Spectrophotometric Determination of Acidity Constants of Group B Vitamins in Different Ionic Strengths at 25±0.1<sup>°</sup>C

Ghasemi, Jahan B.; Ghobadi, Sirous; Abbasi, Bahman; Kubista, Mikael

doi:10.5012/jkcs.2005.49.3.269

Cited by 17 publications

(10 citation statements)

References 22 publications

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“…The equilibrium constants of Py that were obtained from different converged runs of HSPARAFAC are given in Table VI. It is apparent that the calculated and reported [40] pK a s are in agreement.…”

Section: Hsparafac Analysissupporting

confidence: 76%

“…The acquired pK a s from different converged runs of HPARAFAC are reported in Table VI. These calculated pK a s are in good agreement with HSPARAFAC and literature [40]. Table VI shows the results of the analysis of HPARAFAC under non-negativity constraint in excitation and emission modes.…”

Section: Hparafac Analysissupporting

confidence: 76%

“…À is determined by the equilibrium constants pK a1 and pK a2 for the corresponding protonation steps. The literature pK a values [40] are 4.8 and 9.2 for pK a1 and pK a2 of Py, respectively.…”

Section: The Effect Of Noisementioning

confidence: 99%

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Hard–soft modeling parallel factor analysis to solve equilibrium processes

Sajjadi

Abdollahi

2011

Journal of Chemometrics

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PARAFAC model is the most famous model for analyzing three-way data. However, this method does not converge to chemically meaningful solutions when applied to three-way problems involving rank overlap profiles at least in one mode. Rank overlap can be simply found where components have similar spectral profiles or analytes appearing in identical proportions throughout an experiment. However, an appropriate selection of the initial parameters and constraints such as non-negativity and unimodality can still make PARAFAC model useful in this regard. Although such constraints reduce rotational freedom in PARAFAC solution, they are generally insufficient to wholly eliminate the rotational problem. The goal of the present paper is to incorporate hard modeling constraint in the soft-modeled PARAFAC algorithm to overcome non-uniqueness problem in the equilibrium processes involving linearly dependent factors at least in one mode. The hard constraint is introduced to force some or all of the concentration profiles to fulfill an equilibrium model that is refined at each iteration cycle of the optimization process of PARAFAC. The proposed approach is called hard-soft PARAFAC (HSPARAFAC). When the rank overlap species obeys equilibrium model in HSPARAFAC, the unique results are obtained even in the presence of non-modeled interferences. The new modification in the treatment of equilibrium data sets yields more satisfactory results than the exclusive PARAFAC algorithm. Simulated and real examples with rank overlap problem are used to confirm this statement.

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Section: Hsparafac Analysissupporting

confidence: 76%

Section: Hparafac Analysissupporting

confidence: 76%

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Hard–soft modeling parallel factor analysis to solve equilibrium processes

Sajjadi

Abdollahi

2011

Journal of Chemometrics

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“…The number of released protons in the indicated pH intervals are 1, 2, 3 and 3 for riboflavin, pyridoxal, thiamine and folic acid, respectively. 26 All the molecules show the distinct isosbestic points in a regular changing in pH. As is clear, the system shows a high degree of spectral overlapping of the constitu-ents.…”

Section: Parallel Factor Analysismentioning

confidence: 89%

Simultaneous Spectrophotometric Determination of Group B Vitamins Using Parallel Factor Analysis: PARAFAC

Ghasemi

Abbasi

2005

Jnl Chinese Chemical Soc

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In this work, a simple and rapid analytical procedure was applied for simultaneous determination of folic acid (vitamin B0), thiamin (vitamin B 1 ), riboflavin (vitamin B 2 ) and pyridoxal (vitamin B 6 ) based on the absorbance data in the pH range 2.0-12.0 at 25°C using parallel factor analysis (PARAFAC). The effect of the pH as the most important factor on the sensitivity of the determination was studied. The spectral data were recorded in 400-650 nm intervals and a 2-12 pH range for all four vitamins. The calibration set was constructed in the concentration ranges of 4-22, 1-20, 6-26, and 4-20 mg mL -1 for B 6 , B 2 , B 1 and B 0 , respectively. The root mean squares errors of prediction for the prediction set, (RMSEP), are 0.65, 0.63, 1.13 and 0.34 for B0, B 1 , B 2 and B6, respectively. The recovery percent for the validation set are in the range of 90.6 to 107.0%. The effect of the experimental conditions and diverse species were discussed. The optimum values of these factors were searched according to the relative standard deviation of the prediction set of mixtures solutions.

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“…Vitamin B9 (FA) is one of the most biologically important compounds, and information about their metal ions complexation properties are rare in the literature. However, the interaction between some transition metal ions and vitamin B9 resulted in the formation of a number of binary transition metals-FA complexes in which number of drugs can interfere FA supplement [7][8][9][10][11][12][13][14]. The present study was done to determine the global stoichiometric stability constants of calcium/zinc/iron metal ions, FA, and Gly binary and mixed ligand complexes using potentiometric technique, and by applying the row data on Hyperquad 2008 computer program.…”

Section: Introductionmentioning

confidence: 99%

Stability constants and complex formation equilibria between iron, calcium, and zinc metal ions with vitamin B9 and glycine

Fazary¹,

Ramadan

2014

Complex Metals

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To cite this article: Ahmed E. Fazary & Ahmed M. Ramadan (2014) Stability constants and complex formation equilibria between iron, calcium, and zinc metal ions with vitamin B9 and glycine, Complex Metals, 1:1, 139-148,The complexation equilibria of folic acid (FA) and glycine (Gly) were studied in aqueous solutions at room temperature (ca. 298.15 K) and in fixed ionic strength (0.15 mol.dm −3 NaNO 3 ), by means of potentiometry technique. The ferric (Fe 3+ ), ferrous (Fe 2+ ), calcium (Ca 2+ ), and zinc (Zn 2+ ) complex-forming capacities of FA and Gly, and their overall stability constants in aqueous solutions were obtained by applying the potentiometric data in Hyperquad 2008 computer program. From the determined stability constants of the metal complex species, the concentration distribution of the various metal ion complex species involving FA and Gly in solutions was estimated using HySS 2009 software. The complex species distribution diagrams were explained and discussed. Supplementary, the Gibbs free energies and the molecular structures of the formed complexes were evaluated and predicted using Gaussian 09 software molecular modeling and calculations.

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Spectrophotometric Determination of Acidity Constants of Group B Vitamins in Different Ionic Strengths at 25±0.1^°C

Cited by 17 publications

References 22 publications

Hard–soft modeling parallel factor analysis to solve equilibrium processes

Hard–soft modeling parallel factor analysis to solve equilibrium processes

Simultaneous Spectrophotometric Determination of Group B Vitamins Using Parallel Factor Analysis: PARAFAC

Stability constants and complex formation equilibria between iron, calcium, and zinc metal ions with vitamin B9 and glycine

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Spectrophotometric Determination of Acidity Constants of Group B Vitamins in Different Ionic Strengths at 25±0.1°C

Cited by 17 publications

References 22 publications

Hard–soft modeling parallel factor analysis to solve equilibrium processes

Hard–soft modeling parallel factor analysis to solve equilibrium processes

Simultaneous Spectrophotometric Determination of Group B Vitamins Using Parallel Factor Analysis: PARAFAC

Stability constants and complex formation equilibria between iron, calcium, and zinc metal ions with vitamin B9 and glycine

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Spectrophotometric Determination of Acidity Constants of Group B Vitamins in Different Ionic Strengths at 25±0.1^°C