Non-invasive monitoring of the mixing of pharmaceutical powders by broadband acoustic emission
Non-invasive monitoring of the mixing of pharmaceutical powders by broadband acoustic emission
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DOI：
10.1039/b922446g
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发表时间：
2010-01-01
期刊：
影响因子：
4.2
通讯作者：
Littlejohn, David
中科院分区：
文献类型：
--
作者：
Allan, Pamela;Bellamy, Luke J.;Littlejohn, David
宽带声换能器，包括本质安全的设备，进行了评估，在实验室规模的对流搅拌器中的阿司匹林，柠檬酸或Avicel混合的非侵入性监测。声发射（AE）频谱的频率信息内容取决于换能器的响应特性，其根据设计而变化。当由颗粒的冲击产生的声波传播通过玻璃混合容器和围绕玻璃混合容器时，从玻璃上的不同位置获得可比较的光谱。声发射强度随转速、粉体质量或颗粒密度的增大而增大。AE也随着颗粒尺寸的增加而增加，在较低频率下强度增加相对较大。在向Avicel中加入阿司匹林时，根据选定频率范围内的积分强度变化，在真实的时间内生成混合曲线; AE信号最初增加，然后随着混合物变得均匀而达到平台。对Avicel中三种不同粒径范围的阿司匹林的平均平台信号对浓度作图;对于阿司匹林浓度21% m/m阿司匹林，AE的增加比例更大，粒径效应更明显。该研究表明，在粉末混合过程中，AE相对容易进行非侵入性测量，但在检测添加次级化合物引起的影响方面，特别是在较小的颗粒尺寸下，AE的灵敏度低于NIR光谱法。
Broadband acoustic transducers, including an intrinsically safe device, were assessed for non-invasive monitoring of aspirin, citric acid or Avicel mixing in a bench scale convective blender. The frequency information content of the acoustic emission (AE) spectra depends on the response characteristics of the transducers, which vary depending on the design. As acoustic waves generated from the impact of particles propagated through and around the glass mixing vessel, comparable spectra were obtained from different locations on the glass. The intensity of AE increased as the impeller speed, mass of powder or density of the particles was increased. AE also increased with particle size, with a relatively greater increase in intensity at lower frequencies. Mixing profiles were generated in real time from the change in the integrated intensity over selected frequency ranges on addition of aspirin to Avicel; the AE signal initially increased and then came to a plateau as the mixture became homogeneous. The average plateau signal was plotted against concentration for three different particle size ranges of aspirin in Avicel; for aspirin concentrations 21% m/m aspirin, there was a proportionally greater increase in AE, and particle size effects were more obvious. The study has shown that AE is relatively easy to measure non-invasively during powder mixing, but has poorer sensitivity than NIR spectrometry for detection of effects caused by addition of secondary compounds, especially at smaller particle sizes.