Potentiometric and UV–Vis Spectroscopy Studies of Citrate with the Hexaquo Fe<sup>3 +</sup> and Cr<sup>3 +</sup> Metal Ions

Hamada, Yahia Z.; Carlson, Brandon L.; Shank, Jeremy T.

doi:10.1081/sim-120024320

Cited by 43 publications

(32 citation statements)

References 13 publications

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“…In potentiometric titrations, the equivalent of added base is defined as the number of moles of NaOH per number of moles of the sample under determination (phosphoric acid in this case). The definition of equivalent has been used before [5,6,9,[25][26][27][28][29]. the observed pH versus the potential in millivolts.…”

Section: System Standardizationmentioning

confidence: 99%

“…The methods used to prepare, standardize, and prevent the contamination of the titrant with atmospheric CO 2 have been described elsewhere [5,6,9,[27][28][29]. The interaction of Cr 3+ with Asp was monitored in different Cr 3+ to Asp molar ratios typically 0 : 1, 1 : 0, 1 : 1, 1 : 2, and 1 : 3 molar ratios.…”

Section: Potentiometric Titrations and Distribution Diagramsmentioning

confidence: 99%

“…In a typical titration system, Asp solution was added; then the equivalent of the Cr 3+ ion solution followed by dilution to 100 mL total volume with DI water. The total concentration of metal ions was set to 1.0 × 10 −3 M, which is typical for potentiometric titrations [5,6,8,9,[23][24][25][26][27]. Before each titration, the metal-Asp mixtures were allowed to stir for 15-20 min to reach a state of equilibrium.…”

Section: Potentiometric Titrations and Distribution Diagramsmentioning

confidence: 99%

“…Although there are many studies regarding essential Cr 3+ , the isolation and characterization * Corresponding author. Email: yahia_hamada@loc.edu of this LMMCr complex has not been achieved, and thus its precise structure is still unknown [5,6,9]. In mammals, Asp is a known neurotransmitter [22].…”

Section: Introductionmentioning

confidence: 99%

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Reactions of Cr³⁺ with aspartic acid within a wide pH range

et al. 2014

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Formation of the metal complexes of aspartic acid (Asp) with the chromium metal ion (Cr 3+ ) in solutions using potentiometric titrations is presented within a wide pH range (∼3.5 to ∼10.5) at 25 • C and I = 0.10 M NaNO 3 . Concentration distribution diagrams revealed that the main complex formed within this pH range is the bis Cr 3+ complex. Literature stability constant values for the Cr-Asp complexes were used to construct concentration distribution diagrams. Complexes taken into consideration were the simple one-to-one complex, the bis-complex, and the bis-mono-protonated complex, namely, Cr-Asp, Cr(Asp) 2 , and Cr(Asp) 2 H. The corresponding Log β values of these complexes were 12.46, 21.86, and 24.30, respectively. UV-Vis spectra demonstrate Cr 3+ -Asp binding. The UV-Vis spectra were collected from a system that reached a high level of equilibrium state (50 days' equilibrium time).

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Section: System Standardizationmentioning

confidence: 99%

Section: Potentiometric Titrations and Distribution Diagramsmentioning

confidence: 99%

Section: Potentiometric Titrations and Distribution Diagramsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Reactions of Cr³⁺ with aspartic acid within a wide pH range

et al. 2014

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“…NaOH solutions were prepared from NaOH laboratory grade pellets in carbonate free water. The methods used to prevent the contamination of the titrant with atmospheric CO 2 had been described elsewhere [10][11][12][13][14][15]. The NaOH solutions were standardized using primary standard potassium hydrogen phthalate (KHP).…”

Section: Chemicals/solutionsmentioning

confidence: 99%

Cu2+ Complexes with the Simplest Amino Acid Glycine (Gly)

Hamada¹,

Makoni²,

Hamada³

2017

JNMR

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Using potentiometric titrations, UV-Vis, IR and speciation diagrams, it appeared that the simplest amino acid Glycine (Gly) is not reacting in a simple manner at all with the copper metal ion (Cu 2+ ) in aqueous solutions at 25˚C. The potentiometric measurements indicated that Cu 2+ released a net of two protons (2H + 's) into the solution. Free Gly released one proton (H + ) into the solution from the single ammonium group. On the other hand, when Glycine hydrochloride (Gly.HCl) was used instead of free Gly, both the carboxylate and the ammonium groups released their protons. Upon the reaction of Cu 2+ with Gly.HCl in any molar ratio, a net of four protons (4H + 's) or more were released into the solution; one H + from the carboxylic acid group, the second from the ammonium group and the additional two H + 's from the Cu 2+ -aqua ligands. The proposed solution species are in a good agreement with what has been shown in the literature.Keywords: Aqueous solutions; Glycine; Potentiometry; Zwitterion

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