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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
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vol. 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.
2
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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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vol. 10
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issue 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).
3
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Protonation acidity constants for benzotoluidides in sulfuric acid solutions

100%
Stojković G., Anastasova F.
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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.
4
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A new reagent system for the highly sensitive spectrophotometric determination of selenium

100%
Revanasiddappa H., Dayananda B.
Open Chemistry
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2006
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vol. 4
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issue 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.
5
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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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vol. 4
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issue 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.
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Quantitative determination of hexavalent chromium in aqueous solutions by UV-Vis spectrophotometer

88%
Fournier-Salaün M.-C., Salaün P.
Open Chemistry
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2007
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vol. 5
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issue 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. [...]
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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
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2018
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vol. 75
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issue 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.
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Indirect spectrophotometric determination of diltiazem hydrochloride in pure form and pharmaceutical formulations

75%
El-Didamony A.
Open Chemistry
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2005
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vol. 3
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issue 3
520-536
EN
Three simple, accurate, and sensitive spectrophotometric methods (A, B and C) have been described for the indirect assay of diltiazem hydrochloride (DIL.HCl), either in pure form or in pharmaceutical formulations. The first method (A) is based on the oxidation of DIL.HCl by N-bromosuccinimide (NBS) and determination of unconsumed NBS by measuring the decrease in absorbance of amaranth dye (AM) at a suitable λmax=521 nm. Other methods (B) and (C) involve the addition of excess cerric ammonium sulfate (CAS) and subsequent determination of the unconsumed oxidant by a decrease in the red color of chromotrope 2R (C2R) at a suitable λmax=528 nm or a decrease in the orange-pink color of rhodamine 6G (Rh6G) at λmax=525 nm, respectively. Regression analysis of Beer-Lambert plots showed good correlation in the concentration ranges 3.0–9.0, 3.5–7.0 and 3.5–6.3 μg ml−1 for methods A, B and C, respectively. The apparent molar absorptivity, Sandell's sensitivity, detection and quantification limits were calculated. The proposed methods have been applied successfully for the analysis of the drug in its pure form and its dosage form. No interference was observed from a common pharmaceutical adjuvant. Statistical comparison of the results with the reference method shows excellent agreement and indicates no significant difference in accuracy and precision.
9
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Comparison of Five Svd-Based Algorithms for Calibration of Spectrophotometric Analyzers

75%
Wagner J., Morawski R. Z., Miękina A.
Metrology and Measurement Systems
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2014
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issue 2
10
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New spectrophotometric methods for the determination of nifedipine in pharmaceutical formulations

75%
Rahman N., Azmi S. N. H.
Acta Biochimica Polonica
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2005
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vol. 52
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issue 4
915-922
EN
Two simple, sensitive and economical spectrophotometric methods were developed for the determination of nifedipine in pharmaceutical formulations. Method A is based on the reaction of the nitro group of the drug with potassium hydroxide in dimethyl sulphoxide (DMSO) medium to form a coloured product, which absorbs maximally at 430 nm. Method B uses oxidation of the drug with ammonium molybdate and subsequently reduced molybdenum blue is measured at 830 nm. Beer's law is obeyed in the concentration range of 5.0-50.0 and 2.5-45.0 µg ml-1 with methods A and B, respectively. Both methods have been successfully applied for the assay of the drug in pharmaceutical formulations. No interference was observed from common pharmaceutical adjuvants. The reliability and the performance of the proposed methods are established by point and interval hypothesis tests and through recovery studies.
11
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Reactions of Pseudomonas aeruginosa pyocyanin with reduced glutathione

63%
Cheluvappa R., Shimmon R., Dawson M., Hilmer S. N., Le Couteur D. G.
Acta Biochimica Polonica
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2008
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vol. 55
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issue 3
571-580
EN
Pseudomonas aeruginosa is the most common cause of chronic and recurrent lung infections in patients with cystic fibrosis (CF) whose sputa contain copious quantities of P. aeruginosa toxin, pyocyanin. Pyocyanin triggers tissue damage mainly by its redox cycling and induction of reactive oxygen species (ROS). The reactions between reduced glutathione (GSH) and pyocyanin were observed using absorption spectra from spectrophotometry and the reaction products analysed by nuclear magnetic resonance imaging. Pyocyanin reacted with GSH non-enzymatically at 37°C resulting in the production of red-brown products, spectophotometrically visible as a 480 nm maximum absorption peak after 24 h of incubation. The reaction was concentration-dependent on reduced glutathione but not on pyocyanin. Minimizing the accessibility of oxygen to the reaction decreased its rate. The anti-oxidant enzyme catalase circumvented the reaction. Proton-NMR analysis demonstrated the persistence of the original aromatic ring and the methyl-group of pyocyanin in the red-brown products. Anti-oxidant agents having thiol groups produced similar spectophotometrically visible peaks. The presence of a previously unidentified non-enzymatic GSH-dependent metabolic pathway for pyocyanin has thus been identified. The reaction between pyocyanin and GSH is concentration-, time-, and O2-dependent. The formation of H2O2 as an intermediate and the thiol group in GSH seem to be important in this reaction.
12
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Statistical Calibration of Model Solution of Analytes

63%
Simeonov D., Spasov L., Simeonova P.
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vol. 19
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issue 1
67-75
EN
A new method based on spectrophotometric-partial least-squares procedure was proposed for simultaneously determination of thorium and zirconium using SPADNS (4,5-Dihydroxy-3-(p-sulfophenylazo)-2,7-naphthalene disulfonic acid, trisodium salt) as a color reagent. Absorbance measurements were made in the range of γ = 541÷620 nm with 1.0 nm steps in buffered solutions at pH 3.5. The linear ranges were obtained for 0.5÷11.5 and 1.5÷14.5 μg cm-3 for Th4+ and Zr4+ ions, respectively. The limits of detection were determined 0.4 and 1.2 μg cm-3 for thorium and zirconium, respectively. The standard deviation (n = 3) and recovery percent of 10 samples in the prediction set were obtained in the amplitude 0.22÷0.38 μg cm-3 and 91.3÷109.2, respectively. The proposed method was used for simultaneously determination of mentioned ions in spiked real water samples and wastewater. The results show that the method is applicable for the analysis of samples with similar matrix.
PL
Nowa metoda opiera się na procedurze spektrofotometrycznej - najmniejszych kwadratów, która została zaproponowana do równoczesnego oznaczania toru i cyrkonu z wykorzystaniem SPADNS (kwas 4,5-Dihydroksy-3-(p-sulfofenylazo)-2,7-naftaleno disulfonowy, sól trisodowa) jako odczynnika koloru. Pomiarów absorbancji dokonano w zakresie λ = 541÷620 nm co 1,0 nm w roztworach buforowych o pH 3,5. Liniowy zakres uzyskano przy stężeniach jonów Th4+ i Zr4+ odpowiednio 0,5÷11,5 i 1,5÷14,5 μg cm-3. Granice wykrywalności dla toru i cyrkonu wynosiły odpowiednio 0,4 i 1,2 μg cm-3. Wyznaczono odchylenie standardowe (n = 3) i procent odzysku w serii 10 próbek odpowiednio w zakresie 0,22÷0,38 i 91,3÷109,2 μg cm-3. Proponowana metoda została zastosowana do równoczesnego oznaczania wymienionych jonów w wzbogaconych próbkach rzeczywistych wody i ścieków. Wyniki pokazują, że ta metoda może być wykorzystywana do analizy próbek o podobnej matrycy.
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