DETECTION OF ETHYL ALCOHOL

7. DETECTION OF ETHYL ALCOHOL

Alcohol has been used frequently as an adulterant, since it is a cheap and available diluent for essential oils. The presence of ethyl alcohol as an adulterant may be readily detected by several simple tests.
Procedure I: Determine accurately the refractive index and specific gravity of the oil. Then shake thoroughly an equal volume of oil and saturated salt solution in a separatory funnel. Permit the oil to separate completely and determine the refractive index and specific gravity of this washed oil. These should not differ materially from those of the original oil. An approximation of the amount of added alcohol may be obtained from a consideration of these values.
This procedure is not specific for alcohol and will detect other watersoluble adulterants.
Procedure II: Place 50 cc. of the oil (previously dried with anhydrous sodium sulfate) in a 100 cc. Ladenbung flask and distill slowly over an open flame. Collect and measure the distillate below 100o. Since most constituents of essential oils boil much above 100o, unadulterated oils generally show no distillate at this temperature. However, if a distillate is obtained dilute to 10 cc. with distilled water. Test a 5 cc. portion for ethyl alcohol by the iodoform test and the residual 5 cc. portion by the ethyl benzoate test.
Iodoform Test: To 5 cc. of the diluted distillate add 10 drops of a 10% sodium hydroxide solution and suflicient iodinepotassium iodide solution drop by drop until a faint, permanent yellow color is obtained, indicating an excess of iodine. Allow the test tube to stand undisturbed for 5 min. The formation of yellow, flat, hexagonal crystals with tiie peculiar odor of iodoform indicates a positive reaction. If no positive result is obtained, heat the test tube to 60 for 1 min. in a beaker of water and permit the mixture to stand for 1 hr.
The iodine-potassium iodide solution is prepared by dissolving 2 g. of potassium iodide in 8 cc. of distilled water and adding 1 g. of iodine; stir until solution is complete.
Ethyl Benzoate Test: To 5 cc. of the dilute distillate add 5 drops of benzoyl chloride and 2 c. of a 10% sodium hydroxide solution. Warm on a steam bath. The fruity odor of ethyl benzoate indicates the presence of ethyl alcohol.
The iodoform test will give a positive reaction with any compound contening a CH3CO- group united to either a carbon or a hydrogen atom, or to any chemical which is oxidized under the conditions of the test to a compound having such a structure. In particular, acetone will give a positive iodoform test. In the ethyl benzoate test, all low boiling aliphatic alcohols will give fruity odors. However, only ethyl alcohol will give positive results with both the iodoform and ethyl benzoate testp.
The presence of ethyl alcohol materially lowers the flash point of most essential oils. There exist insufficient published data on the normal limits of the flash points of the unadulterated oils to draw valid conclusions from the results of flash-point determinations.
Oils containing relatively large amounts of alcohol will form milky emulsions with water. Use of this fact may be made for a quick test.

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