» Ether contains not less than 96.0 percent and not more than 98.0 percent of C4H10O, the remainder consisting of alcohol and water.
[CautionEther is highly volatile and flammable. Its vapor, when mixed with air and ignited, may explode. ]
noteEther to be used for anesthesia must be preserved in tight containers of not more than 3-kg capacity, and is not to be used for anesthesia if it has been removed from the original container longer than 24 hours. Ether to be used for anesthesia may, however, be shipped in larger containers for repackaging in containers as directed above, provided the ether at the time of repackaging meets the requirements of the tests of this Pharmacopeia.
Packaging and storage Preserve in partly filled, tight, light-resistant containers, at a temperature not exceeding 30 remote from fire.
Labeling Where Ether is intended for anesthetic use, the label so states.
Specific gravity 841: between 0.713 and 0.716 (indicating 96.0% to 98.0% of C4H10O).
Acidity To 10 mL of water in a glass-stoppered flask, add 0.10 mL of bromothymol blue TS and 0.010 N sodium hydroxide until a blue color persists after vigorous shaking. Add 25 mL of Ether, and shake briskly to mix the two layers. If no blue color remains, titrate with 0.010 N sodium hydroxide until the blue color is restored and persists for several minutes: not more than 0.80 mL of 0.010 N sodium hydroxide is required (0.003% as CH3COOH). [noteExercise great care to avoid contamination from carbon dioxide when adding the Ether and titrating. ]
Water, Method I 921: not more than 0.5%, except where labeled as intended for anesthetic use, it contains not more than 0.2%.
Limit of nonvolatile residue Allow 50 mL to evaporate spontaneously from a tared dish, and dry at 105 for 1 hour: the weight of the residue does not exceed 1 mg (0.003%).
Aldehyde Place 20 mL in a glass-stoppered cylinder, and add 7 mL of a mixture of 1 mL of alkaline mercuric-potassium iodide TS and 17 mL of a saturated solution of sodium chloride. Insert the stopper in the cylinder, shake vigorously for 10 seconds, then set aside for 1 minute: the water layer shows no turbidity.
Limit of peroxide
Titanium tetrachloride solution Cool separately, in small beakers surrounded by crushed ice, 10 mL of 6 N hydrochloric acid and 10 mL of titanium tetrachloride. Add the titanium tetrachloride dropwise to the chilled acid. Allow the mixture to stand at ice-bath temperature until all of the yellow solid dissolves, dilute the solution with 6 N hydrochloric acid to 1000 mL, and mix.
Peroxide standard solution Pipet 25 mL of hydrogen peroxide solution into a 1000-mL volumetric flask, dilute with water to volume, and mix. Pipet 15 mL of this solution into a 1000-mL volumetric flask, dilute with water to volume, and mix. Each mL contains 0.011 mg of H2O2.
Procedure To 50 mL of Ether, in a separator, add 5.0 mL of Titanium tetrachloride solution. Shake vigorously, allow the layers to separate, and drain the lower layer into a glass-stoppered, 25-mL graduated cylinder. Dilute with water to 10.0 mL, and mix. Any yellow color in the solution does not exceed that of a solution prepared by adding 5.0 mL of Titanium tetrachloride solution and 1.0 mL of Peroxide standard solution to a glass-stoppered, 25-mL graduated cylinder, diluting with water to 10.0 mL, and mixing, the colors being determined in 1-cm cells, with a suitable spectrophotometer, at a wavelength of 410 nm. The limit is 0.3 ppm.
Standard preparation Transfer about 50 mL of anhydrous ethyl ether, previously tested for absence of hydrocarbons, as directed under Procedure, to a 100-mL volumetric flask. Add 0.20 mL of pentane, dilute with the same anhydrous ethyl ether to volume, and mix.
Apparatus Under typical conditions, a gas chromatograph (see Chromatography 621) is equipped with a flame-ionization detector, and contains a 3.7-m × 2-mm (ID) stainless steel column packed with 30% phase G22 on 30- to 60-mesh support S1C. The injector port, column, and detector are maintained at temperatures of about 230, 80, and 250, respectively, nitrogen being used as the carrier gas at a flow rate of about 30 mL per minute.
Procedure Inject 1 µL of Standard preparation and Ether, respectively, into the apparatus, and measure the total area under the hydrocarbon peaks (under typical conditions the retention times are about 2.3 minutes for isopentane, 2.7 minutes for pentane, and 4.3 minutes for 2-methylpentane) in the Ether. The total area of the hydrocarbon peaks does not exceed that of the peak for pentane in the Standard preparation (0.2%).