Comparison of spectrophotometric methods of determination of zinc(II) in biological material and study of its complex formation reactions with 4-(2-pyridylazo)resorcinol

1979 ◽  
Vol 44 (3) ◽  
pp. 725-741 ◽  
Author(s):  
Miloš Pollák ◽  
Vlastimil Kubáň
Keyword(s):  
Complex Formation ◽  
Stability Constants ◽  
Biological Material ◽  
Complex Species ◽  
Fundamental Parameters ◽  
Methods Of Determination ◽  
Spectrophotometric Methods

The methods of determination of Zn(II) with dithizone, zincone, PAN, and PAR were compared by considering the fundamental parameters of the photometric methods. The compositions, values of the molar absorptivities, and values of the equilibrium and stability constants of the complex species MLH, ML, ML2H2, ML2H, and ML2 of zinc(II) with PAR were determined graphically by means of the slope-intercept transformations, and numerically from the absorbance-pH curves and from the absorbance dependences on the component concentrations by employing the program PRCEK T200 and from the continual variations curves by using the program JOBCON.

The affinity of aldehydic compounds to complex formation. Nickel(II) and cobalt(II) complexes with 2-pyridinecarboxaldehyde

1977 ◽  
Vol 55 (14) ◽  
pp. 2613-2619 ◽  
Author(s):  
M. S. El-Ezaby ◽  
M. A. El-Dessouky ◽  
N. M. Shuaib
Keyword(s):  
Complex Formation ◽  
Aqueous Solutions ◽  
Stability Constants ◽  
Metal Ion ◽  
Experimental Conditions ◽  
Complex Species ◽  
Spectrophotometric Methods ◽  
Complex Equilibria ◽  
The Stability ◽  
Hydroxy Groups

The interactions of Ni(II) and Co(II) with 2-pyridinecarboxaldehyde have been investigated in aqueous solutions at μ = 0.10 M (KNO3) at 30 °C. The stability constants of different complex equilibria have been determined using potentiometric methods. Spectrophotometric methods were also used in the case of the nickel(II) – 2-pyridinecarboxaldehyde system. It was concluded that nickel(II) and cobalt(II), analogous to copper(II), enhance hyrdation of 2-pyridinecarboxaldehyde prior to deprotonation of one of the geminal hydroxy groups. Complex species of 1:1 as well as 1:2 metal ion to ligand composition exist under the experimental conditions used.

scholarly journals Determination of Iron in Raw Materials, During Fabric Processing, and in Wastewaters of the Textile Industry

1999 ◽  
Vol 82 (3) ◽  
pp. 683-688 ◽  
Author(s):  
Zorana Grabaric ◽  
Ljerka Bokic ◽  
Branka Stefanovic
Keyword(s):  
Stability Constants ◽  
Textile Industry ◽  
Raw Materials ◽  
Variation Method ◽  
Ratio Method ◽  
Industrial Water ◽  
Complex Species ◽  
Woolen Fabric ◽  
Good Agreement

Abstract The Schiff base 2-(2-pyridylmethyieneamino)phenol (PMAP) was investigated as a spectrophotometric reagent for determination of iron in caustic soda, cotton yarn and fabric, woolen fabric, and industrial water. The solution properties of Fe(III)-PMAP complexes were determined. At pH 4.4 and 5.6, Fe(III) forms stable complexes with PMAP, with molar absorption coefficients (ε) of 3.00 × 103 and 7.44 × 103/M.cm, respectively. Composition and cumulative stability constants were determined by the mole ratio method (MRM) and the mole fraction variation method (MFVM). At the lower pH (4.4), the predominant complex species in the solution obtained with both methods are ML2, with fairly good agreement of stability constants: log βML2 = 7.00 ± 0.04 with MRM and 7.31 ± 0.01 with MFVM. At the higher pH (5.6), the composition and stability constants of predominant complex species in the solution obtained with the 2 methods were not in good agreement, perhaps because of the coexistence of several species, such as Fe-PMAP, Fe-hydroxo, and Fe-acetate complexes. PMAP is a sensitive reagent for determination of Fe(III). The detection limit of 0.4 μg/mL is lower than those of other frequently used spectrophotometric reagents for Fe. The reagent is ecologically more acceptable, because extraction with organic solvents is avoided. All measurements were made at pH 5.6 because sensitivity was higher at this pH. The high Fe values obtained for industrial water (31.8 μg/mL) indicate that some modifications in the process have to be done. Concentration of Fe in wastewater was much lower (15.9 μg/mL). The results for cotton and woolen fabric indicate that accumulation of Fe in wool is much higher than in cotton (84.4 μg/mL and 29.3-53.1 μg/mL, respectively).

scholarly journals Simple Methods for the Spectrophotometric Determination of Carvedilol

2012 ◽  
Vol 2012 ◽  
pp. 1-6
Author(s):  
Divya N. Shetty ◽  
B. Narayana
Keyword(s):  
Charge Transfer ◽  
Complex Formation ◽  
Confidence Level ◽  
Charge Transfer Complex ◽  
Condensation Reaction ◽  
Pharmaceutical Preparations ◽  
Molar Absorptivity ◽  
Spectrophotometric Methods ◽  
Accuracy And Precision

Two simple spectrophotometric methods are described for the determination of carvedilol (CAR). Method A is the condensation reaction of CAR with p-dimethylaminobenzaldehyde (PDAB), and the reaction mixture exhibits maximum absorbance at 601 nm. Method B is based on the charge transfer complex formation of CAR with p-chloranil; the color developed is measured at 662 nm. The calibration graphs are found to be linear over 50.00–250.00 and 20.00–100.0 μg mL−1 with molar absorptivity values of 0.92×103 and 0.257×104 L mol−1cm−1 for CAR-PDAB and CAR-p-chloranil, respectively. Statistical comparisons of the results are performed with regard to accuracy and precision using Student’s t-test and F-test at 95% confidence level. The methods are successfully employed for the determination of CAR in pharmaceutical preparations, and the results agree favorably with the reference and proposed methods.

scholarly journals Spectrophotometric Methods for the Determination of the Antidepressant Drug Paroxetine Hydrochloride in Tablets

2005 ◽  
Vol 88 (2) ◽  
pp. 490-495 ◽  
Author(s):  
Armağan Önal ◽  
Evrim.Ş Kepekçi ◽  
Aysel Öztunç
Keyword(s):  
Antidepressant Drug ◽  
Coupling Reaction ◽  
Bromocresol Green ◽  
Bromophenol Blue ◽  
Complex Species ◽  
Spectrophotometric Methods ◽  
Beer's Law ◽  
Beer’S Law ◽  
Paroxetine Hydrochloride

Abstract Simple, sensitive, and accurate visible spectrophotometric methods are described for the determination of paroxetine hydrochloride (PA) in tablets. Among them, the first 3 methods are based on the ion-pair complexes of PA formed with bromothymol blue (BTB), bromophenol blue (BPB), and bromocresol green (BCG) in aqueous acidic buffers. The complex species extracted into chloroform were quantitatively measured at 414 nm with BTB and BCG and at 412 nm with BPB. Beer's law was obeyed over the concentration ranges of 2–20, 2–16, and 2–16 μg/mL, respectively. The fourth method described is based on a coupling reaction between PA and 7-chloro-4-nitrobenzofurazon (NBD-Cl) in borate buffer, pH 8.5, in which a yellow reaction product that was measured at 478 nm was formed. The Beer's law range for this method was 2–10 μg/mL. The last method developed describes the interaction of PA base, as an n-electron donor, with 7,7,8,8-tetracyanoquinodimethane (TCNQ), as a π-acceptor, in acetonitrile to give blue-colored TCNQ− radical anion with absorption maxima at 750 and 845 nm. Measured at 845 nm, the absorbance–concentration plot was rectilinear over the range of 1.5–15 μg/mL. The new methods developed were successfully applied to the determination of PA in tablets without any interference from common tablet excipients. The results of the methods were in good agreement with those obtained with an official liquid chromatographic method. This report describes first colorimetric methods for the determination of PA.

A spectrophotometric study of the complex formation between cobalt(III) and trans-1,2-cyclohexanedinitrilotetraacetic acid (CyDTA)

1979 ◽  
Vol 57 (17) ◽  
pp. 2292-2296 ◽  
Author(s):  
Rita K. Hessley ◽  
Shoba Waykole ◽  
Robert L. Sublett
Keyword(s):  
Complex Formation ◽  
Stability Constants ◽  
Spectrophotometric Study ◽  
Higher Order ◽  
Order Complex ◽  
Spectrophotometric Methods ◽  
Investigation Result ◽  
Unique System ◽  
The Stability

An intriguing and unique system has been observed during the otherwise routine study of the cobalt(III) complex of trans-1,2-cyclohexanedinitrilotetraacetic acid (CyDTA). Using classical spectrophotometric methods to determine the stoichiometry and the stability of a complex, significant deviations from the predicted 1:1 complex were observed in a system buffered at pH = 4.6. It is postulated that in addition to the usual 1:1 complex, the propensity of the reactants to form complexes and the strong oxidizing conditions used in this investigation result in the formation of a second, higher order complex between Co(III) and CyDTA. When the concentration of CyDTA exceeds that of Co(III), the metal:ligand ratio for this complex is 1:2. A structure is proposed, and approximate stability constants of both complexes are discussed.

scholarly journals Spectrophotometric Determination of Antidepressant Drug Duloxetine in Pharmaceutical Preparations using π-Acceptors

2012 ◽  
Vol 9 (1) ◽  
pp. 323-329 ◽  
Author(s):  
Sidika Ertürk Toker ◽  
Armagan Önal
Keyword(s):  
Spectrophotometric Determination ◽  
Electron Donor ◽  
Pharmaceutical Analysis ◽  
Antidepressant Drug ◽  
Pharmaceutical Preparations ◽  
Reaction Conditions ◽  
Colored Complex ◽  
Complex Species ◽  
Spectrophotometric Methods

In this study, two simple and accurate spectrophotometric methods were presented for the determination of duloxetine hydrochloride (DLX) in pharmaceutical preparations. The methods were based on the reaction of DLX asn-electron donor with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as π-acceptors to give highly colored complex species. The colored products were quantitated spectro-photometrically at 477 and 841 for DDQ, TCNQ, respectively. All variables were studied in order to optimize the reaction conditions. Beer's law was obeyed in the concentration ranges 10.0-50.0 and 15-60 μg mL−1for DDQ and TCNQ method, respectively. The proposed methods have been successfully applied to the pharmaceutical analysis without any interference from excipients. The suggested procedures could be used for the determination of DLX in pharmaceutical preparations being sensitive, simple and selective.

scholarly journals Spectrophotometric determination of cefixime by charge transfer complex formation

2013 ◽  
Vol 10 (3) ◽  
pp. 971-976
Author(s):  
Baghdad Science Journal
Keyword(s):  
Charge Transfer ◽  
Complex Formation ◽  
Spectrophotometric Determination ◽  
Electron Donor ◽  
Charge Transfer Complex ◽  
Pure Form ◽  
Colored Complex ◽  
Spectrophotometric Methods ◽  
Beer’S Law

Simple, sensitive and economical spectrophotometric methods have been developed for the determination of cefixime in pure form. This method is based on the reaction of cefixime as n-electron donor with chloranil to give highly colored complex in ethanol which is absorb maximally at 550 nm. Beer's law is obeyed in the concentration ranges 5-250 µg ml-1 with high apparent molar absorptivities of 1.52×103 L.mole-1. cm-1.

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