Chromotrope 2B Research Articles

Photocatalytic degradation of two selected dye derivatives, chromotrope 2B and amido black 10B, in aqueous suspensions of titanium dioxide

The photocatalytic degradation of two selected dye derivatives, chromotrope 2B ( 1) and amido black 10B ( 2), has been investigated in aqueous suspensions of titanium dioxide under a variety of conditions which is essential from an application point of view. The degradation was monitored by measuring the change in substrate concentration as a function of irradiation time employing UV spectroscopic analysis. In these studies, a number of byproducts are formed during the photooxidation process which can potentially be harmful to the environment, therefore, we have studied the mineralization of the pollutants by measuring the total organic carbon (TOC) as a function of irradiation time. The degradation of dyes were studied using different parameters such as types of TiO 2, reaction pH, catalyst concentration, substrate concentration and in the presence of different electron acceptors such as hydrogen peroxide (H 2O 2), potassium bromate (KBrO 3) and ammonium persulphate (NH 4) 2S 2O 8 besides molecular oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The photocatalyst Degussa P25 was found to be more efficient as compared with other photocatalysts. The dye derivative ( 1) was found to degrade faster as compared to the dye derivative ( 2).

Sorption–Optical Determination of Nitrite Ions in Sea Water with Chromotrope 2B

The Chromotrope 2B reagent was used as an analytical reagent for the direct determination of nitrite ions by sorption chromaticity measurements, diffuse reflectance spectrometry, and solid-phase spectrophotometry. The silochrom C-120 silica gel and the AV-17 anion exchanger were used as supports. Optimum conditions were found for the formation and sorption of Chromotrope 2B. The dependence of the chromaticity characteristics (chromaticity coordinates, lightness, color saturation, yellowness, and whiteness) on the concentration of nitrite ions was examined. The advantages of the use of chromaticity characteristics over the diffuse reflection coefficient were demonstrated. A procedure was developed for the test and sorption–optical determination of nitrite ions in sea water.

Novel, Sensitive Voltammetric Methods for Titanium Determination Using Chromotropic Acid and Azo‐Compounds as Complexing Agents

AbstractVoltammetric behavior of titanium(IV) complexes with chromotropic acid, its azo‐derivatives: 2‐(4‐sulfophenylazo)‐1,8‐dihydroxy‐3,6‐naphthalenedisulfonic acid (SPANDS), chromotrope 2B, sulfonazo III and other azo‐compounds: calmagite, tropeoline O and kalces was investigated at a hanging mercury drop electrode. These complexes strongly adsorb onto the electrode, thus can be determined by an adsorptive stripping voltammetry (optimal pH about 6). At pH about 3 reduction current enhancement for Ti‐kalces complex was observed in the presence of chlorate ions. It is a rare example of a catalytic process with azo‐compound as a complexing agent. Signal for Fe‐calmagite complex reduction was also observed. Influence of foreign ions and the optimal conditions for titanium determination are described in detail. Additionally, a connection between obtained results and a structure of titanium complexes is discussed.

Spectrophotometric determination of meclozine HCl and papaverine HCl in their pharmaceutical formulations

A simple, accurate and highly sensitive spectrophotometric method is proposed for the rapid determination of meclozine and papaverine hydrochlorides using chromotrope 2B (C2B) and chromotrope 2R (C2R). The method consists of extracting the formed ion-associates into chloroform in the case of meclozine HCl and into methylene chloride in case of papaverine HCl. The ion-associates exhibit absorption maxima at 536 and 524 nm for C2B and C2R with meclozine HCl and at 540 and 528 nm with papaverine HCl, respectively. Meclozine can be determined up to 4.0 and 2.6 mg ml −1, using C2B and C2R, respectively, while papaverine can be determined up to 1.68 and 1.37 mg ml −1, respectively. The effect of acidity, reagent concentration, time, solvent and stoichiometric ratio of the ion-associates were studied. The molar absorptivity and Sandell sensitivity of the reaction products were calculated. The method was applied to the determination of the drugs in their pure state or pharmaceutical preparations with mean recovery values of 99.63–100.80 and 99.75–100.08% and coefficient of variation 0.945–2.210 and 1.020–1.268 for meclozine HCl and papaverine HCl, respectively.

EXTRACTION-COLORIMETRIC METHOD FOR THE DETERMINATION OF ERYTHROMYCIN AND ITS ESTERS IN DOSAGE FORMS USING CHROMOTROPIC ACID AZO DYES

Accurate, rapid and sensitive extraction-colorimetric method for the determination of erythromycin and its esters, depending on the formation of an ion-pairs with chromotropic acid (I), chromotrope 2B (II), chromotrope 2R (III), arsenazo I (IV), arsenazo III (V), benzocaprol red (VI) and acid ethyl blue (VII) is described. The calibration curves resulting from the measurements of absorbance-concentration relations (at the optimum reaction conditions) of the extracted ion-pairs are linear over the concentration range 0.4–56 μg ml−1 with a relative standard deviation (RSD) of 1.3% for 25 μg ml−1 erythromycin. The detection limit, quantification limit, the molar absorptivity and Sandell sensitivity for erythromycin ion-pairs were evaluated. The interference from excipients commonly present in dosage forms and common degradation product was studied. The method is highly specific for the determination of stearate and succinate esters in dosage forms. The method has been compared to the official method and found to be simple, accurate (t-test) and reproducible (F-test). The developed method was applied for bulk drug, esters and some of their dosage forms without interferences from additives and excipients.

Spectrophotometric and conductimetric determination of dipyridamole in pure and dosage forms using chromotrope 2B and phosphotungstic acid

A Spectrophotometric method is proposed for determining dipyridamole in pure form and in pharmaceutical preparations. Chromotrope 2B was used as a charge-transfer complex forming agent with absorption maximum ≅ 40 nm red shifted relative to the chromotrope 2B itself. The variables affecting the formation of the C.T. complex were studied and optimized. Linear calibration graphs were obtained up to 60 μg ml−1 at room temperature. The method was found to be accurate, precise and can be successfully used for authentic and pharmaceutical preparations in the working range up to 600 μg.

Spectrophotometric Determination of Lignocaine in Pure Form and in Pharmaceutical Preparations

Two spectrophotometric methods have been developed for the determination of lignocaine in pure raw material or in formulated dosage form. One of these methods is based on the extraction of the ion-associate formed with reineckate salt by nitrobenzene or chloroform/acetone [solvent mixture, 1:1 (v/v)] and the absorbance is measured at 525 nm and at pH 5. Beer's law is obeyed in the range 0.2-2.0 mg/mL. The other method depends on the oxidation of lignocaine by Ce(IV), the excess of Ce(IV) is reacted with chromotrope 2B or chromotrope 2R where the red colour of the reagent decreases. The absorbance is measured at 510 and 530 nm and the methods are found useful in the concentration ranges 0.5-2.5 and 1.1-3.4 μg/mL, respectively. In another approach iron (II) is added to the excess Ce(IV) followed by the reaction with thiocyanate, salicylate or o-phenanthroline. The developed colours are measured at 450, 520 and 510 nm with concentration ranges 1.5-12.3, 1.8-10.6 and 0.5-4.3 μg/mL, respectively. It is evident that the use of the thiocyanate method is more preferable due to its wider usable concentration range.

Charge Transfer Complex Formation in Spectrophotometric Determination of Verapamil Hydrochloride

Two new spectrophotometric procedures for the determination of verapamil hydrochloride in pure as well as in pharmaceutical preparations were suggested. The methods are based on the formation of C.T. complexes with chromotrope 2B or chromotrope 2R azo dyes followed by extraction in chloroform and measuring the absorbances at 530 and 546 nm, respectively. Linear calibration graphs were obtained in the ranges 4.91–58.93 μg ml−1 verapamil hydrochloride. Variance coefficients of 1.07–3.85 and 1.09–4.10 were obtained for the verapamil tablets using C2R and C2B, respectively, whereas for the Isoptin tablets, the C.V. values were 1.66–5.08 and 1.89–4.6 using C2R and C2B, respectively. A recovery of 98–108% and 101–109% reflecting 92–99 and 91–99 accuracy % for C2R and C2B, respectively were recorded. Student t-test and F-test statistical treatments were applied for the results obtained by the two methods and compared with the official pharmaceutical method giving excellent agreement with 95% confidence. This elaborates these two methods for safety, accuracy and simple uses for quality control analysis of verapamil hydrochloride in its pure form as well as pharmaceutical preparations.

Spectrophotometric assay of cephalosporins in pharmaceutical products, using chromotrope 2B and chromotrope 2R

A simple, rapid and sensitive Spectrophotometric method is proposed for the determination of cephadroxil (I), cephalexin (II) and cephradine (III). The method is based on ion-pair complex formation between these derivatives and Chromotrope 2B (C2B) or Chromotrope 2R (C2R), to give a highly coloured radical anion. The coloured products are quantified spectrophotometrically at 542 and 564 nm for C2B and C2R, respectively. The optimization of the experimental conditions is described. The method has been used for the determination of 0.4–15, 0.4–14 and 0.4–18 μg/ml of drugs I, II and III, respectively. The accuracy of the method is indicated by the excellent recovery (100.0±1.7%) and the precision is supported by the low relative standard deviations ⩽ 1.5%. The sensitivity of the method is discussed and the results are compared with the official method. The interference from common degradation products and excipients was also studied. The proposed method was applied successfully to the determination of the different cephalosporins in dosage forms, with good precision and accuracy. The results were compared with those given by the official B.P. 1993 method.

On-line preconcentration of aluminium with immobilized Chromotrope 2B for the determination by flame atomic absorption spectrometry and inductively coupled plasma mass spectrometry

A new and rapid on-line preconcentration and matrix separation method is described for the determination of aluminium by flame atomic absorption spectrometry (FAAS) and inductively coupled plasma mass spectrometry (ICP-MS). The method is based on selective retention of aluminium in a microcolumn packed with Chromotrope 2B immobilized on AG 1-X8 ion exchange resin. All the variables that affect the efficiency of aluminium retention and elution from the microcolumn have been investigated. The resulting method is rapid, sensitive and selective. For collection times of 10 and 2 min at a flow rate of 1 ml min −1 the detection limits are 10 and 0.1 ng ml −1 for FAAS and ICP-MS, respectively. The proposed method, which is highly sensitive and selective, was successfully applied to determine aluminium in tap water and dialysis solutions.

On-line aluminium preconcentration on chelating resin and its FIA-spectrofluorimetric determination in foods and dialysis concentrates

A new, sensitive and rapid spectrofluorimetric flow-injection method, is presented for the determination of trace levels of aluminium based on the formation of a fluorescent complex between aluminium and 5,7-dibromo-8-quinolinol (DBQ) and its extraction into diethylether (λ exc = 400 nm, λ em = 525 nm). Experimental conditions such as pH, reagent concentration, flow-rates, sample volume, extraction coil length, etc., have been optimized for on-line and batch procedures. The detection limits are 1 ppb and 0.3 ppb for batch and on-line systems respectively. The coeflicient of variation is 3.0% at the 4 ppb level for the FIA system. To remove interferences and to preconcentrate aluminium, a chelating resin microcolumn which was able to selectively complex A1(III) and was obtained by immobilizing Chromotrope 2B on AG1-X8 ion-exchange resin, was incorporated into the FIA system. The proposed method was successfully applied to determine aluminium in tap water, food samples and dialysis solutions.

Sorption of copper, nickel and lanthanum on a strong-base anion exchanger containing Chromotrope 2B

The sorption of a number of metal ions on the strong-base resin AG 1 × 8 containing the azo-dye Chromotrope 2B has been studied using conventional analytical methods. While lead, cadmium, zinc and magnesium are not sorbed, copper, lanthanum and nickel are. The sorption of nickel was unexpected because complexation in water is negligible. In the resin phase a 1:2 complex was found. For copper both the 1:1 and 1:2 complexes are formed depending on the ligand concentration in the resin. Evidently, the high ligand concentration in the resin promotes the formation of the 1:2 complex. For lanthanum also 1:1 and 1:2 complexes are formed. The experimentally determined extraction coefficients can be related to the intrinsic formation constants with the aid of the Donnan equilibrium. A good agreement is found for the 1:1 complexes of copper and lanthanum, but not for the 1:2 complex of lanthanum, probably due to large differences in the activity coefficients.

Effects of competitive binding on the amperometric determination of copper with electrodes modified with chromotrope 2B

Electrodes modified with Chromotrope 2B incorporated by ion-exchange into a polycationic film of electropolymerized [Ru(v-bpy) 3] 2+ (v-bpy = 4-vinyl-4′-methyl-2,2′-bipyridyl) have been employed in the amperometric determination of copper in solution and exhibit very high sensitivity as well as linear calibration curves in the concentration range 7 × 10 −8−1 × 10 −4 M. The effects of competing ligands, including chloride, bromide, oxalate, ammonia, acetate, citrate, borate, humic and fulvic acids, or the presence of competing metal ions such as cobalt or nickel on the uptake of copper by the modified electrodes have also been studied. The presence of competing ligands or metal ions decreases the analytical signal due to copper incorporation. The magnitude of this effect is dependent on the relative strength of coordination of the competing ligands for copper ions or of Chromotrope 2B for the competing metals, and also on the concentration of the interferents. The relevance of this work to speciation studies is discussed.

On crystal growth of ammonium and potassium dichromate. A study of the shubnikov effect

AbstractGrowth and equilibrium forms of ammonium (A2/a) and potassium dichromate (P 1) have been calculated by means of the Fourier transform method of crystal morphology. Twin laws of potassium dichromate and heteroepitaxial intergrowth of both substances can be explained by partitions of space. According to Shubnikov the (001) planes of potassium dichromate crystals grown in aqueous solutions are always smooth, the parallel opposite planes, however, roughened. Wagner observed that this effect only occurs at temperatures shortly above or below 25 °C. The present investigation has shown that roughening of (001) appears at 25 °C after addition of potassium chromate to the potassium dichromate solutions. This means that the one‐sided intergrowth can be explained by a stereospecific adsorption of polychromates. Solution additions like potassium permanganate and Chromotrope 2B generate roughenings on both {001} faces. X‐Ray diffraction investigations can be interpreted in such a way that the intergrown plates are mirror symmetric oriented to two planes being normal to the a‐ and b‐axes. This is in accordance with repeated formation of intergrown plates.

Separation of trace amounts of aluminium on a strong anion-exchange resin loaded with a sulphonated azo dye

The sulphonated azo dye Chromotrope 2B is sorbed quantitatively by the strong anion exchanger AG 1-X8. A chelating resin is obtained, which is able to sorb aluminium from aqueous solutions selectively. The distribution equilibria were investigated under different conditions and interpreted on the basis of a Donnan equilibrium based model for the resin. A separation and pre-concentration method for aluminium in natural waters is proposed, based on the use of the modified resin in a column at ambient pressure. The selectivity with respect to other metal ions was good; this was to be expected because Chromotrope 2B in solution is also selective for aluminium. Recoveries of 100 ± 1% were obtained, with a pre-concentration factor of 50, at a total aluminium concentration of 2 × 10–6 mol kg–1.

Metal chelates of lanthanoids in aqueous solution and their analytical applications

AbstractA detailed study on the composition, stability and analytical applications of Rare Earth chelates with Aluminon, Chrome Azurol S, Thoron, Chromotrope 2B and Alizarin Red S have been described. The composition have been ascertained spectrophotometrically using the Method of Continuous Variations, Mole Ratio Method and the Slope Ratio Method. The range for adherence to BEER'S law, sensitivity and other optimum conditions required in the analytical applications have been described.

Chromotrope 2B as a chromogenic agent for the photometric determination of the rare earths

Chromotrope 2B as a chromogenic agent for the photometric determination of the rare earths

P-Nitrobenzene Azochromotropic Acid (Chromotrope 2B) as a Colorimetric Reagent for Thorium

Abstract A method for the colorimetric determination of thorium with Chromotrope 2 B has been described. The composition of the coloured chelate (λmax 550 mμ) is Th(Ke)2. The system adheres to Beer’s law from 074 p.p.m. to 16.6 p.p.m. of thorium between pH 3.0 and 6.5 at all temperatures from 5 to 95°C. The sensitivities are 0.232 γ/cm2 (Sandell) and 2.32 γ/cm2(practical) based on an absorbance of 0.01 unit at 580 mμ. The interference of some cations and anions has also been reported.

Micro Determination of Lanthanum (III) Using p‐nitrobenzene azochromotropic acid (chromotrope 2B) as a chromogenic reagent

Abstractp‐nitrobenzene azochromotropic acid (Chromotrope 2 B) forms a 1 : 1 reddish violet chelate (λmax 540 mμ) with lanthanum(III) at pH 6.0. The value of stability constant expressed as log K = 4.5 and 4.9 as determined by two different methods. The colour of the chelate is stable over a wide range of temperature (0–100°) between pH 4.0 and 7.0. The system obeys BEER'S law over a range of 0.34 p. p. m. to 16.7 p. p. m. of lanthanum.

Composition and Stability of Lanthanum(III) -p-nitrobenzeneazochromotropic Acid (Chromotrope 2B) Chelate in Solution

A detailed study of the composition and stability of lanthanum(III)-p- nitrobenzeneazochromotropic acid (chromotrope 2B) chelate was made spectrophotometrically. The chelate is reddish violet in color ( lambda /sub max/ at 540 m mu ). The composition, as determined by different methods, is 1: 1 (metal: chelating agent). The chelate is stable between pH 5.0 and 12.5. The values of log K, as determined by two different methods, are 4.6 plus or minus 0.1 and 4.9 plus or minus 6.18 respectively at 25 deg and at pH 6.0. (auth)