Elsergany Ramy N, Vreeman Gerrit, Sun Changquan Calvin
Pharmaceutical Materials Science and Engineering Laboratory, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, MN 55455, USA.
Pharmaceutical Materials Science and Engineering Laboratory, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, MN 55455, USA.
Int J Pharm. 2023 Apr 25;637:122875. doi: 10.1016/j.ijpharm.2023.122875. Epub 2023 Mar 21.
Helium pycnometry, a commonly used technique for measuring the true density of powders, is sensitive to the release of volatiles during measurement. This can lead to over-estimated true density, and as such, an accurate method for determining the true density of powders containing volatile components is needed. Here, a method based on in-die compression data obtained with a compaction simulator was assessed. Specifically, the stress transmission coefficient (STC), measured using an instrumented die, was used to predict the in-die Heckel mean yield pressure (P). A true density was derived by repeatedly performing a Heckel analysis using iteratively estimated true density values until the predicted P value from the measured STC value is obtained from in-die density - pressure data. This novel method was validated using a set of water-free powders. Using crystalline hydrates, we further showed that the calculated true densities were closer to values calculated from crystal structure than those from helium pycnometry. Hence, this method may be used for determining the true density of powders from their STC values.
氦比重瓶法是一种常用的测量粉末真密度的技术，在测量过程中对挥发物的释放很敏感。这可能导致真密度被高估，因此，需要一种准确的方法来测定含有挥发性成分的粉末的真密度。在此，评估了一种基于压实模拟器获得的模内压缩数据的方法。具体而言，使用仪器化模具测量的应力传递系数（STC）用于预测模内赫克尔平均屈服压力（P）。通过使用迭代估计的真密度值反复进行赫克尔分析，直到从模内密度-压力数据中获得根据测量的STC值预测的P值，从而得出真密度。使用一组无水粉末对这种新方法进行了验证。使用结晶水合物，我们进一步表明，计算得到的真密度比用氦比重瓶法得到的结果更接近根据晶体结构计算的值。因此，该方法可用于根据粉末的STC值测定其真密度。
