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中国药典1977版特性粘数测定的装置是将乌氏粘度计放入一直径30cm、高40cm以上的玻璃缸或有机玻璃缸中。缸内安有电动搅拌器、电热装置及温度计。特性粘数测定是在一定温度下,以乌氏粘度计中一定量液体的流速(时间以秒作单位)来计算的。所测物的粘度与温度成反比,测定时如温度相差0.1℃,则流速可相差2秒左右,而药典要求2次结果不得相差0.2秒。故上述测定装置由于操作条件很难控制,极易造成误差,其原因有以下3点。 1.电热装置、电动搅拌器、乌氏粘度计同放在一缸中,由于电压不稳,在测定中搅拌器搅拌速度不恒定,搅拌时快时慢,使粘度计所受振动不一;另由于转速不一,水浴内部温度不易一致,使粘度计受热不均匀。这些因素,均影响粘度计中液体的流速,使测定带来误差。
Chinese Pharmacopoeia 1977 version of intrinsic viscosity determination device is to put Ubbelohde viscometer diameter 30cm, 40cm high above the glass or glass cylinder. Cylinder equipped with electric mixer, electric device and thermometer. Intrinsic viscosity is measured at a temperature, the flow rate of a certain amount of Ubbelohde viscometer (time in seconds) to calculate. The measured viscosity and temperature is inversely proportional to the determination of the temperature difference of 0.1 ℃, the flow rate can vary by about 2 seconds, while the Pharmacopoeia requires two results shall not differ by 0.2 seconds. Therefore, the above measuring device is difficult to control due to the operating conditions, which can easily cause errors. The reason for this is as follows. 1. Electric heating device, electric mixer, Ubbelohde viscometer with a cylinder, due to voltage instability, the mixer in the determination of the stirring speed is not constant, mixing fast fast slow, the viscometer suffered vibration; Another due to different speed, the water bath temperature is not easy to uniform, so that uneven heating of the viscometer. These factors, all affect the viscometer in the liquid flow rate, so that the measurement error.