麻黄鹼的高碘酸比色测定法

虽然麻黄鹼早在1885年已从麻黄草中分出,并且在1920年已经人工合成,但是麻黄鹼的含量测定,迄今仍缺乏满意的方法。考查文献上所见的麻黄鹼的含量测定法,主要可归纳为二大类,就是酸鹼滴定法和比色法。中华人民共和国药典(中国药典)的方法所根据的原理是先用鹼使样品(麻黄鹼鹽类的纯品或麻黄流浸膏)中的麻黄鹼游离,继用醚抽出,然后采用酸鹼滴定。英国药典和美国药典的含量测定法也如上述。这法的缺点是:(1)用醚和酸液反复抽取,手续麻

THE COLORIMETRIC DETERMINATION OF EPHEDRINE WITH PERIODIC ACID

The colorimetric method for the determination of ephedrine and its preparations with periodic acid is reported. Ephedrine hydrochloride is oxidized with periodate at a pH about 7.2, buffered with phosphate, the acetaldehyde thus produced is separated from the reaction mixture by aeration and absorbtion in concentrated sulfuric acid, to which p-hydroxy biphenyl being added after aeration. The optical density of the bluishviolet color formed is compared with a standard graph using an electrophotometer. In the method specified, samples containing 0.005—0.05 mg ephedrine hydrochloride can be determined with an accuracy within ±5%. Factors which affect the color are studied. Lactose and glycerin give no interference. Data and details for using the method to determine ephedrine in fluid-extract and tablets are also given.