Spectrophotometric determination of cationic surfactants by formation of ternary complexes with Fe(III) and chrome azurol

An extraction-free spectrophotometric method for the determination of cationic surfactants, such as cetylpyridinium chloride, cetyltrimethylammonium bromide and zephiramine is proposed, which is based on the formation of ternary complexes with Fe(III) and chrome azurol S. The molar ratio of the complex is 2:1:1 (Fe(III):chrome azurol S: cationic surfactant). The method is simple, rapid and sensitive, giving an apparent molar absorptivity of 4.5×10⁴ L·mol^?1-cm^?1 and a linear range of 0.1–6.0 μmol/L cationic surfactants. The total cationic surfactant content can be determined directly in aqueous solutions by measuring the absorbance at 680 nm (pH 5.8). The method has been successfully applied to water samples.     

Spectrophotometric determination of iron(III) with chrome azurol s or eriochrome cyanine r and some cationic surfactants

Sensitive spectrophotometric methods for the determination of iron(III), based on ternary complexes with a triphenylmethane reagent, chrome azurol S (CAS) or eriochrome cyanine R (ECR), and cetyltrimethylammonium (CTA) or cetylpyridinium (CP) ions, are described. For the system Fe—CAS—CTA, the molar absorptivity is 1.35 × 10⁵ l mol^-1 cm^-1 at 645 nm; for Fe—ECR—CTA it is 1.28 × 10⁵ l mol^-1 cm^-1 at 635 nm. Maximum absorbance is attained (at about pH 4) when the molar ratio (to iron) or CAS or ECR is about 20 and that of CTA or CP is 60–80. Citrate, tartrate, oxalate and EDTA interfere. Interference by metals (e.g. Be, Al, Ga, In, Sc, Zr, Th) can be eliminated by preliminary extraction of iron(III) as thiocyanate complex. The method was successfully applied to determining traces of iron in analytical-grade sodium hydroxide.     

The Spectrophotometric Determination of Sc in Eriochrome Canine R(Chrome azurol s)- Phosphatidl Choline System

Abstract

Eriochrome cyanine R(chrome azurol S) is used as a color reagent to determine Sc in the presence of phosphatidyl choline, σ = 3.7 × 10⁴ (4.5 × 10⁴). This method has been connected to extraction separation to determine Sc in the presence of rare earth elements, and good results have been obtained.

Phosphatidyl choline(PC) is a biochemical reagent, which can be used as a surfactant. It has been reported that chrome azurol S(CAS) can be used to determine Be in the presence of PC¹ but it has not been reported that eriochrome cyanine R(ECR) and CAS can be used to determine Sc in the presence of PC. This paper has put forward a method by which Sc can be determined. ECR (CAB) has been used as a color reagent and PC as a surfactant. Conditional experiments have been made and this method has been connected to extraction separation. Tributyl phosphate (TBP) extracts Sc from rare earth elements to make a determination and good results have been obtained.     

Spectrophotometric determination of titanium with Chrome Azurol S (or Eriochrome Cyanine R) in the presence of some cationic surfactants

A new sensitive spectrophotometric method for titanium determination, based on the ternary Ti-Chrome Azurol S (CAS)-cetyltrimethylammonium (CTA) system, was developed. The molar absorptivity is 7.3 × 10⁴ liters mol^?1 cm^?1 at λ_max = 565 nm. The maximum absorbance is attained in 5 min at pH 1.3 ± 0.1 and at CAS and CTA concentrations of 1.5 × 10^?4 and 5 × 10^?4M, respectively. Zirconium and hafnium in the presence of ascorbic acid are the only interfering metals. Hydrogen peroxide and EDTA interfere with the titanium determination as well. The proposed method was applied to the determination of titanium (about 1 × 10^?2%) in aluminum metal. The method, based on the Ti-Eriochrome Cyanine R-CTA system, is similar to the above method. Among other cationic surfactants, cetylpyridinium chloride (CP) and zephiramine were examined. The color effects when using CP, and especially zephiramine, are worse than in the presence of CTA.     

Spectrophotometric determination of aluminium with chrome azurol s

A comprehensive investigation of the spcctrophotometric determination of aluminium with chrome azurol S is described. No heating is required for colour formation, and the method is considerably more reproducible and selective than either the eriochrome cyanine R or aluminon methods. In the presence of suitable masking agents, only Be²⁺, Zr⁴⁺, and F-cause serious interference. A molar absorptivity of 21,500 at 567.5 mμ was found for the aluminium-chrome azurol S lake, with a relative standard deviation of ± 0.4% at the 20 μg Al level. Beer's law is obeyed from 0 to 1.2 mg Al/ml.     

Estimation of free acidity in some hydrolysable metal ions present in reprocessing streams by fiber optic aided spectrophotometry

A fiber optic aided spectrophotometric technique has been developed for the determination of free acidity in nuclear fuel reprocessing streams. In this method, nitric acid forms yellow colour complex with chrome azurol s. The system obeys Lambert–Beer’s law at 542 nm in the range of acidity 4–14 M. The molar absorption coefficient (ε) and Sandell’s sensitivity (S) of complex are 5.23 × 10³ L.mol^?1.cm^?1 and 1.91 × 10^?4 µg/cm² respectively. Relative standard deviation is less than 1 % and correlation coefficient is 0.999. Results of the present method are in good agreement with those obtained by the standard procedure.     

Flow-injection spectrophotometric determination of aluminium based on chrome azurol S and cetylpyridinium chloride

Acidic aluminium solutions (120 μl) are injected into a buffered (pH 5.7) carrier stream and merge with a chrome azurol S/cetylpyridinium chloride stream; a 2.25-m reaction coil is used with a total flow rate of 4 ml min ^?1. Ethanol (30% v/v) in the reagent stream enhances the absorbance of the ternary complex; the molar absorptivity is then 1.34×10 ⁵ l mol ^?1 cm ^?1 at 625 nm. Calibration is linear over the range 0–400 ng ml^?1 aluminium; the limit of determination is 5 ng ml ^?1. Iron is masked in the usual way; fluoride is tolerated at ˇ1 mg l ^?1. The injection rate is about 45 h^?1. The procedure appears to be applicable to tap water.     

Sensitive spectrophotometric determination of gallium with bromopyrogallol red in the presence of surfactants

Gallium in the presence of surfactants (NTGE and CTA) forms with BPR a violet ternary complexes with λ_max at 615 and 625 nm, respectively, with molar absorptivities of 7.0 × 10⁴ and 1.3 × 10⁵ liters mol^?1 cm^?1. These complexes can be advantageously used for the determination of gallium. The molar ratio of gallium to BPR, which is 1:1 in the binary complex, increases to 1:3 in the ternary complex. The presence of surfactants changes the number of BPR molecules bonded to gallium. This is the main factor in the increase in color intensity. Numerous metals interfere. Gallium can be separated by extraction of gallium from 7 M hydrochloric acid with diisopropyl ether.     

High Sensitive and Selective Spectrophotometric Determination of Aluminium after Collection on a Membrane Filter Using 2,3‐Dichloro‐6‐(3‐carboxy‐2‐hydroxy‐1‐naphthylazo)quinoxaline and Zephiramine

Abstract

A high sensitive and selective spectrophotometric method for the determination of aluminium(III) using 2,3‐dichloro‐6‐(3‐carboxy‐2‐hydroxy‐1‐naphthylazo)quinoxaline (DCHNAQ) and zephiramine (zeph) is described. The formed ion pair precipitate between zephiramine and perchlorate ions is effective for the enrichment of aluminium(III) on a membrane filter as its ternary complex with DCHNAQ and zephiramine. The solid–state absorbance of the complex on the membrane filter is measured at 655 nm against a blank thin layer and the difference is calculated. The colour system obeys Beer's law from 5.0–150 ng ml^?1 of aluminium. The detection and quantification limits were calculated. The relative standard deviation for 60 ng of aluminium(III) in 20‐ml sample volume amounts 0.84% (n=10). A ligand buffer solution, composed of transcyclohexane‐1,2‐diaminetetraacetic acid with an excess of zinc(II), is effective for masking interferences from foreign ions, particularly iron(III). The proposed method was applied successfully to tap and environmental water, biological (human blood, urine, and gallstone), and soil samples.     

A kinetic determination of ultramicroquantities of some biologically active substances

A new kinetic method for the determination of ultramicroquantities of adrenaline, noradrenaline, thyroxine, and 5-hydroxytryptophan is presented. The method is based on the effect of these organic substances on the oxidation of pyrocatechol violet with hydrogen peroxide, catalyzed by Cu(II) ions.In order to find out the experimental conditions under which this effect is optimum, the kinetics of the above-mentioned indicator reaction in the presence of the compounds to be determined was studied in detail.Adrenaline and noradrenaline were determined at concentrations ranging from 2.0 × 10^?6 to 8.0 × 10^?6M, thyroxine at concentrations varying from 1.0 × 10^?6 to 10.0 × 10^?6M, and 5-hydroxytryptophan over the concentration range 7.7 × 10^?7–32.0 × 10^?7M. In these determinations the standard deviation was lower than 10%.     

2,2′-Dihydroxybenzophenone thiosemicarbazone as a spectrophotometric reagent for the determination of copper,cobalt, nickel,and iron trace amounts in mixtures without previous separations

2,2′-Dihydroxybenzophenone thiosemicarbazone forms complexes with Cu(II) (λ_max = 385 nm, ? = 8.60 × 10³ liter · mol^?1 · cm^?1); Ni(II) (λ_max = 380 nm, ? = 15.4 × 10³ liter · mol^?1 · cm^?1); Co(II) (λ_max = 380 nm, ? = 12.3 × 10³ liter · mol^? · cm^?1); and Fe(III) (λ_max = 365 nm, ? = 7.9 × 10³ liter · mol^?1 · cm^?1) and have been applied to the analysis of these metal ions in binary, ternary, and quaternary mixtures. The determination procedures are based exclusively on the different pH values of the formation complexes, hence the extraction step is not necessary.     

Spectrophotometric determination of aluminum with bromopyrogallol red in the presence of surfactants

Spectrophotometric methods are described for the determination of microgram amounts of aluminum based on the formation of a ternary complex between the metal, bromopyrogallol red, and cetyltrimethylammonium bromide or nonylphenol tetradecaethylene glycol ether. The complexes have absorbance maxima at 627 and 612 nm, respectively, with molar absorptivities of 5.0 × 10⁴ and 2.2 × 10⁴ liter mol^?1 cm^?1. Numerous metals interfere. Aluminum can be easily separated by extraction of interfering ions with cupferron.     

Effects of added metal ions on the interaction between polyvinylpyrrolidone and azo dyes carrying hydroxyl groups

The extent of binding of chrome violet, which is a monoazo dye and involves two hydroxyl groups in o and o′ positions to azo group, by polyvinylpyrrolidone is markedly enhanced in the presence of Co²⁺ ion. The amount of binding in the presence of 1 × 10^?4 mol/L of Co²⁺ ion increases by a factor of about 10 compared to that in the absence of the metal ion. Ni²⁺ and Zn²⁺ ions do not perceptively influence the binding affinity of the dye. Cu²⁺ ion, in contrast, suppresses the binding. To investigate further the action of added metal ions, a cobalt–complex dye was prepared and its binding property for the polymer was compared to that of chrome violet in the presence of metal ions. Some possible mechanisms for the enhancement of chrome violet binding by the addition of Co²⁺ ion are described.     

Spectrophotometric study of the copper(II)-2,2′-dipyridyl-2-pyridylhydrazone complex formation

The reaction of copper(II) ions with 2,2′-dipyridyl-2-pyridylhydrazone (DPPH) has been studied. Two copper complexes were found to be formed. One at pH 6.5 to 8.5 and the other at pH 11.9 to 12.6 with molecular extinction coefficients of 1.9 × 10⁴M^?1 · cm^?1 at the absorption maximum of 478 nm and 3.8 × 10⁴M^?1 · cm^?1 at 448 nm, respectively. A sensitive spectrophotometric procedure for the determination of copper at less than a 1-ppm level is proposed.     

Spectrophotometric Determination of Osmium at the PPB Level Using Pyrocatechol and Hydroxyamidine

Abstract

A sensitive method for the spectrophotometric determination of osmium at the ppb level is described. The method is based on the formation of a brown-coloured complex by heating the reaction mixture containing Os(VIII), pyrocatechol and a hydroxyamidine at pH 8.5 over a boiling water bath, with subsequent extraction of the coloured species into chloroform. The molar absorptivity of the coloured species with N-hydroxy-N,N′-diphenylbenzamidine is 3.95 × 10⁶ 1 mol^?1 cm^?1 at λ_max = 410 nm. The method is free from interferences for almost all ions tested.     

Bis[2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulpho propylamino)phenolato]cobaltate(III) as a counter ion for the extraction and spectrophotometric determination of long-chain quaternary ammonium salts and tertiary alkylamines in the presence of each other

The singly charged complex anion bis[2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulphopropylamino)phenolato]cobaltate(III) is intensely purple-violet and is stable over the pH range 1–13. Its absorption spectrum remains the same over this pH range. At pH2, it forms extractable ion pairs with long-chain quaternary ammonium ions and protonated alkylamines. Only the quaternary ammonium ions are extracted into chloroform at pH 11, hence separate extractions allow both types to be determined. The absorbance of the organic phase is measured at 594 nm. The apparent molar absorptivity is 7.0 × 10⁴ l mol^?1 cm^?1. Calibration graphs for zephiramine, benzethonium and hexadecylpyridinium ions are linear over the range 0.1–2 × 10^?6 M. The only interference found was from anionic surfactants. The method is applied to hair and fabric conditioners.     

Determination of Thallium in Soil

Abstract

A new spectrophotometric method is described for the determination of thallium in soil by extraction of Tl(III) with a toluene solution of N,N′-diphenylbenzamidine after acidification with 0.2–4.0 M HCl, and reaction of the extract with Crystal violet in the presence of 0.01–0.8 M HCl. The value of molar absorptivity of Tl(III)-X-CV complex (where X = Cl or Br; CV = Crystal violet) in toluene is 7.00 × 10⁴ 1 mole^?1 cm^?1 at the absorption maximum of 610 nm. The detection limit of the method is 20 ng ml^?1. The present method is free from interference of almost metal ions commonly associated with Tl. The method has been applied for analysis of the metal to soils.     

Flow-injection spectrophotometric determination of aluminium in water with pyrocatechol violet

Optimum conditions for the adaptation of the spectrophotometric pyrocatechol violet method for aluminium to a flow-injection system are described. The detection limit is 3 μg Al l^?1 and calibration graphs are linear up to 3 or 10 mg l^?1 (with 200-μl or 10-μl injection loops, respectively). The relative standard deviation is 〈 2% at 0.1 mg Al l^?1. Potential interferences of 40 common inorganic ions and of 20 organic substances, including fulvic acid, are reported. With the use of conventional masking agents and predigestion of samples with high organic content, the method is suitable for determining total aluminium in natural waters.     

Spectrophotometric determination of aluminium and gallium with pyrogallol red and cetyltrimethylammonium ions

Spectrophotometric methods are described for the determination of microgram amounts of aluminium and gallium based on the formation of a ternary complex between the metal, pyrogallol red, and cetyltrimethylammonium bromide. The complexes have absorbance maxima at 610 and 615 nm, respectively, with molar absorptivities of 4.8 × 10⁴(Al)and 1.0 × 10⁵ liter mol^?1 cm^?1 (Ga). Numerous metals interfere. Gallium can be separated by extraction of gallium from 7 M hydrochloric acid with di-isopropyl ether. However, aluminium can be separated by extraction of interfering ions with cupferron.     

Extraction and spectrophotometric determination of trace amounts of tin(II) with diphenylglyoxal bis(2-hydroxybenzoylhydrazone)

Diphenylglyoxal bis(2-hydroxybenzoylhydrazone) has been used as a sensitive reagent for the spectrophotometric determination of tin. This reagent forms an orange-yellow complex with stannous ion at pH 3.5–7.0 (λ_max = 455 nm, ? = 2.25 × 10⁴ liter mol^?1/cm^?1 while no reaction is observed with quadrivalent tin. The colored complex extracted into isobutyl methyl ketone has been used for the spectrophotometric determination of trace amounts of tin(II). The molar absorption in the organic solvent is 3.54 × 10⁴ liter mol^?1 cm^?1 and the compound shows its maximum absorbance at 455 nm. The interferences of foreign ions have been determined.