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目的:建立Gd-DTPA顺磁性脂质体包封率的测定方法。方法:采用薄膜分散-高压均质法制备顺磁性(Gd-DTPA)脂质体。分别采用透析法、超速离心法、超滤离心法分离脂质体和游离药物,并用电感耦合等离子体-原子发射光谱法(ICP-AES)测定其中钆的含量,计算脂质体包封率。结果:ICP-AES法测定钆浓度在2～10mg·L-1范围内线性关系良好(r=0.9996);高、中、低3种浓度的日内和日间精密度试验的RSD均小于1%;消解方法的平均回收率(98.1%～100.3%)符合要求;3种包封率测定方法中超滤离心法测得的包封率最高,透析法测得的包封率最低。结论:超滤离心法结合ICP-AES法快捷、准确,适用于Gd-DTPA顺磁性脂质体包封率的测定。
Objective: To establish a method for determination of entrapment efficiency of Gd-DTPA paramagnetic liposomes. Methods: Paramagnetic (Gd-DTPA) liposomes were prepared by membrane dispersion-high pressure homogenization. Liposomes and free drugs were separated by dialysis, ultracentrifugation and ultrafiltration respectively. The content of gadolinium was determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES), and the liposome entrapment efficiency was calculated. Results: The determination of gadolinium concentration in the range of 2 ~ 10 mg · L-1 by ICP-AES showed a good linearity (r = 0.9996). The RSDs of intraday and interday precision of three concentrations of high, medium and low were less than 1% ; The average recoveries of the digestion method (98.1% ~ 100.3%) met the requirements; the entrapment efficiency of the three methods for determination of entrapment efficiency was the highest as measured by ultrafiltration centrifugation, and the entrapment efficiency was the lowest as measured by dialysis. Conclusion: Ultrafiltration centrifugation combined with ICP-AES method is fast and accurate and suitable for the determination of entrapment efficiency of Gd-DTPA paramagnetic liposomes.