用汞灯365 nm测量氢溴酸右美沙芬的旋光
Optical rotation of Dextromethorphan Hydrobromide in accordance with the U.S. Pharmacopeia, isrequested to be measured at 325 nm, however there is no emission line of 325 nm available in the polarimeterusing Na lamp or Hg lamp as light source. Therefore, for the measurement of optical rotation ofDextromethorphan Hydrobromide, a polarimeter with halogen lamp as a light source and interference filter(325 nm) has been usually used, but as shown in Fig. 1, the optical rotatory dispersion (ORD) spectrum, thereis a very steep slope in the short wavelength range near 325 nm, where even a very small error in thewavelength of interference filter may cause a very large error in the optical rotation measurement, which willmakes the accurate measurements very difficult. On the other hand, if the measurement by using 365nm isallowed, since no wavelength error is expected, the measurement of optical rotation can be implemented withmuch higher accuracy. In this experiment, Dextromethorphan Hydrobromide was measured usingpolarimeter with Hg lamp (365 nm), polarimeter with Halogen lamp and interference filter (325 nm) andpolarimeter with ORD attachment.