4028. Quinidine

4028.     Quinidine. An alkaloid found in quinia which has been prepared by precipitation. It is distinguished from quinine by not striking a green color when treated with chlorine followed by ammonia, as quinine does. In medicinal character its powers are comparatively feeble. It is present in nearly all the ordinary sulphate (disulphate) of quinine as sold, either through careless preparation or wilful adulteration, and is not detected by, and consequently included in, the results of the usual tests for quinine. (See Nos. 4025 (Quinometry), etc..) Cinchonine is another feebler alkaloid also found in quinia.

4029. Ure's Test for the Presence of Quinidine or Cinchonine in Quinine

4029.     Ure's Test for the Presence of Quinidine or Cinchonine in Quinine. This test is applicable to quinine salts generally, but more especially refers to the sulphate (disulphate) of quinine. Place 10 grains of the salt into a strong test tube, furnished with a tightly-fitting cork; add 10 drops of a mixture of 1 part sulphuric acid and 5 parts water, and 15 drops water, accelerating solution by a gentle heat. When dissolved and entirely cooled, add 60 drops officinal sulphuric ether with 20 drops spirits of ammonia, close the test tube with the thumb, and shake it well; cork the tube closely and shake gently from time to time, so that the bubbles of air may readily enter the layer of ether. If the salt be free from, or contain no greater proportion than 10 per cent, of quinidine, it will be entirely dissolved; while on the surface of contact between the two strata of fluid, the mechanical impurities only will be separated. From this it appears that 10 grains of the salt may contain 1 grain of quinidine, and still a complete solution take place; but, in this case, the quinidine will shortly begin to crystallize in a layer of ether. If more than 10 per cent, of quinidine be present, there will be found an insoluble precipitate between the strata of the fluid. If this be quinidine, it will be dissolved by the addition of ether, while cinchonine (see No. 4002 (Cinchonine, or Cinchonia)) will be unaffected.