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首页> 外文期刊>Journal of pharmaceutical sciences. >High-precision absolute (true) density measurements on hygroscopic powders by gas pycnometry: application to determining effects of formulation and process on free volume of lyophilized products.
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High-precision absolute (true) density measurements on hygroscopic powders by gas pycnometry: application to determining effects of formulation and process on free volume of lyophilized products.

机译：气体比重瓶法对吸湿性粉末进行高精度绝对（真）密度测量：用于确定制剂和工艺对冻干产品自由体积的影响。

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摘要

As density (free volume) of the amorphous solids should be related to mobility and stability, an attempt was made to develop a simple, sensitive, and reproducible method to evaluate free volume via high-precision gas pycnometry density measurements, and to apply this methodology to study the variation of free volume with formulation and thermal history (i.e., annealing). Annealed samples were prepared either by heating the product after freeze drying (postannealing) or drying at higher temperature in secondary drying than normal (in-process annealing). Density was measured using a gas pycnometer. We find that the key to high-precision density measurements is isolation of the instrument from atmospheric moisture; accordingly, all operations were carried out in a dry box. With suitable care, densities of amorphous freeze-dried products can be measured with a precision of better than 0.5% in a series of independent but nominally identical samples. Density decreased with increasing molecular weight of dextran, but density of proteins was independent of molecular weight. Small but significant increases in density upon annealing were observed for several formulations. Thus, we conclude that accurate density measurements may be made by carefully controlling residual moisture. Density may be a useful parameter to predict long-term stability.
机译：由于无定形固体的密度（自由体积）应与迁移率和稳定性相关，因此尝试开发一种简单，灵敏且可重现的方法，以通过高精度比重瓶比重法测量自由体积，并应用此方法研究自由体积随配方和热历史（即退火）的变化。通过在冷冻干燥后加热产品（后退火）或在二次干燥中以高于正常温度的温度干燥（过程中退火）来制备退火样品。使用气体比重瓶测量密度。我们发现，高精度密度测量的关键是将仪器与大气中的水分隔离开。因此，所有操作均在干燥箱中进行。通过适当的注意，在一系列独立但名义上相同的样品中，非晶态冷冻干燥产品的密度可以以优于0.5％的精度进行测量。密度随葡聚糖分子量的增加而降低，但蛋白质的密度与分子量无关。对于几种配方，观察到退火后密度有微小但显着的增加。因此，我们得出结论，可以通过仔细控制残留水分来进行准确的密度测量。密度可能是预测长期稳定性的有用参数。

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