1961 年 81 巻 2 号 p. 155-159
A solution of morphine colors red when heated with 1-nitroso-2-naphthol in dil. nitric acid but the color is unstable (Reaction I). This coloration is not produced by codeine, thebaine, narcotine, and papaverine. The reaction of morphine with chloramine-T in dil. hydrochloric acid solution and addition of 4-aminoantipyrine into this solution results in red coloration (Reaction II ). This color is comparatively stable but codeine also exhibits this coloration and it must be separated from the opium alkaloids for separatory determination. Separation of codeine can be effected by extraction with chloroform in sodium hydroxide alkalinity. Limit of detection by a spot reaction is 5γ/0.05cc. by the Reaction I and 10γ/0.05cc. by the Reaction II. Determination of morphine by the Reaction II is carried out as follows: One cc. of the test solution (morphine, 150-600γ/cc.) and 1cc. of N hydrochloric acid are placed in a 10cc. measuring flask and the flask is immersed in water of 10-15° for 5minutes. The reagents, 0.4% chloramine-T solution (A) and 4% aminopyrine solution (B) are also similarly treated. One cc. of (A) is added to the test solution, maintained at the same temperature for 3minutes, 0.5cc. of (B) is added, and the mixture is maintained at the same temperature for 5minutes. To this mixture, 1cc. of 1.5% potassium ferrocyanate is added, flask is taken out, stood for 3minutes, 1cc. of 5% solution of 4-aminoantipyrine is added, followed by 1.5cc. of 5% ammonia water within 3minutes, and the mixture is diluted to 10cc. with water. This is shaken with 2cc. of chloroform (shaking vigorously about 100 times) and the mixture is cen-trifuged. Optical density of its aqueous layer at 505mμ is measured 20-30minutes after coloration. Blank test is carried out with 1cc. of water in place of the test solution.