was adsorbed onto microcrystalline naphthalene (MN) and then eluted with 5% acetic acid (in ethanol) solution. A preconcentration factor of 187 and a recovery of 95% were observed at pH of 5.0 and for 10 min. of extraction. The separated Hg(II) ions were quantified by using ultraviolet-visible spectrophotometer at 490.0 nm by creating a colored complex with dithizone in Triton X-100 surfactant media. Molar absorptivity and sandell’s sensitivity for the Hg(II)-dithizone were determined as 4.96 × 10⁵ Lmol^?1cm^?1 and 0.4032 µg cm^?2, respectively. The detection limit (LOD) was 1.7 μg L^?1 under the optimized conditions of the analytical method.     

Novel Reaction for Rapid,Simple, and Sensitive Determination of Molybdenum in Various Samples

Abstract

A new sensitive, selective, rapid, and reproducible method is presented for the analysis of trace amounts of molybdenum (VI) (Mo(VI)). The method is based on the reaction of molybdenum (VI) with a new analytical reagent, 6‐(5‐Chloro‐2‐hydroxy‐4‐sulfophenylazo)‐5‐hydroxy‐1‐naphthalenesulfonic acid, disodium salt. Under optimum reaction conditions, molybdenum (VI) forms a red complex with a maximum absorption peak at 589 nm. The color reaction is rapidly completed at room temperature. The apparent molar absorption coefficient and Sandell sensitivity were 1.13×10⁴ L · mol^?1 · cm^?1 and 0.0084 µg · cm^?2, respectively. Beer's law was obeyed up to 8.5 µg · mL^?1. Methods for the determination of Mo(VI) by first‐derivative spectrophtometry have also been proposed at 547 and 625 nm. The proposed methods offer the advantages of sensitivity, rapidity, selectivity, and simplicity without any prior separation or extraction. The methods have been applied to the determination of Mo(VI) in various environmental samples and some alloys; satisfactory results have been obtained.     

Determination of Ketotifen Fumarate in Raw Material and Pharmaceutical Products Using Ion‐pair Formation

Abstract

A simple and sensitive extractive spectrophotometric method has been described for the determination of Ketotifen. The developed method is based on the formation of a colored ion‐pair complex (1∶1 drug/dye) of Ketotifen and bromocresol green in buffer pH 3 and extraction in chloroform. The extracted complex shows absorbance maxima at 423 nm. Beer's law is obeyed in the concentration range of 5.15–61.91 µg/ml. The proposed method has been applied successfully for the determination of drug in commercial tablets and syrup dosage form. No significant interference was observed from the excipients commonly used as pharmaceutical aids with the assay procedure.     

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.     

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.     

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.     

A Novel Method for the Determination of Streptomycin Using Sodium Nitroprusside as a Chromogenic Reagent by Spectrophotometry

Abstract

A rapid and simple spectrophotometric method for the determination of streptomycin has been developed and validated. The method was based on the reaction of streptomycin with sodium nitroprusside in the alkaline medium forming a red product measured at the maximum absorption of 495 nm. The stoichiometric ratio of the product is 1:1. Beer's law is obeyed in a range of 1.87 µg mL^?1 ～ 279.8 µg mL^?1 of streptomycin and ?₄₉₅ is 6.0 × 10³ L·mol^?1 cm^?1.Under the optimum condition, the equation of linear regression is A = 0.00742 + 0.05683 C (× 10⁵ mol·L^?1), with a linear correlation coefficient of 0.9990. The detection limit (3σ/k) is 0.96 µg mL^?1, the relative standard deviation (RSD) is 2.40%, and the average recovery rate is 98.3%–102.7%. Every parameter has been optimized, and the reaction mechanism has been studied. The proposed method has been successfully applied to the determination of streptomycin for injections and tablets of pharmaceutical preparation. Analytical results obtained by this new method were very gratifying.     

Spectrophotometric determination of vanadium (V) with 2-naphthohydroxamic acid

2-Naphthohydroxamic acid in methanol gives an intense and stable red-orange color with vanadium (V), sensitive to 0.009 μg V/cm², for log I₀/I = 0.001 abs. unit at wavelength 450 mμ. The value for σ is ±0.006 a.u., equivalent to ±0.08 p.p.m. V. The colored complex obeys Beer's law over the range 1–10 p.p.m. vanadium. The absorbance (in 1-cm cell) at 10 p.p.m. was so great that no data were obtained at higher concentrations. Under the conditions of the reaction, the combining ratio of vanadium and 2-naphthohydroxamic acid appears to be 1 to 2. Optimum conditions for the use of 2-naphthohydroxamic acid as a spectrophotometric reagent for vanadium-(V) were established; the procedure was applied to the determination of vanadium in steels and non-ferrous alloys with good precision and accuracy.     

Trace Determination of Copper in Foodstuffs and Biological Samples

Abstract

A new heterocyclic bis-azo dye, 2,6-bis(4-sulfo-1-hydroxy-2-naphthylazo)pyridine, sodium salt (PBS), has been prepared and developed as a sensitive and highly selective chromogenic reagent for spectrophotometric determination of copper. The reagent is found to give a 1:2 (M/L) complex at pH 6.0. Beer's law is followed up to 1.8 ppm with an optimal concentration range between 0.2 and 1.4 ppm. Sandell's sensitivity of the color reaction was calculated to be 0.0013 µg cm^?2 with molar absorptivity of 4.9 × 10⁴ l·mol^?1 cm^?1 at 572 nm. The interfering effects of various cations and anions were also studied. The proposed method was successfully applied to the determination of copper(II) in milk, tea samples, cereals, and legume grains consumed by the Indian vegetarians and in some biological samples. Comparison of the results with those obtained using an atomic absorption spectrophotometer tested the validity of the method.