安钠咖注射液是我国药典收载的法定药物制剂,曾用双波长法在四个波长处测定吸收度和三波长法在六个波长处测定吸收度计算苯甲酸钠和咖啡因的含量。本文根据双波长倍增差示法的原理,只需测定两个波长处的吸收度,不用对照品配制标准溶液,即可求得含量。本法操作简易,优于以上方法。测定回收率好,结果准确,值得推广应用。仪器和试剂 Sodium benzoate injection is the Chinese Pharmacopoeia contained in the statutory pharmaceutical preparations, has used dual-wavelength method for the determination of absorbance at four wavelengths and three-wavelength method at six wavelengths measured absorbance calculated sodium benzoate and caffeine content. According to the principle of double-wavelength multiplication differential method, we only need to measure the absorbance at two wavelengths, and then we can get the content without standard solution. This method is simple, better than the above method. Determination of recovery rate, the result is accurate, it is worth to promote the application. Instruments and reagents