Spectrophotometric and derivative spectrophotometric determination of nickel with hydroxynaphthol blue

The reaction of nickel(II) cation with hydroxynaphthol blue (HNB) in aqueous media at pH 5.2–6.0 results in a red complex that is stable for at least 2h. Beer's Law is obeyed up to 3.2 g/ml of nickel(II) with an apparent molar absorptivity of 1.38 × 10⁴l/mol/cm at 563 nm. This paper proposes procedures for nickel determination by ordinary and first-derivative spectrophotometry. The results demonstrate that the linear dynamic range is 0.08–3.20 g/ml with a limit of detection of 23 ng/ml for ordinary spectrophotometry, compared with 21–800 ng/ml and 6 ng/ml, respectively, for first-derivative spectrophotometry. Calcium(II), magnesium(II), barium(II), strontium(II), cadmium(II), lead(II), manganese(II), bismuth(III) and molybdenum(VI) ions do not interfere for at least 1001 mass ratios. The main interferents are cobalt(II), titanium(IV), aluminium(III), mercury(II) and copper(II). The interferences of titanium(IV), aluminium(III), zirconium(IV) and iron(III) can be masked by fluoride and mercury(II) and copper(II) with thiosulfate or thiourea. The derivative method is applied to nickel determination in standard brasses and the results demonstrate that there is no significant difference between the results and certified values at the 95% confidence level.     

Spectrophotometric and analogue derivative spectrophotometric determination of ultramicro amounts of cadmium with cationic porphyrins

alpha,beta,gamma,delta-Tetrakis(1-methylpyridinium-3-yl)porphine [T(3-MPy)P] and alpha,beta,gamma,delta-tetrakis(1-methylpyridinium-4-yl)porphine [T(4-MPy)P] have been found to react rapidly with cadmium to give coloured complexes in weakly alkaline media at room temperature. Simple and practical methods for the determination of cadmium at ng/ml levels by conventional and analogue derivative spectrophotometry have been proposed. The analogue method gives higher sensitivity. T(3-MPy)P gives higher sensitivity than T(4-MPy)P. The interference of various foreign cations and anions has also been examined and in many cases eliminated or reduced. Adsorption of the porphyrins and their cadmium complexes onto the glassware, which is usually observed under the conditions of reaction and causes significant errors in the determination, can be suppressed almost completely by addition of fairly large amounts of a salt such as sodium chloride.     

Sensitive and selective spectrophotometric determination of aluminium with Chrome Fast Pure Blue B and cetyltrimethylammoniumbromide

Summary A new sensitive and selective method for determining aluminium with Chrome Fast Pure Blue B and cetyltrimethylammoniumbromide is described. Lambert-Beer's law is strictly obeyed between 0.0102 and 0.0816g/ml in the final dilution. The maximum absorbance is shown at 645 nm. The molar absorbance is 1.23×10⁵ l mol^–1 cm^–1. 44 ions have been studied concerning their interference. The determination of aluminium in steels, soil and ashes of plants is described.We thank FINEP and CNPg of Brazil which made these projects possible.     

Spectrophotometric determination of aluminium with stilbazo

The use of stilbazo as a spectrophotometric reagent for aluminium has been investigated. The reagent forms a stable coloured complex with aluminium showing an absorption maximum at 500 mμ. The system obeys Beer's law from 0.1–0.8 p.p.m. aluminium. The molar extinction coefficient and the stoichiometric composition of the coloured complex have been determined.     

Spectrophotometric and derivative spectrophotometric determination of copper (II) with dithizone in aqueous phase

A Spectrophotometric and derivative Spectrophotometric study of Cu-dithizonate complex in aqueous phase in the presence of Triton X-100, a neutral surfactant, is reported. The system obeys Beer's law between 1.0 × 10^–6–9.0 × 10^–6 mol/l of Cu²⁺; detection limit is 12 ng/ml. The molar absorption coefficient, specific absorptivity and Sandell's sensitivity of the complex are 3.06 × 10⁴ 1 mol^–1 cm^–1, 0.4825 ml g^–1 cm^–1 and 2.1 × 10^–3 g cm^–2, respectively. The conditional stability constant of the 1 2 complex, calculated considering simultaneously existing equilibria, has been found to be 1.73 × 10¹¹ I² mol² (I = 0.07, pH 1.4, temperature = 10 °C). Absorption studies in the derivative mode have been carried out to determine the absorption maximum of the complex and to overcome interference due to the presence of certain metal ions. The method has been validated by determination of copper in beers, wines, human hair, goat liver and fly ash samples.     

Spectrophotometric determination of aluminium with Chromal Blue G in the presence of cetyltrimethylammonium chloride

Summary Spectrophotometric Determination of Aluminium with Chromal Blue G in the Presence of Cetyltrimethylammonium Chloride Chromal Blue G (C. I. 43835) in the presence of cetyltrimethylammonium chloride is proposed for the spectrophotometric determination of microgram amounts of aluminium. The stoichiometric ratio of aluminium to Chromal Blue G is 14. Beer's law is obeyed from 0.01 to 0.16 ppm of aluminium. The molar absorptivity is 1.62×10⁵1·mole^–1·cm^–1 at 660 nm.     

Spectrophotometric determination of aluminium with chlorophosphonazo I

Aluminium reacts with Chlorophosphonazo I at pH 4-6 to form a water-soluble 1:1 red-violet complex. The absorption maximum is at 610 nm and the apparent molar absorptivity is 1.96 x 10(4) l.mole(-1).cm(-1). The apparent instability constant has been calculated to be 1.8 x 10(-4). The colour of the complex is stable for 24 hr. Beer's law is obeyed over the concentration range up to 0.8 mug ml . Titanium and zirconium interfere seriously.     

Spectrophotometric determination of aluminium and nickel

A simple spectrophotometric method, based on the complexes with xylenol orange (XO) and EDTA, is presented for the rapid determination of aluminium and nickel, respectively, in synthetic samples of hydrotalcite. The method only requires the solubilization in sulphuric acid of the inorganic material before the ligand addition. Under optimum conditions, the complexes Al-XO and Ni-EDTA showed maximum absorption at 554 nm and 380 nm, respectively. The method obeyed Beer's law in the concentration range 0.14-1.8 microg mL(-1) of aluminium, and 30-2730 microg mL(-1) of nickel. Molar absorptivities were 2.45 x 10(4) and 14.85 L mol(-1) cm(-1) while Sandell's sensitivities were 1.1 x 10(-3) and 3.9 microg cm(-2) for aluminium and nickel, respectively. The standard addition technique was used and the recoveries obtained revealed that the proposed procedure shows good accuracy.     

Spectrophotometric determination of aluminium in steel with stilbazo

A procedure for the determination of aluminium in steel is described. Aluminium is separated from iron and interfering elements by ion exchange in concentrated hydrochloric acid solution, and finally determined spectrophotometrically with stilbazo.     

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.     

Spectrophotometric determination of Diclofenac sodium with Methylene Blue

A sensitive spectrophotometric method was established for the determination of Diclofenac sodium (DS) with Methylene Blue (MB) as analytical reagent. It was found that DS reacts with an excess of MB in the pH range 9.2-9.4, to form a chloroform-extractable blue ion-association complex. Good agreement with Beer's law was found in the range of DS concentrations of 0.8-6.4 mug/ml with a detection limit of 0.37 mug/ml. The method was applied for the determination of DS in various tableted forms with a good precision.     

Spectrophotometric determination of aluminium by morin

A direct spectrophotometric method for the determination of aluminium with morin has been developed. Morin reacts in slightly acidic 50% ethanolic media (0.0001-0.0015 M H(2)SO(4)) with Al to give a deep-yellow chelate which has an absorption maximum at 421 nm. The average molar absorptivity and Sandell's sensitivity were found to be 5.3 x 10(3) l mol(-1) cm(-1) and 5 ng of Al cm(-2), respectively. The reaction is instantaneous and absorbance remains stable for 48 h. The colour system obeys Beer's law from 10 ng ml(-1) to 5.0 mug ml(-1) of Al; the stoichiometric composition of the chelate is 2:3 (Al:morin). The interference from over 50 cations, anions and complexing agents has been studied at 0.1 mug ml(-1) of Al. The method was applied successfully to some certified reference material samples (alloys and steels), environmental waters (inland and surface), biological samples (human blood, urine and gallstone), soils and complex synthetic mixtures.     

Simultaneous spectrophotometric determination of Thymol Blue, Semi-Methylthymol Blue and Methylthymol Blue

A direct spectrophotometric method for the simultaneous determination of Thymol Blue, Semi-Methylthymol Blue (SMTB) and Methylthymol Blue (MTB) in mixtures in the presence of other components usually found in synthetic SMTB and commercial MTB is presented. The method for selecting the most advantageous conditions for the spectrophotometric determination of the three dyes in different mixtures is given. A graphical version of the method is useful for monitoring syntheses of SMTB and MTB.     

Catalytic spectrophotometric determination of trace aluminium with indigo carmine

A new catalytic spectrophotometric method is described for the determination of trace amounts of Al(III). The methods based on catalytic action of Al(III) on the oxidation of indigo carmine (IC) by ammonium persulfate in hexamethylene tetramine-hydrochloric acid ((CH2)6N4-HCl) buffer medium (pH 5.4) and in the presence of surfactant-TritonX-100. The effects of some factors on the reaction speed were investigated. Aluminium concentration is linear for 0-1.2x10(-7) g/ml in this method. The detection limit of the proposed method is 1.96x10(-8) g/ml. Most of the foreign ions except for Cu(II), Fe(III) do not interfere with the determination, and the interference of Cu(II) and Fe(III) in this method can be removed by extraction with sodium diethyldithiocarbamate-carbon tetrachloride (DDTC-CCl4). This system is a quasi-zero-order reaction for Al(III), but it is a quasi-first-order reaction for IC. The apparent rate constant is 2.62x10(-5) s-1 and the apparent activation energy is 6.60 kJ/mol in the system. The proposed method was applied to the determination of trace aluminium(III) in real samples with satisfactory results.     

Spectrophotometric determination of boron with an azomethine H derivative

Summary An azomethine H derivative, 1-(2,4-dihydroxybenzylidene-amino)-8-hydroxynaphthalene-3,6-disulphonic acid (azomethine HR) was examined and proposed as a spectrophotometric reagent for boron, as compared with azomethine H. Azomethine HR reacts with boron in aqueous solution (pH 7.5) to form a yellow complex having an absorption maximum at 425 nm. The sensitivity is 3.5-fold greater than with azomethine H when the same reagent concentration is applied. Basic conditions for the determination of boron have been worked out. The method is applicable to sea and hot spring waters. The standard deviation is ±2.1%.

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Spektralphotometrische Borbestimmung mit einem Azomethin H-Derivat

     

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 magnesium in aluminium alloys

The determination of magnesium in aluminium alloys by a differential spectrophotometric method is describcd. Magnesium is separated and the absorbance of its coloured complex with Eriochrome Black T measured.     

Spectrophotometric and derivative spectrophotometric determination of iron by extraction of the iron(II)-TPYZ-picrate ion-association complex

A solvent extraction-spectrophotometric determination of microamounts of iron has been developed, based on the formation of an ion-association complex of iron(II) with 2,4,6-tris(2'-pyridyl)-1,3,5-triazine as primary ligand and picrate as counter-ion, which is extracted into 1,2-dichloroethane. The complex is formed at pH 4.0-7.0 and the iron concentration can be determined by measuring the absorbance directly in the organic phase. The apparent molar absorptivity is 2.2 x 10(5) l.mole(-1).cm(-1). As the method is practically free from interferences it was applied to the determination of iron in different biological and inorganic samples. Although the proposed method is very sensitive it can be further sensitized by employing the derivative spectrophotometric technique.     

Spectrophotometric determination of aluminium with ferron and a quaternary ammonium salt

The reproducibility of the ferron method for aluminium has been greatly improved by the addition of cetyltrimethylammonium chloride (CTMAC). The improvement is attributed to reduction of the reagent blank and increased stability of Al(ferron)(3-)(3). The aluminium-ferron complex formed in the presence of CTMAC has an absorption peak at 385 nm. The interference from iron can be eliminated by application of a correction based on measurement at two wavelengths.     

Spectrophotometric determination of hydrogen peroxide with leuco Patent Blue Violet

Hydrogen peroxide (1 × 10^?7?10^?5 mol dm^?3) was determined in aqueous solution using leuco Patent Blue Violet and peroxidase. The reagent can also be applied in the same concentration range to the ethyl acetate extraction method described previously. This allows hydrogen peroxide to be determined in the presence of a variety of species which interfere in the direct method. A reagent consisting of leuco Patent Blue Violet, peroxidase, glucose oxidase and mutarotase was also applied to the determination of glucose.