Methylene Chloride
CH2Cl2 84.93

Methane,dichloro-.
Dichloromethane [75-09-2].
»Methylene Chloride contains not less than 99.0percent of CH2Cl2.
[Caution—Perform all steps involving evaporation of methylene chloride in a well-ventilated fume hood. ]
Packaging and storage — Preserve in tight containers.
Identification— Place about 5mLinto a glass-stoppered,10-mLconical flask,and shake for several minutes.Remove the stopper,quickly withdraw a portion of the vapor into a 50-mLsyringe that is not fitted with a needle,and inject the vapor into a suitable evacuated gas cell:the IRabsorption spectrum of the vapor shows strong doublet peaks at 7.8µm and 7.9µm and at 13.2µm and 13.4µm,and relatively few minor peaks.
Specific gravity á841ñ: between 1.318and 1.322.
Water,Method Iá921ñ: not more than 0.02%.
Limit of hydrogen chloride— Into each of 2glass-stoppered,50-mLcolor-comparison cylinders having an internal diameter of 20mm place 10mLof water,2drops of phenolphthalein TS,and sufficient 0.010Nsodium hydroxide to produce a pink color that persists after vigorous shaking for 30seconds,and is of equal intensity in each cylinder.[NOTE—In the following steps,take special care to avoid contamination with carbon dioxide.]Into one of the cylinders place 20.0mLof Methylene Chloride and 0.70mLof 0.010Nsodium hydroxide,and shake again.The pink color in the test cylinder is at least as intense as that in the comparison cylinder,and the color persists for not less than 15minutes (0.001%).
Limit of nonvolatile residue— Evaporate 50g in a platinum or porcelain dish on a steam bath,and dry at 105for 30minutes:the weight of the residue does not exceed 1mg (0.002%).
Heavy metals,Method Iá231ñ— Evaporate 15mL(20g)in a glass evaporating dish on a steam bath to dryness.Cool,add 2mLof hydrochloric acid,and slowly evaporate again on a steam bath to dryness.Dissolve the residue in 1mLof 1Nacetic acid,add 24mLof water,and mix:the limit is 1ppm.
Free chlorine— To 10mLadd 10mLof water and 0.1mLof potassium iodide TS,shake for 2minutes,and allow the liquids to separate:the lower layer does not show a violet tint.
Assay—
Chromatographic system— Under typical conditions,the instrument is equipped with a thermal conductivity detector,and contains a 4-mm ×1.8-m column packed with 15%liquid phase G18on 30-to 60-mesh S1Cunsilanized support.The temperatures of the column,the injection port,and the detector are maintained at 60,200,and 250,respectively;and helium is used as the carrier gas,at a flow rate of about 20mLper minute.
System suitability— Chromatograph five 1-µLinjections of a mixture of 3mLof methylene chloride with 7mLof chloroform.The relative standard deviation of the peak response ratio does not exceed 2%,the resolution factor is not less than 4.0,and the tailing factor is not more than 1.4(see Chromatography á621ñ).
Procedure— Inject about 1µLof Methylene Chloride,and determine the peak responses by any convenient means.The order of elution is amylenes (5or 6peaks),if present,and then methylene chloride.Calculate the percentage of CH2Cl2in the Methylene Chloride by dividing the response due to the methylene chloride by the sum of the responses for all the peaks and multiplying by 100.
Auxiliary Information— Staff Liaison:Karen A Russo,Ph.D.,Scientist
Expert Committee:(EMC)Excipients:Monograph Content
USP28–NF23Page 3037
Phone Number:1-301-816-8379