Wyniki wyszukiwania - Biblioteka Nauki

1

Competitive Spectrophotometrc Study of Complexation of Dibenzopyridino-18-crown-6 with Ca2+, Sr2+, and Ba2+ in Binary Dimethylsulphoxide-Acetonitrile Solutions

100%

Zolgharnein J. , Zahirredini F. , Azimi G.

Polish Journal of Chemistry

|

2003

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tom Vol. 77 / nr 7

813-820

EN

The complexation of dibenzopyridino-18-crown-6 (DBPY18C6) with Ca2+, Sr2+ and Ba2+ has been studied in binary dimethylsulphoxide - acetonitrile mixtures at 25_C by a competitive spectrophotometric technique, using murexide as a metal ion indicator. Stoichiometry and stability of the resulting complexes were evaluated by KINFIT program. The stability of 1:1 complexes prepared were found strongly solvent dependent. There is an inverse linear relationship between log Kf and mole fraction of dimethylsulphoxide (DMSO) in the solvent. In all these solvents the increase of %AN increases the stability of DBPY18C6 complexes with alkaline earth cations in the sequence Ba2+ > Sr2+ > Ca2+.

2

Wykorzystanie spektrofotometrii w podczerwieni do oznaczania aminowego inhibitora utleniania w olejach turbinowych uszlachetnionych

100%

Pinko J.

Energetyka

|

2008

|

tom nr 10

708-712

PL

Omówiono proces utleniania olejów oraz mechanizm działania alkilowanych diaryloamin jako inhibitora. Przedstawiono wybrane rezultaty przeprowadzonych badań laboratoryjnych, z wykorzystaniem spektrofotometru FTIR - JASCO, nad sposobem oznaczania tego typu inhibitora. Badania pozwoliły na opracowanie metody określania procentowej zawartości pakietu dodatków na podstawie obecnej w pakiecie aminy.

EN

Discussed is the process of oil oxidation as well as the functioning mechanism of alkylated diaryloamins as an inhibitor. Presented are results of selected laboratory tests concerning methods of determination the inhibitor of that type with the use of FTIR-JASCO spectrophotometer. The research enabled to elaborate a method to determine the percentage content of additives in a packet on the basis of amine present in such a packet.

3

A GREEN METHOD FOR THE REMOVAL OF ZINC(II) IONS FROM WASTEWATER USING MODIFED BIOPOLYMERS

100%

Jeyaseelan C. , Jain A. , Jugade R.

Progress on Chemistry and Application of Chitin and its Derivatives

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2021

|

tom 26

101-111

EN

Zinc pollution in wastewater is a global problem because it is highly toxic. Zinc is commonly used in industries that transfer the water containing zinc directly into water sources, leading to pollution. Exposure to a high level of zinc causes major health problems. This study evaluated the adsorption of zinc ions from aqueous system using modified biopolymers of chitosan by crosslinking with sulphates using the batch adsorption method; the concentration was determined using atomic absorption spectrophotometry. The sulphate cross-linked chitosan (SCC) was characterised by several method. The effects of various experimental parameters such as pH, contact time, concentration, adsorbent dosage and temperature were investigated. Under the optimised conditions, the percentage efficiency for the removal of zinc(II) was up to 85%. Freundlich and Langmuir isotherms were used to analyse the equilibrium adsorption data along with kinetic studies. Various thermodynamic parameters have also been reported.

4

Evaluation of dual wavelength ß-correction spectrophotometry

100%

Kobyłecka J. , Cygański A.

Chemia Analityczna

|

1999

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tom Vol. 44, No. 3B

567-575

EN

The principle of the new duaI wavelength B-correction spectrophotometric method recommended by its author, H.W. Gao in cases of high reagent bIank absorbance, ha been discussed. Doubts have been expressed about alfa-correction which occurs in the formulae and the method of its deteImination. The method has been used to examine spectrophotometric methods of determination of Mg(II) with eriochrome black T, Ca(II with murexide, AI(III) with eriochrome cyanine R, Cu(II) and Co(III) with pyridylazoresorcinolcinol. The purpose of the examination was to compare the results of detelrinations obtained by classical spectrophotometric method and B-correction method. It has beer confirmed that the application of B-correction alone increases the sensitivity and improves the precision and the accuracy of the methods in which reagent blank absorbency is high. It has been demonstrated that it is impossible to determine the correct alfa -correction value, and the application of the correction determined according to the 14ecommendations of' the authol4 of the method may lead to serious errors in the results.

PL

Omówiono zasadę nowej metody spektrofotometrii z B-korekcją przy dwu długościach fali, która jest polecana przez jej autora H. W. Gao w przypadku wysokiej absol4bancji ślepej próby. Zwrócono uwagę na wątpliwości jakie budzi występujący we wzorach współczynnik korekcyjny a i sposób jego wyznaczania. Metodę tę zastosowano do zbadania spektrofotometrycznych metod oznaczania Mg(II) z czernią eriochromową T, Ca(II) z mureksydem, AI(III) z eriochromocyjaniną R, Cu (II) i Co(III) z pirydyloazorezorcynolem. Badania miały na celu porównanie wyników oznaczeń uzyskiwanych klasyczną metodą spektrofotometryczną i metodą B-korekcji. Potwierdzono, że zastosowanie tylko B-kolekcji podwyższa czułość, poprawia precyzję i dokładność metod, w których absorbancja ślepej próby jest wysoka. Wykazano, że otrzymanie prawidłowej wartości współczynnika kol.ekcyjnego a nie .jest możliwe, a zastosowanie tego współ-czynnika wyznaczonego według wskazówek autora metody może powadzić do otrzymania wyników obarczonych bardzo dużymi błędami.

5

Determination of the Dexlansoprazole in Bulk and Spiked Human Plasma by Extraction Spectrophotometry

100%

Sekharan C. B. , Rao M. P. , Mahesh M. , Chandramouli I. , Seemanth J.

International Letters of Chemistry, Physics and Astronomy

|

2015

|

tom Vol. 52

28--38

EN

This paper describes a simple extraction spectrophotometric method for the quantification of dexlansoprazole in bulk and spiked human plasma. This method involves formation of stable yellow colored chloroform extractable ion-pair complex of the amino derivative of dexlansoprazole with acid dye, namely methyl orange in acidic medium. The ion-pair complexes exhibit absorption maxima at 425 nm. Dexlansoprazole can be determined up to 4-40 μg/mL by the proposed method. The effect of optimum reagent concentration was studied. The relative standard deviations (≤1. 246%) obtained in the intra-day and inter-day analyses were found to be satisfactory. The accuracy results exhibited the mean recovery and percentage error in the range of 99.137%–100.574% and 0.012%–0.863%. When applied for the assay of the dexlansoprazole in spiked human plasma sample, recovery mean values ranged from 96.495–98.960%. The proposed method is useful for the estimation of the dexlansoprazole in bulk and human plasma samples.

6

Determination of cholic acid in bile and pharmaceutical preparation

100%

Kurzawa M. , Koter I. , Szłyk E.

Chemia Analityczna

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2006

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tom Vol. 51, No. 3

411-418

EN

New analytical procedures for determination of cholic acid in powdered and liquid bile samples and in Tympachol, pharmaceutical preparation derived from bile have been developed. Spectrophotometric methods are based on the reaction between cholic acid and aldehydes (5-methyl furfural, 5-methyl-2-tiophene and ortophtalic) in sulfuric acid solution. Molar absorptivity coefficients for the obtained species ranged from 1.38 x 104 to 6.94 x l04 L mol-1 L mol-1and correlation coefficient exceeded 0.9984. The RSD values for the developed procedures were not higher than 2.85% for the powdered bile sample. 3.31% for the liquid bile sample, and 3.48% for Tympachol. Accuracy and precision were investigated applying the Student-t and F-Snedecor tests and the results were compared to those obtained by Polish Standard and HPLC methods.

PL

W pracy opisano nowe analityczne procedury do oznaczania kwasu cholowego w żółci sproszkowanej, piynnej oraz w Tympacholu - preparacie farmaceutycznym na bazie żółci. Metody spektro foto metryczne zostały oparte na reakcji pomiędzy kwasem cholowym a aldehydami: 5-metylofurfuraIem, 5-metylo-2-liofenowym oraz ortoftalowym w środowisku kwasu siarkowego. Molowe współczynniki absorpcji dla otrzymanych związków wynosiły od 1,38 x 104 do 6,94 x 104 L mol-1 L mol-1, a współczynniki korelacji przekraczały 0,9984. Wartości RSD dla wszystkich opracowanych procedur w przypadku żółci sproszkowanej były niższe niż 2,85%, w przypadku żółci płynnej niższe niż 3,31%, natomiast w przypadku preparatu nie przekraczały 3,48%. Dokładność i precyzję opracowanych metod porównano z wynikami uzyskanymi metodą opisaną w Polskich Normach oraz z wynikami uzyskanymi metodą HPLC, stosując tesly t-Studenta i F-Snedecora.

7

Simple photometric determination of free cyanide ion in aqueous solution with 2,6-dichlorophenolindophenol

100%

Yari A. , Kargosha K.

Open Chemistry

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2006

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tom 4

|

nr 2

329-337

EN

In this work, a simple photometric method with high accuracy and precision for measuring trace amounts of free cyanide ion in aqueous solution is demonstrated. Under the evaluated conditions, we could determine CN− concentration in the range of 5–70 ppm easily. The work is based upon the photometric titration of CN− with Co(II) in the presence of 2,6-dichlorophenolindophenol (DCPIP) at λmax = 602 nm in aqueous solution. The optimal conditions, such as pH, ionic strength, and concentration of chromopher were evaluated. The interence effect of many other cations and anions studied and the results are given here. The optimized titration was successfully used to determine the concentration of free cyanide ion in aqueous solutions.

8

A new reagent system for the highly sensitive spectrophotometric determination of selenium

100%

Revanasiddappa H. , Dayananda B.

Open Chemistry

|

2006

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tom 4

|

nr 4

592-603

EN

Highly sensitive and simple spectrophotometric determination of selenium is described for the determination of selenium(IV) using a new reagent leuco malachite green. The method is based on the reaction of selenium(IV) with potassium iodide in an acidic condition to liberate iodine, the liberated iodine oxidizes leuco malachite green to malachite green dye. The green coloration was developed in an acetate buffer (pH 4.2–4.9) on heating in a water bath (∼ 40 °C). The formed dye exhibits an absorption maximum at 615 nm. The method obeys Beer’s law over a concentration range of 0.04–0.4 µg mL−1 selenium. The molar absorptivity and Sandell’s sensitivity of the color system were found to be 1.67 × 105 L mol−1 cm-1 and 0.5 ng cm−2, respectively. The optimum reaction conditions and other analytical parameters have been evaluated. The proposed procedure has been successfully applied to the determination of selenium in real samples of water, soil, plant material, human hair, and cosmetic samples. The results were compared to those obtained with the reference method. Statistical analysis of the results confirms the precision and accuracy of the proposed method. In addition, the developed method is cost-effective and involves easily accessible instrumentation technique which can be used by ordinary research laboratories.

9

2-(4-Diethylaminostyryl)-1,3,3-trimethyl-5-thiocyanato-3H-indolium chloride as a new reagent for indirect spectrophotometric red-ox determination of Osmium (VI)

100%

Kormosh Z. , Korolchuk S.

Polish Journal of Chemical Technology

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2008

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tom 10

|

nr 2

17-19

EN

A highly sensitive indirect spectrophotometric redox method for the determination of osmium is reported on. The method is based on the oxidation of iodide by osmium (VI) and the spectrophotometric detection of the liberated iodine in the form of complex anion associate with 2-(4-diethylaminostyryl)-1,3,3-trimethyl-5-thiocyanato-3H-indolium chloride reagent. The appropriate reaction conditions have been established. The molar absorptivity is (0.2-1.2)·105 dm3/mol·cm at 589.5 nm wavelength. The absorbance of the coloured extracts obeys the Beer's law in the range to 7.6 mg/dm3 of Os(VI).

10

Study of Complex Formation between Iodoquinol (IQ) and Co2,+ Mn2+, Cd2+, Pb2+ and Zn2+ Cations in DMF/EtOH Bi nary Solvent Mixtures Us ing Spectrophotometry

100%

Nezhadali A. , Hosseini H. A. , Langara P.

Polish Journal of Chemistry

|

2009

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tom Vol. 83, nr 4

573-580

EN

The complexation reactions between iodoquinol and Co2+, Mn2+, Cd2+, Pb2+ and Zn2+ cations were studied in different DMF/EtOH binary mixtures at the ionic strength of 0.1 M sodium nitrate. The spectrophotometric method was used for the determination of stability constants and stoichiometries of complexes. Job’s and moleratio methods evidenced a 1:1 stoichiometry in all of the cases. It was found that the stability constants of the complex formed between the ligand (IQ) and the cations in all cases in crease with in creasing of EtOH per cent in binary mixtures. In the most cases the maximum formation constant for Zn2+–IQ complex was found.

11

Zastosowanie spektrofotometrii uv-vis do oznaczenia rozpuszczalności chlorowodorku bupiwakainy

100%

Sykuła-Zając A. , Zdziarska P.

Zeszyty Naukowe. Chemia Spożywcza i Biotechnologia / Politechnika Łódzka

|

2009

|

tom Z. 73

43-59

PL

W celu wstępnego zbadania rozpuszczalności i ogólnego zachowania się chlorowodorku bupiwakainy, leku znieczulającego miejscowo, w różnych rozpuszczalnikach oraz w środowiskach o różnym pH i przy zmiennych stężeniach wykorzystano spektroskopię UV-Vis. W literaturze światowej, jak i polskiej znajduje się niewiele informacji dotyczących tego typu badań, dlatego też wyniki uzyskane w tej pracy stanowią pewne uzupełnienie stanu wiedzy w tym zakresie.

EN

Preliminary examination of solubility and general behaviour of bupivacaine hydrochloride, local anaesthetic, in different solvents, pH environment and variable concentrations was performed using UV-Vis spectrophotometry. There are not much information, including this kind of examinations, in world and Polish literature. Therefore, obtained results in this paper present certain addition in knowledge in this area.

12

Protonation acidity constants for benzotoluidides in sulfuric acid solutions

100%

Stojković G. , Anastasova F.

Open Chemistry

|

2006

|

tom 4

|

nr 1

56-67

EN

The protonation of o-, m-and p-benzotoluidide in sulfuric acid solutions is studied by UV spectroscopy in the 190–350 nm region. Principal component analysis is applied to estimate the contributions of the effect of protonation and the medium effect. For the substances studied in this work, the first principal component (PC) captures about 98 % of the variance and the second PC ∼100 % of the cumulative percentage variance in the 210–350 nm region. The same spectral region is used for calculation of the ionization ratio from the coefficients of the first PC and mole fractions of the base and its conjugate acid. Using these data and Hammett's equation (pK BH + = H X + log I), the pK BH + values for the protonation reaction are obtained. The dissociation constants as well as the solvent parameters m* (∼0.43) and ϕ (∼0.60) are calculated using the Excess Acidity Method (-pK BH += 2.28–2.30) and the Bunnett-Olsen Method (-pK BH += 2.24–2.28). The probable sites of protonation are discussed.

13

The effect of molding conditions on the quality of geopolymer surfaces

100%

Jaglarz J. , Wyszyński D. , Lach M. , Mikuła J. , Duraj R.

Optica Applicata

|

2020

|

tom Vol. 50, nr 1

135--146

EN

The presented work describes the method of measuring surface topography with application of BRDF (bidirectional reflectance distribution function), ellipsometry and spectrophotometry. This non-contact method enables measurement and analysis of large area surfaces, such as plasters and facades. A standard method of topography analysis does not describe sufficiently all of the interesting features. The visual aspect of the surface evaluation is very important from the functional and utilitarian point of view. The proposed methods of surface analysis enable not only the quantitative evaluation but also indirectly the qualitative properties (visual aspects).

14

Spectrophotometric Study of the Interaction of Iodine Monochloride with Aza-15-crown-5 in Chloroform Solution

100%

Semnani A. , Pouretedal H. , Keshavarz M. , Firooz A.

Polish Journal of Chemistry

|

2006

|

tom Vol. 80, nr 12

2055-2062

EN

The complex formation between iodine monochloride and aza-15-crown-5 (A15C5) has been studied spectrophotometrically in chloroform solution at 25 graduate C. The results prove the formation of 2:3 and 3:4 stoichiometries between A15C5:ICl. In the case of 2:3 reaction, the simultaneous formation of ICl2 and I2 through two chemical equilibria is confirmed. The 3:4 reaction proceeds via consumption of I2 and formation of I3 . Several equations are suggested for the observations. The stability constants of 2:3 and 3:4 adducts were calculated by computer fitting of the absorbance-mole ratio data. The experiments were repeated at 40C and results compared with those obtained at 25C. The results indicate that the complexes are weaker at the higher temperature. The conductivity measurements are indicative of ion pairing in all cases. Finally, the solid 3:4 adduct was isolated and its IR spectrum compared with that of A15C5.

15

Sonochemical Degradation of Some Triphenyl Methane Dyes

100%

Panwar C. , Kumar A. , Paliwal M. , Punjabi P. B. , Ameta S. C.

Polish Journal of Chemistry

|

2007

|

tom Vol. 81, nr 10

1777-1784

EN

Sonochemical degradation of brilliant green and malachite green has been carried out by ultrasound (4 MHz) in an ultrasonic interferometer. The sonochemical degradation of dyes was observed by spectrophotometric method. The effect of various parameters like pH, concentration of dyes, solvent composition, temperature, nature and concentration of surfactant on the reaction rate of the sonochemical degradation was also observed. The value of energy of activation was also computed for sonochemical degradation. A tentative mechanism has been proposed.

16

Spectrophotometric study of thermodynamics and kinetics of charge-transfer complexation of dibenzopyridino-18-crown-6 with iodine in chloroform solution

88%

Zolgharnein J. , Shamsipur M.

Polish Journal of Chemistry

|

1998

|

tom Vol. 72, nr 11

2486-2492

EN

The charge-transfer complexation reaction between iodine and dibenzopridino-18-crown-6 (DBPY18C6) has been investigated spectrophotomertically in chloroform solution at different temperatures. The resulting comlex was formulated as (DBPY18C6...I(+))I(-/3).The enthalpy and entropy of the complex formation were evaluated from the temperature dependence of the formation constant. The resulting charge-transfer complex is both enthalpy and entropy stabilized. The rate constants at various temperatures and the activation parameters were evaluated.

17

DETERMINATION OF FLUOXETINE HYDROCHLORIDE VIA ION PAIR COMPLEXATION WITH ALIZARIN RED S

88%

Clementina C. I. , Alexandra N. F. , Valentina U.

Acta Poloniae Pharmaceutica - Drug Research

|

2018

|

tom 75

|

nr 6

1293-1303

EN

Two UV-Vis spectrophotometric methods and one fluorimetric method have been developed for the quantitative determination of fluoxetine hydrochloride in bulk and pharmaceutical formulations. These methods are based on the ion pair complex formation between alizarin red S and fluoxetine hydrochloride. In the first method (method A), the yellow-coloured complex obtained in acidic medium was extracted with chloroform, and the absorbance of chloroformic solution was measured at 425 nm. Beer’s law limits (9.5 – 48 µg/mL), the molar absorptivity (5256 L · mol-1· cm-1), and the complex composition (1:1) were determined. In the second method (method B), the yellow complex fluoxetine – alizarin red S extracted in chloroform was broken in alkaline medium, and the absorbance of the resulting violet-coloured free dye was measured at 524 nm. A linear relationship was observed in the range 9.0 – 54 µg/mL. In the third method (method C) the fluorescence intensity of the fluoxetine – alizarin red S complex, obtained in the same manner as for method A, was measured at 594 nm after excitation at 425 nm. The fluorescence intensity was proportional to the drug concentration in the linear range of 2.7-10.2 µg/mL. The limits of detection and quantification have also been calculated. Furthermore, the proposed methods have been successfully applied for the assay of the drug in pharmaceutical dosage forms.

18

Quantitative determination of hexavalent chromium in aqueous solutions by UV-Vis spectrophotometer

88%

Fournier-Salaün M.-C. , Salaün P.

Open Chemistry

|

2007

|

tom 5

|

nr 4

1084-1093

EN

In the last decade, different methods have been developed for the determination of chromium(VI) concentration in water. These methods use high cost equipment or they require a long preparation time. Because of their drawbacks, this paper describes an on-line, rapid and sensitive procedure for the determination of Cr(VI) concentrations in aqueous solutions via pH and absorption measurements. Only four Cr(VI) species are considered. The effects of pH and of total amount of chromium on the Cr(VI) speciation are investigated. The molar absorptivities of four chromium species at 371 nm are determined by minimising an objective function. The knowledge of these molar absorptivities and the measurements of pH and absorption at 371 nm lead to a rapid determination of total Cr(VI) concentration. The reliability and applicability of the method were confirmed using synthetic water samples. [...]

19

Study of the Stability of Some Ion-Pairs in Non-Aqueous Solutions by Potentiometric and Spectrophotometric Methods

88%

Gorodkiewicz E.

Polish Journal of Chemistry

|

2001

|

tom Vol. 75, nr 1

127-133

EN

Changes in selected complexes caused by photodissociation were studied potentiometrically by measuring the time dependence of electromotive force of suitable cells and spectrophotometrically by measuring the time dependence of absorbance to evaluate the stability constants. Ion pairs labetalol (LAB)-reineckate (REINE) in nitromethane and crystal violet (CV)-tetrachloroferrate(III) (FeCl4) in tetrachloroethane were used. The concentration ranges were determined, in which the EMF variations are greatest: the 4-5.5 × 10-4 mol l-1 range for the LAB-REINE complex and the 0.9-3 × 10-6 for the CV-FeCl4 complex. Linear dependence of the EMF variation on the intensity of radiation, as well as a slight effect of temperature on irradiated solution were found. The stability constants of the studied complexes in chloroform, determined directly from spectrophotometric measurements are log Beta av = 6.6 for LAB-REINE complex and log av = 7.3 for the CV-FeCl4 complex.

20

Measurement data processing in spectrophotometric analysers of food. Review paper

88%

Morawski R. Z.

Metrology and Measurement Systems

|

2012

|

tom Vol. 19, nr 4

623-652

EN

Spectrometry, especially spectrophotometry, is getting more and more often the method of choice not only in laboratory analysis of (bio)chemical substances, but also in the off-laboratory identification and testing of physical properties of various products, in particular - of various organic mixtures including food products and ingredients. Specialised spectrophotometers, called spectrophotometric analysers, are designed for such applications. This paper is on the state of the art in the domain of data processing in spectrophotometric analysers of food (including beverages). The following issues are covered: methodological background of food analysis, physical and metrological principles of spectrophotometry, the role of measurement data processing in spectrophotometry. General considerations are illustrated with examples, predominantly related to wine and olive oil analysis.