Telang Chitra, Suryanarayanan Raj, Yu Lian
College of Pharmacy, University of Minnesota, Minneapolis, MN 55455, USA.
Pharm Res. 2003 Dec;20(12):1939-45. doi: 10.1023/b:pham.0000008040.14958.bc.
To study the crystallization, polymorphism, and phase behavior of D-mannitol in binary mixtures with NaCl to better understand their interactions in frozen aqueous solutions.
Differential scanning calorimetry, hot-stage microscopy, Raman microscopy, and variable-temperature X-ray diffractometry were used to characterize D-mannitol-NaCl mixtures.
NaCl and D-mannitol exhibited significant melt miscibility (up to 7.5% w/w or 0.20 mole fraction of NaCl) and a eutectic phase diagram (eutectic composition 7.5% w/w NaCl; eutectic temperature 150 degrees C for the alpha and beta polymorphs of D-mannitol and 139 degrees C for the delta). The presence of NaCl did not prevent mannitol from crystallizing but, depending on sample size, affected the polymorph crystallized: below 10 mg, delta was obtained; above 100 mg, alpha was obtained. Pure mannitol crystallized under the same conditions first as the delta polymorph and then as the a polymorph, with the latter nucleating on the former. KCl showed similar eutectic points and melt miscibility with D-mannitol as NaCl. LiCl yielded lower eutectic melting points, inhibited the crystallization of D-mannitol during cooling, and enabled the observation of its glass transition.
Despite their structural dissimilarity, significant melt miscibility exists between D-mannitol and NaCl. Their phase diagram has been determined and features polymorph-dependent eutectic points. NaCl influences the polymorphic behavior of mannitol, and the effect is linked to the crystallization of mannitol in two polymorphic stages.
研究D - 甘露醇与氯化钠二元混合物的结晶、多晶型及相行为，以更好地理解它们在冷冻水溶液中的相互作用。
采用差示扫描量热法、热台显微镜、拉曼显微镜和变温X射线衍射法对D - 甘露醇 - 氯化钠混合物进行表征。
氯化钠和D - 甘露醇表现出显著的熔融混溶性（氯化钠含量高达7.5% w/w或0.20摩尔分数）以及共晶相图（共晶组成7.5% w/w氯化钠；D - 甘露醇的α和β多晶型的共晶温度为150℃，δ多晶型为139℃）。氯化钠的存在并不妨碍甘露醇结晶，但根据样品量的不同，会影响结晶的多晶型：低于10 mg时，得到δ型；高于100 mg时，得到α型。在相同条件下，纯甘露醇首先结晶为δ多晶型，然后转变为α多晶型，后者以前者为晶核。氯化钾与D - 甘露醇的共晶点和熔融混溶性与氯化钠相似。氯化锂产生较低的共晶熔点，抑制冷却过程中D - 甘露醇结晶，并能观察到其玻璃化转变。
尽管D - 甘露醇和氯化钠结构不同，但它们之间存在显著的熔融混溶性。已确定它们的相图，其具有依赖多晶型的共晶点。氯化钠影响甘露醇的多晶型行为，且该效应与甘露醇在两个多晶型阶段的结晶有关。
