1. Alcohol (Ethanol/Ethyl Alcohol)
(Note: This is a condensed version. Reference should be made to the original, and any supplements, for full current testing details.)
| (a) | Definition: | Contains not less than 94.9% v/v (at 15.56°C), or 92.3% w/w, and not more than 96.0% v/v or w/w of ethanol. |
| (b) | Identification: | (1) Mix 5 drops
in a small beaker with 1 ml of potassium permanganate solution (1 in 100)
and 5 drops of 2N sulphuric acid, and immediately cover the beaker with
a filter paper moistened with a recently-prepared solution of 0.1 g of sodium
nitroferricyanide and 0.25 g of piperazine in 5 ml of water. An intense
blue color is produced on the filter paper, and the color fades after a
few minutes. (2) To 5 ml of a 1 in 10 solution, add 1 ml of 1.0 N sodium hydroxide, then slowly (over a period of 3 minutes), add 2 ml of 0.1 N Iodine. The odor of iodoform should develop, and a yellow precipitate should form within 30 minutes. |
| (c) | Specific gravity: | Between 0.812 and 0.816 at 15.56°C |
| (d) | Acidity: | To 50 ml of alcohol in a glass-stoppered flask, add 50 ml of recently-boiled water. Add phenolphthalein TS, and titrate with 0.02 N sodium hydroxide to a pink color that persists for 30 seconds. Not more than 0.9 ml of 0.02 N sodium hydroxide should be required for the neutralization. |
| (e) | Limit of non-volatile residue: | Evaporate 40 ml in a tared dish on a waterbath, and dry at 105°C for 1 hour. The weight of the residue should not exceed 1 mg. |
| (f) | Water-insoluble substances: | When diluted with an equal volume of water, the mixture should be clear, and remain clear for 10 minutes after cooling to 10°C. |
| (g) | Aldehydes and other foreign substances: | Place 20 ml in a thoroughly-cleaned glass-stoppered cylinder, cool to about 15°C, and add 0.1 ml of 0.1 N potassium permanganate. Note the precise time, and mix immediately by inverting the cylinder and allow it to stand at 15°C. The pink color should not completely disappear within 5 minutes. |
| (h) | Amyl alcohol and non-volatile carbonizable substances, etc.: | When 25 ml is allowed to evaporate spontaneously from a porcelain dish, (protected from dust), until the surface of the dish is barely moist, no red or brown color should be produced immediately on addition of a few drops of sulphuric acid. |
| (i) | Fusel-oil constituents: | When a piece of clean, odorless, absorbent paper is wetted with a mixture of 10 ml of alcohol, 5 ml of water and 1 ml of glycerine, which is then allowed to evaporate spontaneously, no foreign odor should be detectable as the last traces of the mixture evaporate. |
| (j) | Limit of acetone and isopropyl alcohol: | To 1 ml of alcohol, add 1 ml of water, 1 ml of saturated solution of dibasic sodium phosphate and 3 ml of a saturated solution of potassium permanganate. Warm the mixture to 45 - 50°C and allow to stand until the permanganate color is discharged. Then add 3 ml of 2.5 N sodium hydroxide, and filter through a sintered-glass filter. Then prepare a control by mixing 1 ml of the saturated dibasic sodium phosphate solution, 3 ml of 2.5 N sodium hydroxide, 80 micrograms of acetone and 5 ml of water. To each solution add 1 ml of 1 in 100 furfural solution, allow to stand for 10 minutes, then to 1 ml of each solution add 3 ml of hydrochloric acid. Any pink color produced in the test solution should not be more intense than that in the control. (Revised in 8th Supplement, 1998.) |
| (k) | Methanol: | To 1 drop of alcohol, add 1 drop of water, 1 drop of a 1 in 20 solution of phosphoric acid and 1 drop of a 1 in 20 solution of potassium permanganate. Mix and allow to stand for 1 minute, then add drops of a 1 in 20 solution of sodium bisulphite until the permanganate color is discharged. If a brown color remains, add 1 drop of the solution of phosphoric acid. To the colorless solution add 5 ml of freshly-prepared chromotropic acid T.S., and heat on a waterbath at 60°C for 10 minutes. No violet color should appear. |
2. Dehydrated Alcohol
| (a) | Definition: | Contains not less than 99.5% v/v (at 15.56°C) or 99.2% w/w of ethanol. |
| (b) | Identification: | (1) Mix 5 drops
in a small beaker with 1 ml of potassium permanganate solution (1 in 100)
and 5 drops of 2N sulphuric acid, and immediately cover the beaker with
a filter paper moistened with a recently-prepared solution of 0.1 g of sodium
nitroferricyanide and 0.25 g of piperazine in 5 ml of water. An intense
blue color is produced on the filter paper, and the color fades after a
few minutes. (2) To 5 ml of a 1 in 10 solution, add 1 ml of 1.0 N sodium hydroxide, then slowly (over a period of 3 minutes), add 2 ml of 0.1 N Iodine. The odor of iodoform should develop, and a yellow precipitate should form within 30 minutes. |
| (c) | Specific gravity: | Not more than 0.7964 at 15.56°C. |
| (d) | Acidity: | Complies with the requirements for "Alcohol." |
| (e) | Limit of non-volatile residue: | Complies with the requirements for "Alcohol." |
| (f) | Water-insoluble substances: | Complies with the requirements for "Alcohol." |
| (g) | Aldehydes and other foreign organic substances: | Complies with the requirements for "Alcohol." |
| (h) | Amyl alcohol and non-volatile, carbonizable substances: | Complies with the requirements for "Alcohol." |
| (i) | Limit of acetone and isopropyl alcohol: | Complies with the requirements for "Alcohol." |
| (j) | Methanol: | Complies with the requirements for "Alcohol." |
| (k) | Ultraviolet absorbence: | Record the ultraviolet absorbence between 340 nm and 235 nm in a 1 cm cell, with water in a matched cell for a reference beam. The absorbence should not be more than 0.08 at 240 nm and 0.02 at 270 to 350 nm, and the curve drawn through these points should be smooth. (Revised in the 8th Supplement, 1998.) |