阿司匹林结晶过程的在线分析

晶体的颗粒尺寸分布和形状是结晶产品的两个关键质量指标，不仅影响结晶产品的性质，还影响下游的过滤、干燥及运输存储等过程。利用超声粒度分析仪、衰减全反射傅里叶红外光谱仪、浊度仪与二维成像系统等分析仪器在线测量了不同搅拌速率和不同降温速率下阿司匹林乙醇溶液结晶过程中温度、浓度、颗粒尺寸分布和形状的变化情况。实验结果表明：较低的降温速率或者较大的搅拌速率条件下得到含有大量细晶的阿司匹林结晶产品；较高的降温速率下得到长宽比较大的阿司匹林结晶产品。调节降温速率和搅拌速率是一种有效控制阿司匹林结晶产品尺寸分布与形状的方法。

Online monitor of Aspirin crystallization process

Size distribution and geometry are key properties of crystal products, which can affect product quality and downstream processes of filtration, drying, storage and transportation. An on-line process analysis system, including ultrasonic particle size analyzer, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), turbidity analyzer and two-dimensional imaging system, was developed to monitor crystallization of Aspirin ethanol solution at various stirring and cooling rates. The results show that lower cooling or faster stirring rate produces more amount of fine crystals and higher cooling rate yields product with larger mean size and higher aspect ratio (AR). Therefore, adjusting cooling and stirring rate is an effective technique to control particle size distribution and shape of Aspirin crystals.