Methacholine Chloride
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C8H18ClNO2 195.69

1-Propanaminium, 2-(acetyloxy)-N,N,N-trimethyl-, chloride, (±)-.
(±)-(2-Hydroxypropyl)trimethylammonium chloride acetate [62-51-1].
» Methacholine Chloride, dried at 105 for 4 hours, contains not less than 98.0 percent and not more than 101.0 percent of C8H18ClNO2.
Packaging and storage— Preserve in tight containers.
A: Dissolve about 100 mg in about 2 mL of water on a watch glass, and add 3 mL of platinic chloride TS: small rhombohedric plates are formed, which melt between 220 and 225 (see Melting Range or Temperature 741) (distinction from acetylcholine chloride, which forms needles radiating from a central point, and from choline chloride, which forms no crystals).
B: To 1 mL of a solution (1 in 10) add 1 mL of alcohol and 1 mL of sulfuric acid, and heat gently: the odor of ethyl acetate is perceptible.
C: To 5 mL of a solution (1 in 10) add 2 g of potassium hydroxide and heat gently: the odor of trimethylamine is perceptible.
D: A solution (1 in 50) responds to the tests for Chloride 191.
Melting range 741 Dissolve about 100 mg in 2 to 3 mL of chloroform in a small beaker. Heat at 110 for 1 hour. While the test specimen is still hot, quickly powder the dry residue with a glass rod, and transfer to a melting point tube in the usual manner. Determine the melting range without delay. It melts between 170 and 173.
Loss on drying 731 Dry it at 105 for 4 hours: it loses not more than 1.5% of its weight.
Residue on ignition 281: not more than 0.1%.
Acetylcholine chloride— To 2 mL of a solution (1 in 10) add 3 mL of a solution of sodium perchlorate (1 in 5), shake, and immerse in ice water for 5 minutes: no precipitate is formed.
Assay— Transfer to a conical flask about 400 mg of Methacholine Chloride, previously dried and accurately weighed (because it is very hygroscopic, store the dried material in a vacuum desiccator), dissolve it in 50 mL of glacial acetic acid, add 10 mL of mercuric acetate TS and 1 drop of crystal violet TS, and titrate with 0.1 N perchloric acid VS to a blue-green endpoint. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 19.57 mg of C8H18ClNO2.
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