Zirconyl-alizarin blue s complex a spectrophotometric study

Alizarin blue S in 0.5N hydrochloric acid and 10% acetone gives a coloured complex with zirconium salts, which is used for the estimation of zirconium. Measurements were made at 625 mμ and the interference of several cations and anions was studied     

The thorium-apans complex : A spectrophotometric study

The compound formed from thorium and Apans has been studied by spectrophotometric methods and shown to contain thorium and reagent in the ratio 1 : 2. The apparent stability constant of this complex has been measured as 1.4 ± 0.1$\text{.}\text{?}$10¹⁰     

Analytical application and spectrophotometric study of the scandium-indoferron complex

A new spectrophotometric method for microgram amounts of scandium with indoferron is described. The molar absorptivity is 960 l.mole⁻¹.mm⁻¹ at 600 nm. Uranium and the rare earths do not interfere, if present in amounts less than 50 μg. Scandium in silicate rocks can be determined by the procedure after separation of the scandium by a three-stage ion-exchange Chromatographic technique. The acid dissociation constants of indoferron and conditional formation constants of the 1:2 complex have been determined spectrophotometrically.     

A spectrophotometric study of cobalt complex with thio-violuric acid

Summary A water soluble dark yellow complex formed by cobalt with thiovioluric acid exhibits an absorption maximum at 425 nm. The composition of the complex comes out to be 13 as revealed by Job's method of continuous variations and mole ratio method. The optimum p_H range for complete formation of a complex is 7.1 to 9.3. Its sensitivity has been found to be 0.0011g Co/cm² at 425 nm. The effect of various foreign ions in the determination of cobalt has also been investigated.

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Zusammenfassung Ein wasserlöslicher, dunkelgelb gefärbter Kobaltkomplex mit Thioviolursäure hat das Absorptionsmaximum bei 425 nm. Mit den üblichen Methoden wurde für dessen Zusammensetzung das Verhältnis 13 ermittelt. Das optimale p_H-Bereich für die Komplexbildung liegt zwischen 7,1 und 9,3. Die Empfindlichkeit der Reaktion beträgt 0,0011g Co/cm² bei 425 nm. Der Einfluß verschiedener Fremdionen wurde untersucht.

     

Uranyl oxinates a spectrophotometric study

From spectrophotometric studies of the 2- and 3-oxinates of uranyl in various non-aqueous solvents it has been shown that the two complexes possess, different structures. The change in absorption of oxine in acidic and alkaline solutions has been explained.     

The edta complex of platinum(IV): a titrimetric and spectrophotometric study

Platinum in the form of hexachloroplatinate(IV) reacts slowly with EDTA in a 1:1 mole ratio. At the concentration level used (a few mg per 50–75 ml), favorable conditions were solution of pH 3–4.5, and 3–8-fold molar excess of EDTA. Complete reaction required heating at 100° for 1.5–2 h. The reaction rate was retarded by acetate ion, but not by nitrate or sulfate. Titrimetric determination of platinum was accomplished by addition of excess standard EDTA, buffering to pH 3–4.5, heating the mixture at 100° for 1.5 h, buffering to pH 5.3 with acetic acid-acetate, and back-titrating with zinc acetate to a xylenol orange end-point. Blank corrections were necessary to compensate for trace metal impurities in the water and/or reagents. Determinations of 0.4–3 mg of platinum per 50 ml were accurate to ± 1.3% standard deviation. Both titrimetric and spectrophotometric evidence ruled out the possibility of reduction of platinum(IV) by EDTA. Titrimetric methods showed the complex to be PtCl₄HY^3-, where Y is the deprotonated EDTA.     

Rank annihilation factor analysis for spectrophotometric study of complex formation equilibria

The use rank annihilation factor analysis (RAFA) for spectrophotometric studies of complex formation equilibria are proposed. One-step complex formation and two successive and mononuclear complex formation systems studied successfully by proposed methods. When the complex stability constant acts as an optimizing object, and simply combined with the pure spectrum of ligand, the rank of original data matrix can be reduced by one by annihilating the information of the ligand from the original data matrix. The residual standard deviation (R.S.D.) of the residual matrix after bilinearization of the background matrix is regarded as the evaluation function. The performance of the method has been evaluated by using synthetic data. For two-step successive complex formation systems, the effects of noise level and equilibrium constants K₁ and K₂ on output of algorithm are investigated. The applicability of method for resolving the two-step successive complex formation systems with full spectral overlapping of two complex species also is shown. Spectrophotometric studies of murexide-calcium, dithiazone-nickel and methyl thymol blue (MTB)-copper are used as experimental model systems with different complexation stoichiometries and spectral overlapping of involved components.     

A potentiometric and spectrophotometric study of gallium—benzohydroxamic acid complex formation

The complex formation of gallium with benzohydroxamic acid has been studied by potentiometry and spectrophotometry. Three successive complexes, GaL²⁺, GaL₂⁺, and GaL₃, are formed. The stability constants, log β₁, β₂, and β₃ , are 9.2 ± 0.1, 18.0 ± 0.1 and 25.3 ± 0.1, respectively, in 3 M NaClO₄ at 25°C.     

Extractive spectrophotometric determination of molybdenum as a thiocyanate-2-acetylpyridinethiosemicarbazone complex

A new spectrophotometric method for the determination of molybdenum is based on the extraction of the orange red molybdenum thiocyanate-2-acetylpyridinethiosemicarbazone complex into chloroform from hydrochloric acid. The complex has an absorption maximum at 470 nm with a molar absorptivity of 1.7 × 10⁴ liters mol^?1 cm^?1. Beer's law is valid from 0.1 to 6.5 ppm of molybdenum. The equilibrium shift method indicated a 1:4:2 complex. The method has been used successfully for the determination of molybdenum in molybdenum steels.     

Statistical optimisation applied to the spectrophotometric study of the tolmetin-Fe(III) complex

Tolmetin sodium has been examined and determined from dosage forms as its Fe(III) complex and the method has been optimized by statistical optimization.     

Alizarin-s,a reagent for thorium. a gravimetric,colorimetric, and spectrophotometric study

The claim of Beck in the use of alizarin-S for separating cerite earths from thorium could not be substantiated. Detailed conditions for estimating from 0.0095 to 6.3 mg of thorium dioxide in 50 ml of solution by the method of Rao and Murthy are described. The absorption characteristics of alizarin-S and its-thorium complex have been studied in their dependance on pH. The thorium complex has been shown by adopting different optical methods to correspond to Th-Al-S (a stoichiometric ratio of 1:1) which is also confirmed from gravimetric analyses. The dissociation coefficient of the complex at pH 2.7 has been computed to be less than 1.10^-8.     

Analytical applications of xylenol orange—VI A spectrophotometric study of the niobium-xylenol orange complex

The red niobium-Xylenol Orange complex has been studied spectrophotometrically. It offers a sensitive and selective reaction for the determination of traces of niobium. The coloured complex formed at pH 2·4 to 2·8 by heating in the presence of tartrate has a molar absorptivity of 16,000 and a formation constant of 5 × 10⁶ under the conditions studied. Most metals, including tantalum, vanadium and tungsten, do not interfere when zinc-EDTA complex and tartrate are used as masking agents. Nitrite, oxalate, pyrophosphate, and phosphate interfere. Fluoride can be demasked by addition of beryllium. Platinum gives a dark purple colour which also interferes.     

Analytical applications of xylenol orange—V A spectrophotometric study of the bismuth-xylenol orange complex

The red bismuth-Xylenol Orange complex has been studied spectrophotometrically. It offers a sensitive and selective reaction for determining traces of bismuth. The complex has an absorption maximum at 540 to 545 mμ, and requires a rather narrow acidity range (0.08 to 0.15N) for maximum colour development. It is a 1:1 complex and has a formation constant of 2.8 × 10⁵ under the conditions studied. Chloride masks the complex.     

Flow injection spectrophotometric determination of N-acetyl-L-cysteine as a complex with palladium(II)

We describe a new method using flow-injection analysis with spectro-photometric detection, suitable for the determination of N-acetyl-L-cysteine (NAC). The proposed method is appropriate for the determination of NAC in reaction with Pd(2+) ions in the concentration range from 1.0 × 10(-5) mol L(-1) to 6.0 × 10(-5) mol L(-1). The detection limit NAC was 5.84 × 10(-6) mol L(-1) and the recorded relative standard deviation of the method is in the range from 1.67 to 4.11%. NAC and Pd(2+) form complexes of Pd(2+):NAC molar ratios of 1:1 and 1:2, depending on the ratio of their analytical concentrations. The cumulative conditional stability constant for the Pd(NAC)(2)(2+) complex is β(12)' = 2.69 × 10(9) L(2) mol(-2). The proposed method was compared with the classic spectrophotometric determination of NAC, using the same reagent, PdCl(2), and had shown certain advantages: a) shorter analysis time; b) the use of smaller volumes of sample and reagents, which make the proposed method cheaper and faster for NAC determination in real samples without sample pretreatment.     

Desk-computer program for evaluation of complex equilibria from spectrophotometric data

The program MINISPEF is designed to run on a desk-computer with 16 kbytes of memory. It can calculate the optimum values of the overall stability constants and molar absorptivities of a maximum of 8 species with compositions M_qL_pH_r (r or q can be zero), or the mixed-ligand complexes formed in the system MA_N + MB_N (N = 2, 3 or 4), from spectrophotometric data. The program is based on the authors' program MINIPOT.     

Extraction and spectrophotometric determination of vanadium as a mixed ligand complex of oxine and azide

Summary Vanadium, oxine and azide react at pH 3.5–4.5 to give a dark green solid which extracts into benzene giving dark green solution. The extract has absorption maxima at 415 nm and 620 nm with molar absorptivities 8650 and 6040 respectively. Spectrophotometric investigations reveal that the extracting species has V, HOx and N₃ ^– in the ratio 122. Beer's law is obeyed upto 8.10g and 10.50g of vanadium per ml at 415 nm and 620 nm respectively. The formation constant and the free energy of formation are 8.5 ± 0.2×10⁶ and –9.61±0.30 Cal respectively at 30°. The interference of various foreign ions are studied and methods are proposed for the elimination of the interference of some of those substances. Infrared and magnetic data of the solid complex are given.

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Zusammenfassung Vanadin, Oxin und Azid reagieren bei pH 3,5–4,5 zu einem dunkelgrünen Feststoff, der sich mit Benzol als dunkelgrüne Lösung extrahieren läßt. Deren Absorptionsmaxima liegen bei 415 und 620 nm mit den molaren Extinktionen von 8650 bzw. 6040. Spektrophotometrisch ergibt sich das Verhältnis V:HOx: N₃ ^–=122. Bis 8,10 bzw. 10,5g V hat das Beersche Gesetz Gültigkeit. Die Komplexkonstante beträgt 8,5 ± 0,2×10⁶, die Bildungswärme –9,61±0,3 Kcal bei 30° C. Die Störung durch verschiedene Fremdionen wurde geprüft und in einigen Fällen beseitigt. IR- und magnetische Daten für die feste Komplexverbindung werden angegeben.

     

Chemometrics-assisted spectrophotometric method for simultaneous determination of vitamins in complex mixtures

An advanced independent component analysis algorithm (MILCA) is applied for simultaneous chemometric determination of fat- and water-soluble vitamins in complex mixtures. The analysis is based on the decomposition of spectra of multicomponent mixtures in the UV region. The key features of the proposed method are simplicity, accuracy, and reliability. Comparisons between the new algorithm and other established methods (MCR-ALS, SIMPLISMA, other ICA techniques) were made. Our results indicate that in most cases, MILCA is comparable or even outperforms other chemometrics methods taken for comparisons. The influence of different factors (abundance of components, noise, step of spectral scan, and scan speed) on decomposition performance has been investigated. The optimal conditions for spectroscopic registration have been identified. The proposed method was used for analysis of model mixtures and real objects (multivitamin drugs, food additives, and energy drinks). The resolved concentrations match well with the declared amounts and the results of reference methods.