Licence: Attribution 4.0 International (CC BY 4.0)
Credit: The tests for purity of quinine salts / by Frank Tutin. Source: Wellcome Collection.
Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.
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![the result of the-test, but of a nature opposite to that pro- duced by the sulphates. Thus when a sample of pure quinine sulphate was tested according to the French method, but with the addition of two molecular proportions of either sodium or potassium chloride, 8'5—8 6 C.c. of ammonia were required, instead of 4-4 C.c. Mixtures of quinine sulphate with the respective sulphates of cinchonidine and hydroquinine were tested in the presence of two molecular proportions of inorganic chloride. It was then found that the presence of the latter rendered the test much less delicate, for the addi- tion of 5 per cent, of hydroquinine sulphate only caused an increase of about 0'4 C.c. in the amount of ammonia required, whereas had the inorganic chloride been absent it would have caused an increase of 1*6 C.c. Unfortunately, this decreased sensitiveness of the test still persists when both inorganic sulphate and chloride are present in such proportions that the effect of one neutralises that of the other. Thus, 1 gramme of pure quinine sulphate was tested according to the French method, but with the addition of one molecular proportion of potassium sulphate and two of sodium chloride. It then required 4'4 C.c. of ammonia; that is, the same amount that would have been used had the inorganic salts been absent. The experiment was then repeated, but with the use of a quinine sulphate mixture containing 5 per cent, of hydro- quinine sulphate, when 4'9 C.c. of ammonia were required, svhereas, as previously shown, 6‘0 C.c. would have been re- quired had the inorganic salts been absent. Results precisely similar to the above were obtained when bromides were substituted for chlorides. The conclusion arrived at is, therefore, that the ammonia test cannot be satisfactorily adapted to estimate the purity of the haloid salts of quinine. Optical Rotation of Quinine Salts. The new edition of the French Pharmacopoeia gives values for the optical rotation of the various quinine salts, and this factor certainly affords a good means of detecting the presence of cinchonidine or quimdine In commercial quinine salts. The present author, however, is unable to confirm the correct- ness of these values as given by the French Pharmacopoeia. This work states that a 1 per cent, solution of anhydrous quinine sulphate in dilute sulphuric acid should have [u]d —243-5° at 15°, whilst it was found that the pure salt, when examined as directed by the French Pharmacopoeia, yields a lower result, namely [a]D —235-0°. In contradistinc- tion to this, the rotation of quinine hydrochloride has been ascertained by the present author to be higher than the value given by the French Pharmacopoeia for this salt—namely, [<x]d—155-8° instead of [a]j—147-8°. The values now ob- tained for the rotations of the sulphate and hydrochloride respectively are, however, in harmony with each other, for if the rotation of the latter salt be determined in presence of an excess of sulphuric acid, and the result calculated for](https://iiif.wellcomecollection.org/image/b22425408_0013.jp2/full/800%2C/0/default.jpg)
