Bottari Emilio, D'Ambrosio Antonietta, De Tommaso Gaetano, Festa Maria Rosa, Iuliano Mauro, Meschino Martina
Chemistry Department, Roma University "La Sapienza", P. le A. Moro 5, 00185 Rome, Italy.
Analyst. 2021 Apr 7;146(7):2339-2347. doi: 10.1039/d1an00013f. Epub 2021 Feb 24.
The solubility of folic acid was determined at 25 °C in 1.00 mol dm and in 0.15 mol dm NaCl (physiological solution) spectrophotometrically by measuring the absorbance of saturated solution at different hydrogen ion concentrations. Five protonation constants of folate were determined both from the dependence of the solubility on the hydrogen ion concentration as well as from potentiometric titrations carried out in the presence of solid folic acid and in alkaline solution, in which folate is relatively soluble. Corresponding to the protonation constants, nuclear magnetic resonance and florescence spectra were also obtained at different hydrogen ion concentrations to determine the protonation positions in acid, neutral and alkaline solutions. An approach through circular dichroism was also applied to study the eventual polymerization of folate in alkaline solution.
通过测量饱和溶液在不同氢离子浓度下的吸光度，用分光光度法在25℃测定了叶酸在1.00 mol dm和0.15 mol dm NaCl（生理溶液）中的溶解度。根据溶解度对氢离子浓度的依赖性以及在固体叶酸存在下和叶酸相对易溶的碱性溶液中进行的电位滴定，确定了叶酸的五个质子化常数。对应于质子化常数，还在不同氢离子浓度下获得了核磁共振和荧光光谱，以确定酸、中性和碱性溶液中的质子化位置。还应用了圆二色性方法来研究叶酸在碱性溶液中最终的聚合情况。
