Alcohol (Alcool, Spiritus vini rectificatus, Alcool etilico)
(Note: This is translated from the Italian original, to which reference should be made for authenticity.
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1.
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Definition: | Contains not less than 950 ml per litre (95% v/v) and not more than 96.5 ml per litre (96.5% v/v) of ethanol, (corresponding to a weight range of 923 grams to 947 grams per kg). |
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2.
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Characteristics: | A colorless, mobile, transparent, volatile liquid, with a characteristic, pleasant odor, and a burning taste. It is flammable, and burns with a blue flame. |
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3.
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Solubility: | Miscible with water, ether, chloroform and with glycerol. |
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4.
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Specific Gravity: | Between 0.8125 and 0.8055. |
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5.
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Boiling-point range: |
From 77°C to 78.5°C. |
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6.
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Identification: |
(A) Dilute 1 ml of alcohol to 100 ml with water. Then, to 5 ml of this solution, add 3 ml of dilute sodium hydroxide and then slowly add 2 ml of 0.1 N iodine solution. There should be an odor of iodoform, and a yellow precipitate. (B) When heated with sulphuric acid and potassium dichromate solution, there should be a green coloration and an odor of acetaldehyde. (C) Mix 0.1 ml in a 10 ml beaker with 1 ml of an aqueous solution of potassium permanganate (10 g/li) and 0.2 ml of dilute sulphuric acid. Cover the beaker with a filter paper soaked in a fresh solution containing 0.1 g of sodium nitroprusside and 0.5 g of piperazine in 5 ml of water. An intense blue color should form on the filter paper, and it should fade in a few minutes. |
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7.
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Test for Purity: | |
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(a)
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Appearance: | There should be no color or turbidity in the alcohol, using standard tests. When diluted 1:20, it should remain clear for at least 5 minutes. |
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(b)
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Acidity/alkalinity: | To 50 ml of alcohol, add 5 ml of water and 0.1 ml of phenolphthalein solution. The mixture should be colorless. If 0.2 ml of 0.01 N sodium hydroxide are added, the solution should become red. If 0.3 ml of 0.01 N hydrochloric acid are added, the solution should become colorless. If 0.2 ml of methyl red solution are added, the solution should become reddish or orange. |
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(c)
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Acetone: | Dilute 1 ml of alcohol distillate (obtained from the boiling-point test) with 9 ml of water in a test tube, and add 0.01 g of finely-powdered vanillin and approximately 1.5 g of potassium hydroxide in tablet form. Heat and agitate in a water bath for 15 minutes. It should form a yellow layer on the potassium hydroxide, which does not turn orange or red. |
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(d)
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Methanol: | Take 0.4 ml of alcohol distillate (obtained from the boiling-point test), add 5 ml of 0.1 N potassium permanganate, 0.2 ml of sulphuric acid and then after at least 2 minutes, add 1 ml of oxalic acid solution and 1 ml of sulphuric acid. To this colorless mixture, add 5 ml of decolorized fuchsin solution and hold at a temperature of 15 - 30°C for 20 minutes. No blue-violet or red coloration should be produced. |
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(e)
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Aldehydes: | Mix 10 ml of alcohol with 1 ml of m-phenylenediamine hydrochloride solution. When viewed from the top, it should not develop as intense a yellow color as is formed in a mixture of 0.4 ml of tropaeolin oo (diphenylamine orange) solution in 100 ml of water. |
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(f)
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Ketones, isopropanol and tertiary butanol: | Dilute 1 ml of alcohol with 3 ml of water, and add 10 ml of mercuric sulphate solution. Heat in a boiling-water bath. There should not be any precipitate formed within 3 minutes. |
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(g)
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Furfural: | To 10 ml of alcohol, add 1 ml of glacial acetic acid and 0.5 mg of aniline. The mixture should not develop a reddish color within 5 minutes. |
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(h)
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Amyl alcohol and carbonizable substances of low volatility: | When 25 ml of alcohol is allowed to evaporate spontaneously, from a porcelain dish, (protected from dust), until the surface of the dish is barely moist, there should be no foreign odor (of fusels), and the addition of 1 ml of sulphuric acid should not produce a red or dark coloration. |
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(i)
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Oily and resinous substances: | The alcohol mixed with water in any proportion should remain clear, when cooled to 5 - 10°C for 30 minutes. |
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(j)
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U.V. Absorbance: | Record the U.V. absorbance between 235 and 275 nm, in a 5 cm cell, using water in a matched cell for reference. There should not be any absorbance greater than 0.35 at 240 nm, or 0.20 between 250 and 260 nm, or 0.15 at 270 nm. |
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(k)
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Foreign organic substances: | Add 20 ml of alcohol to a thoroughly cleaned, glass-stoppered cylinder, and cool to 15°C. Then add 0.1 ml of a 0.1N potassium permanganate solution, and note the exact time. Then mix by inverting the cylinder and allow it to stand at 15°C for 5 minutes. The reddish coloration should disappear completely in that time. |
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(l)
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Tannins: | If 5 drops of dilute ammonia are added to 3 ml of alcohol, the mixture should remain colorless. |
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(m)
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Denatured alcohol: | 10 ml of alcohol which have been acidified with dilute sulphuric acid, are allowed to evaporate in a water bath. The residue, when treated with potassium hydroxide solution, should not give any pyridine-like odor. |
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(n)
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Chlorine: | 4 ml of alcohol diluted to 15 ml with water should comply with the standard test for chlorine (at the 1.5 ppm level) using for comparison 1 ml of a 5 ppm solution of chlorine diluted with water to 15 ml. |
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(o)
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Heavy metals:
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50 ml of alcohol are evaporated in a water bath to 5 ml, and diluted to 25 ml with water. 12 ml of the solution should comply with the standard test for heavy metals (at the 0.3 ppm level), using for comparison, a mixture of 5 ml of a 1 ppm solution of lead, and 5 ml of water. |
| (p) | Residue on evaporation: | If 100 ml of alcohol are evaporated in a water bath, and the dish is dried at 100 - 105°C, the weight of the residue should not exceed 2 mg (or 0.002 percent). |