Potentiometric Titration Study of the Temperature and Ionic Strength Dependence of the Acidity Constants of Nicotinic Acid (Niacin)

Gonçalves, Elsa; Joseph, Abhinav; Conceição, António C. L.; Piedade, Manuel E. Minas da

doi:10.1021/je200263g

Cited by 30 publications

(7 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The FA or MA content was further determined by UV–vis spectrophotometry at 210 and 206 nm, respectively. The titrations were carried out with a Radiometer Analytical pHC3001-9 combined pH electrode and a previously described setup and procedure . Spectrophotometric measurements were performed on a Shimadzu UV-1800 apparatus equipped with a TCC-240A cell holder connected to a TCC temperature controller.…”

Section: Materials and Methodsmentioning

confidence: 99%

Energetics of Glycine Cocrystal or Salt Formation with Two Regioisomers: Fumaric Acid and Maleic Acid

Évora

Bernardes

Piedade

et al. 2019

Crystal Growth & Design

Self Cite

View full text Add to dashboard Cite

Multicomponent crystals have received significant attention in recent years, given their considerable potential to develop new products or improve the properties of known ones. Many studies have examined the synthesis and structure of multicomponent (mostly binary) crystals. The thermodynamic aspects related to the driving force for their formation and stability are, however, still relatively unexplored. This work describes a structure–energetics study of binary crystals consisting of glycine (Gly) and fumaric acid (FA) or maleic acid (MA), two regioisomers with different proton transfer abilities. Single-crystal X-ray diffraction experiments showed that the mechanochemically synthesized materials corresponded to a new FA:Gly2 cocrystal and a MA:Gly salt that had been previously prepared by crystallization from solution. A packing analysis further suggested that the stoichiometry difference (1:2 vs 1:1) is possibly related to differences in hydrogen bonding ability between FA and MA. Calorimetric and solubility measurements indicated that: (i) The two binary crystals are stable relative to decomposition into their precursors under ambient conditions (298.15 K; 1 bar), since the process is endergonic (Δr G m° > 0) in both cases. (ii) The stability is of enthalpic nature because Δr H m° > 0 and Δr H m° > |TΔr S m°|. (iii) The formation of a salt, rather than a cocrystal, does not bring any notable stability advantage, since the obtained Δr G m° for MA:Gly exceeds that found for FA:Gly2 by ∼1.0 kJ·mol–1 only. (iv) The similarity appears to be originated by an enthalpy–entropy compensation effect: the Δr H m° contribution (reflecting lattice enthalpy differences between the binary crystals and their components) is approximately twice as large for MA:Gly than for FA:Gly2, but the difference is balanced, to a considerable extent, by a larger and opposing TΔr S m° contribution. (v) The number of classical hydrogen bonds established by a FA or MA molecule with Gly does not seem to be a reliable predictor of stability, as six of these bonds are present in FA:Gly2 and only four in MA:Gly. (vi) Finally, the results here obtained show that the formation of a binary crystal is not necessarily advantageous in terms of solubility enhancement. Indeed, while the solubility of FA from FA:Gly2 was found to be ∼4 times larger than that of pure FA, no analogous benefit was observed for the MA:Gly salt, which exhibited a ∼3 times lower MA solubility when compared with pure MA.

show abstract

Section: Materials and Methodsmentioning

confidence: 99%

Energetics of Glycine Cocrystal or Salt Formation with Two Regioisomers: Fumaric Acid and Maleic Acid

Évora

Bernardes

Piedade

et al. 2019

Crystal Growth & Design

Self Cite

View full text Add to dashboard Cite

show abstract

“…Several analytical studies followed, using TLC [10][11][12][13][14], spectrophotometric [15][16][17][18], and HPLC methods [19][20][21]. Capillary electrophoresis and HPLC methods were Separations 2021, 8, 46 2 of 11 developed to determine NIA in foods [22] via autoclaving at 121 • C in the presence of 0.8 M sulfuric acid for 2 h. Potentiometric and voltametric studies have also been reported in the literature [23,24]. Although the thermal stability of NIA was a controversial topic [25], many gas chromatographic methods were developed for the determination of NIA in food samples and in enzymes, relying on short analysis time, low molecular weight of NIA and high volatility [25,26].…”

Section: Introductionmentioning

confidence: 99%

Eco-Friendly Direct GC–MS Method for Estimation of Niacin and Related Impurities Involving Pyridine in Food Supplements

2021

View full text Add to dashboard Cite

Niacin is a water-soluble vitamin whose deficiency causes many disorders and diseases, including pellagra and high blood cholesterol. Herein, niacin and four common impurities, isonicotinic acid (ISO), 5-ethyl-2-methylpyridine (MP), pyridine-2, 5-dicarboxylic acid (PDC) and pyridine PYR, are simultaneously analyzed, where PYR is known as potentially nephrotoxic and hepatotoxic. The separation of a mixture using gas chromatography–mass spectroscopy (GC–MS) without any derivatization steps was the main target. Many studies have been published to study Niacin and its impurities using colorimetry and HPLC. GC–MS was selected to study the analyzed mixture owing to its known sensitivity and selectivity. In this study, a single quadrupole mass spectrometer operated in selected ion monitoring (SIM) mode at an electron ionization energy of 70 eV was applied for the quantitative analysis of Niacin. Helium was used as the carrier gas and adjusted to run through an HP-5ms (5%-phenyl)-methylpolysiloxane column. Statistical analysis proved that this method is equally effective as the previously reported method. Importantly, this study was eco-friendly as compared to the reported high performance thin layer chromatographic method (HPTLC). Finally, this study provides a new and valid eco-friendly method analysis to determine the concentration of niacin and its common impurities at very low concentration. Conclusion: A simple, rapid accurate and green GC–MS analytical method was developed and validated to determine niacin and its related official impurities.

show abstract

“…The high nonlinear efficiency of an organic material is due to the long wavelength absorption edge since they have delocalised conjugated π electron to enhance the nonlinear hyper polarizability [7]. The organic NLO materials have excellent applications in optical data storage, optical information processing, electro optical modulation, telecommunication, etc., [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Investigation on the optical, mechanical and magnetic properties of organic NLO single crystal: Pyridine 3-carboxylic acid

Deepa

Philominathan

2016

Optik

View full text Add to dashboard Cite

Potentiometric Titration Study of the Temperature and Ionic Strength Dependence of the Acidity Constants of Nicotinic Acid (Niacin)

Cited by 30 publications

References 55 publications

Energetics of Glycine Cocrystal or Salt Formation with Two Regioisomers: Fumaric Acid and Maleic Acid

Energetics of Glycine Cocrystal or Salt Formation with Two Regioisomers: Fumaric Acid and Maleic Acid

Eco-Friendly Direct GC–MS Method for Estimation of Niacin and Related Impurities Involving Pyridine in Food Supplements

Investigation on the optical, mechanical and magnetic properties of organic NLO single crystal: Pyridine 3-carboxylic acid

Contact Info

Product

Resources

About