The use of dynamic vapour sorption and near infra-red spectroscopy (DVS-NIR) to study the crystal transitions of theophylline and the report of a new solid-state transition.
The use of dynamic vapour sorption and near infra-red spectroscopy (DVS-NIR) to study the crystal transitions of theophylline and the report of a new solid-state transition.
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利用动态蒸气吸附和近红外光谱（DVS-NIR）研究茶碱的晶体转变并报告了新的固态转变。
DOI：
10.1016/j.ejps.2004.01.009
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
D. Clapham
中科院分区：
文献类型：
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作者：
Ketan L Vora;G. Buckton;D. Clapham
这项研究是为了看看是否DVS-NIR的联合技术可以增加对茶碱物理形式之间转变的理解。质量变化与近红外峰强度之间有很好的相关性，表明水合物正在形成和丢失。1478和1972nm处的峰表示OH变形。近红外光谱分析表明，脱水产物保留了水合物和无水合物的部分晶格结构。在脱水过程中发现了一个新的转变。在40 - 50% RH之间发生了意外的质量损失。通常，吸水过程中的质量损失是无定形材料结晶的特征，尽管在这种情况下，样品可能是结晶的。近红外光谱数据表明，在这一转变过程中，脱水峰恢复到无水茶碱的峰位置。脱水物对水的吸收使得形成稳定的无水晶格的运动自由。结果表明，DVS-NIR是研究茶碱固态转变的有效工具，并且茶碱脱水转化为无水的转变是通过吸附水促进的。
This study was undertaken to see if the combined technique of DVS-NIR could add to the understanding of transitions between physical forms of theophylline. There was excellent correlation between the mass changes and the intensity of the NIR peaks, showing that the hydrate was being formed and lost. This was characterised by the peaks at 1478 and 1972nm representing an OH deformation. NIR spectra for desorption shows that the dehydrate retains partial structure of both the anhydrate and hydrate crystal lattices. During rehydration of the dehydrate a new transition was discovered. An unexpected mass loss occurred between 40 and 50% RH. Usually, a mass loss during water sorption is characteristic of crystallisation of an amorphous material, although in this case it could be that the sample is crystalline. NIR data showed that during this transition the dehydrate peaks reverted back to the peak positions seen for anhydrous theophylline. The absorption of water into the dehydrate allowed the freedom of movement for the stable anhydrous lattice to form. It was concluded that DVS-NIR is a useful tool to study solid-state transitions and that the transition exists for conversion of theophylline dehydrate to anhydrate which is facilitated through water sorption.