Wurster D E, Buraphacheep V, Patel J M
University of Iowa, College of Pharmacy, Iowa City 52242.
Pharm Res. 1993 Apr;10(4):616-20. doi: 10.1023/a:1018922724566.
A Fourier transform infrared (FT-IR) spectrometer with a horizontal attenuated total reflectance (ATR) cell was used to determine the diffusion coefficients of several liquids in two semisolid materials. The experimental setup was that of a system with one open and one closed boundary wherein the open boundary was maintained at constant concentration. While the liquid of interest was diffusing through the film of ointment, the concentration of liquid at the film surface in contact with the ATR crystal was determined at various times by means of IR absorption measurements. The depth of penetration of the IR radiation into the sample was approximately 0.6-0.9 microns at the wavelengths of analysis. Since the ointment thickness was 157 microns, it was reasonable to assume that only the penetrant reaching the lower boundary was being measured. The values of the diffusion coefficients were then calculated using an equation that appropriately modeled the aforementioned conditions. The liquids tested exhibited diffusion coefficients in anhydrous lanolin and in polyethylene glycol ointment that ranged from 0.56 to 7.2 x 10(-7) and 0.68 to 5.7 x 10(-7) cm2/sec, respectively. The expected molecular weight dependency was observed.
使用配备水平衰减全反射（ATR）池的傅里叶变换红外（FT-IR）光谱仪来测定几种液体在两种半固体材料中的扩散系数。实验装置是一个具有一个开放边界和一个封闭边界的系统，其中开放边界保持在恒定浓度。当感兴趣的液体扩散通过软膏膜时，通过红外吸收测量在不同时间确定与ATR晶体接触的膜表面处液体的浓度。在分析波长下，红外辐射进入样品的穿透深度约为0.6 - 0.9微米。由于软膏厚度为157微米，合理假设仅测量到达下边界的渗透剂。然后使用适当模拟上述条件的方程计算扩散系数值。所测试的液体在无水羊毛脂和聚乙二醇软膏中的扩散系数分别为0.56至7.2×10⁻⁷和0.68至5.7×10⁻⁷ cm²/秒。观察到了预期的分子量依赖性。
