Colored Azo Dye Research Articles

Estimating nitric oxide (NO) from MDSCs by Griess method.

The functional importance of nitric oxide (NO) in the fields of immunology concerning its antimicrobial, anti-tumoral, anti-inflammatory, and immunosuppressive effects have made it inevitable to study its secretion from various cells. Nitrogen oxide synthase (NOS) is the enzyme responsible for synthesizing NO and its three isoforms function in a cell-dependent manner. NO is oxidized rapidly to Reactive nitrogen oxide species (RNOS) through which the roles of NO are being carried out. One of the major immune cells secreting NO is myeloid-derived suppressor cells (MDSCs). The function of these MDSCs in the suppression of T-cell proliferation as well as T-cell differentiation is found to be dependent on NO secretion. Apart from T-cell suppressive activity, NO is also known to interfere with natural killer (NK) cell functions. A convenient method to estimate NO secretion is by using Griess reagent named after Johann Peter Griess. In this method, NO reacts with the reagents to form a colored azo dye detectable using a microplate reader at a wavelength of 548nm. In this chapter, we summarized the detailed method of estimating NO from MDSCs by the Griess method.

Improved Spectrophotometric Estimation of Nimodipine in the Pharmaceutical Formulation and Biological Fluids

Nimodipine (NDP) belongs to the class of pharmacological agents known as calcium channel blockers. It is used to treat symptoms resulting from a ruptured blood vessel in the brain (hemorrhage). NDP increases blood flow to injured brain tissues. For its clinical importance, a sensitive, accurate and simple spectrophotometric approach for the evaluation of NDP in bulk, tablet and biological fluids has been developed. The procedure involves the reaction of the reduced NDP with equimolar nitrous acid then followed by coupling with the available γ-resorsolic acid reagent in a basic solution to give a colored azo dye. The resulting azo dye is soluble in water and shows a maximum absorption peak at 436 nm. All the variables which affect the conditions such as the influence of acid, γ-resorsolic acid and alkali concentrations, reaction time and Beer׳s law limits were studied carefully and adjusted. The optimal conditions showed the color of azo-dye was stable for more than 1 h. The method was found linear in the range from 1.0 to 40 μg/mL with a good value of determination coefficient (R2= 0.9988). The molar absorptivity was calculated and set up to be 1.8495x104 L/mol.cm. The detection limits and quantitation limits were also estimated and found to be 0.0059 and 0.0195 μg/mL, correspondingly. The approach was established by estimating NDP in pharmaceutical tablets and biological fluids. The precision (RSD) was calculated to be better than 0.324%, whereas the values of recovery percent and relative errors were in the range of 97.95% to 99.08 % and -3.78% to 2.22%, respectively, without interfering from any common excipients present in the samples. The nature of the yellow dye has been studied between diazotized NDP and γ-resorsolic acid reagent and was equal to 1:1.

Spectrophotometric Assay of phenylphrine hydrochloride Viacuopling with Diazotised p-Nitroaniline, Application toPharmaceutical Preparation

Simple, sensitive and reproducible spectrophotometric method was developed in aqueous medium and applicated for the estimation of pheylephrine hydrochloride in nasal drop and tussilet syrup. The method is based on the formation of orange coloured azo dye from the coup I ing of pheylephrine hydrochloride (PPH) with diazotised p-nitroaniline in alkaline medium of sodium hydroxide and sodium carbonate. The intensity of absorbance for the resulting orange azao-dye was measured at 490 nm in sodium hydroxide and at 487 nm in sodium carbonate. Beer's law was obeyed in the concentration ranges of 10-200µg of PPH (r2=0.9988) in sodium hydroxide and of 10-lSOµg of PPH (r2=0.9981) in sodium carbonate in a final volume of 10 ml, with molar absorptivity of l.14xl04 1.mor1 .cm-1 in sodium hydroxide and l.98x 104 l.mor1 .cm-1 in sodium carbonate. The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation was+0. 8 to + 1.53% and relative error was - 1.6 to+ 1.7% depending on the concentration level of (PPH), while being simple, cheap and less time consuming. The azo-dye was stable for more than 2 hours in sodium carbonate and for 13 hours in sodium hydroxide .The proposed method was successfully applied for the dtermination of phenylephrine hydrochloride in pharmaceutical nasal drops and tussilet syrup formulations.

The Spectrophotometric Determination of Antiepileptic Drug in Standard and Pharmaceutical Formulations by Diazotization Coupling Reaction and Some Metals Complexes

A rapid, sensitive spectrophotometric method has been proposed for the determination of Gabapentin antiepileptic drug in pure and in pharmaceutical preparations was developed. The method is based on the coupling reaction between Gabapentin with8-hydroxy quinoline in to form an olive colored azo dye which gave maximum absorption at 365nm.The optimum reaction conditions like: pH, Temperature affected and time of reaction were evaluated. The ligand and its complexes were characterized by UV-visible spectroscopy, infrared FT-IR, (C.H.N.) analysis and Molar conductivity. The ratio of (metal: ligand) of all complexes was (1:2) by using molar ratio method and jop’s method. Beer’s law is obeyed for ligand and its complexes with (Cu2+, Ni2+,Cd2+, Co2+ and Zn2+) in concentration ranges ( 2 - 20, 1.5 - 25, 1 - 20, 2 - 25 and 2-30μg ml-) respectively . The molar absorptivity also calculated and it's found to be (1.396×104, 2.0208×104, 2.295×104, 1.684×104 and 1.862×104 L.mol-1.cm-1) for Cu2+, Ni2+,Cd2+, Co2+ and Zn2+complexes respectively. The detection of limit and quantification of limits are also calculated. The stability constant of complexes equal to(3.273×106, 1.695×102, 7.859×106, 1.851×105 and 1.588×102 L2.mol-2) for Cu2+, Ni2+,Cd2+, Co2+ and Zn2+ complexes respectively. The method is successfully used for the determination of Gabapentin in pharmaceutical formulations. Analytical parameters like accuracy and precision for the method have been established and evaluated statistically to assess the application of the proposed method. No interferes observed in the proposed method. The complexion with five ions (Cu2+, Ni2+, Cd2+, Co2+ and Zn2+) were studying. The aim of present work was devoted to investigate the reaction between Gabapentin and 8-hydroxy quinoline to form color Azo dye and use this product in the development of sensitive and simple spectrophotometric method for determination of Gabapentin in its pure and pharmaceutical preparations and spectrophotometric studies of a azo dye formed and it's metal complexes with Cu2+, Ni2+, Cd2+, Co2+ and Zn2+ ions.

Selective stability-indicating methods for the determination of clonidine hydrochloride and/or its related substance, 2,6-dichloroaniline

Three rapid, sensitive and selective analytical methods were developed for the determination of clonidine hydrochloride and its related substance: 2,6-dichloroaniline in a mixture of both. The first method depends on derivative-ratio spectrophotometry where the first derivative signals of the ratio spectra at 228.4 nm (Δλ = 2 nm) were selected to determine clonidine hydrochloride. The second method is based on measuring the first derivative response of 2,6-dichloroaniline at 300.8 nm with no interference from intact clonidine hydrochloride. In the third method, 2,6-dichloroaniline was determined via diazotization and coupling with N-(1-naphthyl) ethylenediamine to yield a colored azo dye which was measured at 498 nm. Various parameters affecting each method were studied and optimized. The proposed methods were validated according to USP guidelines concerning linearity, ranges, accuracy, precision, detection and quantification limits. The derivative-ratio spectrophotometric method was applied to the analysis of clonidine hydrochloride in tablets and the results were found in good agreement with those of the USP XXX HPLC procedure, while both the second and third methods permitted the selective analysis of 2,6-dichloroaniline in clonidine hydrochloride raw material.

Niobium Oxide Catalysts as Emerging Material for Textile Wastewater Reuse: Photocatalytic Decolorization of Azo Dyes

Niobium-based metal oxides are emerging semiconductor materials with barely explored properties for photocatalytic wastewater remediation. Brazil possesses the greatest reserves of niobium worldwide, being a natural resource that is barely exploited. Environmental applications of solar active niobium photocatalysts can provide opportunities in the developing areas of Northeast Brazil, which receives over 22 MJ m2 of natural sunlight irradiation annually. The application of photocatalytic treatment could incentivize water reuse practices in small and mid-sized textile businesses in the region. This work reports the facile synthesis of Nb2O5 catalysts and explores their performance for the treatment of colored azo dye effluents. The high photoactivity of this alternative photocatalyst makes it possible to quickly obtain complete decolorization, in less than 40 min of treatment. The optimal operational conditions are defined as 1.0 g L−1 Nb2O5 loading in slurry, 0.2 M of H2O2, pH 5.0 to treat up to 15 mg L−1 of methyl orange solution. To evaluate reutilization without photocatalytic activity loss, the Nb2O5 was recovered after the experience and reused, showing the same decolorization rate after several cycles. Therefore, Nb2O5 appears to be a promising photocatalytic material with potential applicability in wastewater treatment due to its innocuous character and high stability.

Spectrophotometric Determination of Oxymetazoline Hydrochloride in Pure and Pharmaceutical Preparations Using Diazo-coupling Reaction

A ccurate and simple spectrophotometric method has been suggested for the determination ofoxymetazoline hydrochloride (OMCl) in aqueous solution is developed. The present process included coupling of OMCl with diazotized sulphanilic acid reagent in the presence of sodium hydroxide. The orange colored azo dye formed very stable and soluble in water gives maximum absorption at 496 nm. The lineratey is obeyed over the range 20 – 400 mg / 25 ml (0.8 –16µg.ml-1) the molar absorptivity is equate to 2.30 ´ 104 l.mol-1cm-1. The proposed method has been used to the determination of OMCl in two formulations with satisfactories results.

Kinetic - Spectrophotometric Estimation of Tetracycline in Bulk and Pharmaceutical Forms

Simple and sensitive spectrophotometric method is described based on the coupling reaction of tetracycline hydrochloride(TC. HCl) with diazotized 4-aminopyridine in bulk and pharmaceutical forms. Colored azo dye formed during this reaction is measured at 433 nm as a function of time. Factors affecting the reaction yield were studied and the conditions were optimized. The kinetic study involves initial rate and fixed time (10 minutes) procedures for constructing the calibration graphs to determine the concentration of (TC. HCl). The graphs were linear for both methods in concentration range of 10.0 to 100.0 µg.mL-1. The recommended procedure was applied successfully in the determination of (TC. HCl) in itscommercial formulations.

High-Performance Monolithic Photovoltaic–Thermoelectric Hybrid Power Generator Using an Exothermic Reactive Interlayer

A high-performance monolithic photovoltaic–thermoelectric hybrid generator with a photothermal conversion layer is introduced. The layer, a thin acrylic film dyed with black colored AZO dye, effectively absorbs photons in the near-infrared region. The AZO dye supports an exothermic reaction through nonradiative relaxation. The hybrid generator was fabricated through monolithic integration. A thermoelectric (TE) module was fabricated directly on the back surface of the photovoltaic (PV) module without using the ceramic substrate typically employed in conventional TE modules, so that thermal resistance between the PV module and TE module could be minimized. The 51.35 cm2 fabricated hybrid generator showed a power conversion efficiency of about 22.5% with an open-circuit voltage of 0.94 V and a maximum power of 1.15 W under standard AM 1.5G illumination. The hybrid power generator with the photothermal conversion layer showed about 40% higher output power compared to the control PV only, about 16% higher tha...

Spectrophotometric properties of azo dye metal complex and its possible use as radiation dosimeter

The current work describes the physico-chemical studies of two dosimetry systems. Aqueous solution of 1, 5 diphenyl carbazone (DPC) incorporating with chromium (III) to form a colored azo dye metal complex in two methods liquid and gel. Under the effect of γ-irradiation, the colored complex undergoes visual color change from red to colorless. The prepared complex can be used as a dosimeter and applicable in dose range 0.2–6; 0.02–1 kGy for both dosimetry systems. Electrical conductivity was measured and reflecting its application as sensor. The dosimetric characteristics of this complex solution were investigated spectrophotometrically at גmax at 540 nm. Complex sensitivity for γ-radiation, pre and post-irradiation storage under different conditions were illustrated. Moreover, the applications of these results of metal uptake resembles to dosimeter.

Spectrophotometric Determination of Cefixime Following Simple Diazotization and Coupling with ?-Naphthol

Cefixime (CFX) was treated with sodium nitrite and hydrochloric acid for diazotization reaction followed by coupling with ?-Naphthol in alkaline medium to form, a yellow colored azo dye compound which exhibits maximum absorption (?max) at 412 nm where the concentration of (CFX) was determined spectrophotometrically. The optimum reaction conditions and other analytical parameters were evaluated. Beer’s law was obeyed in the concentration range of (1-20) ?g.mL-1 with a molar absorptivity of 34870.5 L.mol-1.cm-1. The limit of detection was found to be 0.1090 ?g.mL-1 and the Sandell's sensitivity value was 0.0130 ?g.cm-2. The proposed method could be successfully applied to the determination of (CFX) in pharmaceutical formulations.

Spectrophotometric Determination of Cefixime Following Simple Diazotization and Coupling with ?-Naphthol

Cefixime (CFX) was treated with sodium nitrite and hydrochloric acid for diazotization reaction followed by coupling with ?-Naphthol in alkaline medium to form, a yellow colored azo dye compound which exhibits maximum absorption (?max) at 412 nm where the concentration of (CFX) was determined spectrophotometrically. The optimum reaction conditions and other analytical parameters were evaluated. Beer’s law was obeyed in the concentration range of (1-20) ?g.mL-1 with a molar absorptivity of 34870.5 L.mol-1.cm-1. The limit of detection was found to be 0.1090 ?g.mL-1 and the Sandell's sensitivity value was 0.0130 ?g.cm-2. The proposed method could be successfully applied to the determination of (CFX) in pharmaceutical formulations.

A Highly Sensitive Kinetic-Spectrophotometric Method for the Assay of Carbamazepine in Pure and Commercial Tablet

The study aimed to recommend a new spectrophotometric-kinetic method for determination of carbamazepine (CABZ) in its pure form and pharmaceutical forms. The proposed procedure based on the coupling of CABZ with diazotized sulfanilic acid in basic medium to yield a colored azo dye. Factors affecting the reaction yield were studied and the conditions were optimized. The colored product was followed spectrophotometrically via monitoring its absorbance at 396 nm. Under the optimized conditions, two method (the initial rate and fixed time (10 minute)) were applied for constructing the calibration graphs. The graphs were linear in concentration ranges 2.0 to 18.0 µg.mL-1 for both methods. The proposed was applied successfully in the determination of CABZ in its commercial formulations. Keywords: Kinetic, Spectrophotometry, Carbamazepine, Pharmaceutical formulations

A Highly Sensitive Kinetic-Spectrophotometric Method for the Assay of Carbamazepine in Pure and Commercial Tablet

The study aimed to recommend a new spectrophotometric-kinetic method for determination of carbamazepine (CABZ) in its pure form and pharmaceutical forms. The proposed procedure based on the coupling of CABZ with diazotized sulfanilic acid in basic medium to yield a colored azo dye. Factors affecting the reaction yield were studied and the conditions were optimized. The colored product was followed spectrophotometrically via monitoring its absorbance at 396 nm. Under the optimized conditions, two method (the initial rate and fixed time (10 minute)) were applied for constructing the calibration graphs. The graphs were linear in concentration ranges 2.0 to 18.0 µg.mL-1 for both methods. The proposed was applied successfully in the determination of CABZ in its commercial formulations.
 Keywords: Kinetic, Spectrophotometry, Carbamazepine, Pharmaceutical formulations

Spectrophotometric Determination of Carbofuran with Diazotized Benzidine in Environmental Water Samples

A simple, rapid, accurate and sensitive spectrophotometric method has been developed for the determing carbamate pesticides in both pure and water samples. The method is appropriate for the determination of carbofuran in the presence of other ingredients that are usually available in dosage forms. The effect of organic solvents on the spectrophotometric properties of the azo dye and the structure of the resulting product have also been worked out and it is found to be 1:1 benzidine :carbofuran. The method can be successfully applied to determination of carbofuran in water samples. The method is based on diazotization of Benzidine (4, 4 – diamino biphenyl) with sodium nitrite and hydrochloric acid followed by coupling with carbofuran in alkaline medium to form a yellow colored azo dye having the absorption maximum at 429nm against reagent blank solution. Beer’s law is obeyed in the concentration range of (0-14) ?g of 10mL carbofuran. Molar absorptivity of 1×104 L.mol-1.cm-1 which depend on the concentration level of carbofuran.

Multivariate analysis of digital images of a paper sensor by partial least squares for determination of nitrite

Here, a disposable ultra-low cost and simple paper-based sensor (PBS) for on-site quantification of nitrite in environmental matrices is introduced. The PBS consists of a filter paper disc with 1.2cm in diameter that is impregnated with the Griess reagents including 3-nitroaniline, 1-naphthylamine and hydrochloric acid with the optimal concentrations obtained by response surface methodology. After introducing 20.0µL of a sample/standard solution to the sensor, nitrite reacts with the Griess reagents on the sensor and produces the red-pink colored azo dye after 30min. By use of a digital camera, the image of the PBS is captured and then analyzed by partial least squares for nitrite determination. The use of a blank and sample image reduces bias from variations in ambient light and makes it possible to acquire and process images on-site. In order to demonstrate the potential impact of this technology in the environment monitoring, the device was successfully applied to the analysis of a series of water samples, including tap, rain and wastewater. The results of the method were validated by standard method.

Spectrophotometric Determination of Carbofuran with Diazotized Benzidine in Environmental Water Samples

A simple, rapid, accurate and sensitive spectrophotometric method has been developed for the determing carbamate pesticides in both pure and water samples. The method is appropriate for the determination of carbofuran in the presence of other ingredients that are usually available in dosage forms. The effect of organic solvents on the spectrophotometric properties of the azo dye and the structure of the resulting product have also been worked out and it is found to be 1:1 benzidine :carbofuran. The method can be successfully applied to determination of carbofuran in water samples. The method is based on diazotization of Benzidine (4, 4 – diamino biphenyl) with sodium nitrite and hydrochloric acid followed by coupling with carbofuran in alkaline medium to form a yellow colored azo dye having the absorption maximum at 429nm against reagent blank solution. Beer’s law is obeyed in the concentration range of (0-14) ?g of 10mL carbofuran. Molar absorptivity of 1×104 L.mol-1.cm-1 which depend on the concentration level of carbofuran.

Spectrophotometric Determination of Sulfadiazine via Diazotization and Coupling Reaction - Application to Pharmaceutical Preparations

A simple, rapid, accurate and sensitive spectrophotometric method has been developed for the quantitative determination of sulfadiazine (SDz) in both pure and its dosage forms. The method is based on diazotization of primary amine group of sulfadiazine with sodium nitrite and hydrochloric acid followed by coupling with γ-resorsolic acid (2,6dihydroxybenzoic acid) in alkaline medium of sodium hydroxide to form a yellow coloured azo dye shows a maximum absorption at 458 nm against reagent blank solution. Beer's law is obeyed over the concentration range of 10-300 µg of SDz / 25 ml (0.4-12 ppm) with a determination coefficient (R 2 =0.9998 ) and molar absorptivity 4.38×10 4 l.mol -1 .cm -1 and a relative error in the range of 0.1- 0.64% and a relative standard deviation from ± 0.27 to ± 1.21 % depending on the concentration level of SDz. The method is suitable for the determination of sulfadiazine in the presence of other ingredients that are usually present in dosage forms. The effect of organic solvents on the spectrophotometric properties of the azo dye and the composition of the resulting product have also been worked out and it is found to be 1:2 γ-resorsolic acid: sulfadiazine. The method has been successfully applied to the determination of sulfadiazine in its pharmaceutical preparations ( tablet, and burn cream ).

Spectrophotometric Determination of Ascorbic acid in Aqueous Solutions and in Pharmaceuticals formulations

A new sensitive colorimetric method for determination of ascorbic acid tablet in aqueous solution. The method is based on the formation of colored azo dye by diazotization of 2, 4dichloroaniline followed by azo-coupling reaction between the resulting product and ascorbic acid. The optimum conditions that gave maximum absorption of azo dye at535nm, with best concentration of reactant and order of addition were studied to get the highest sensitivity (e=2315) L.mol -1 .cm -1 with a wide range of calibration curves (2-70) µg/ml good repeatability (RSD% 0.68 and 1.49), the recovery (99.56 - 100.30)%, Erel% (-0.20 and 0.44) were gave , Pharmaceutically prepared tablets were measured with the new technique using standard addition method given a very good recovery % (101.25 and 98.77) with a small Erel% (-1.25 and 1.23).

Spectrophotometric Determination of Teicoplanin via Coupling with Diazotized p-Nitroaniline

A new, simple and sensitive spectrophotometric method was described for the determination of teicoplanin as a pure material and in pharmaceutical formulation. The method is based on the coupling of teicoplanin with diazotized p-nitroaniline in alkaline medium. The dye shows an absorption maximum at 490 nm and obeys Beer's law over a range of 2 to 80 µg.ml.-1 of teicoplanin. The molar absorptivity of the coloured azo dye is 2.8 x 104l. mol-1cm-1. The relative standard deviation does not exceed 2.7 % (n=5). The azo dye formed is stable for 60 minutes. The method was applied successfully to the assay of teicoplanin in pharmaceutical preparation (injection).