Methylbenzethonium Chloride Ointment
» Methylbenzethonium Chloride Ointment contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of methylbenzethonium chloride (C28H44ClNO2·H2O).
Packaging and storage
Preserve in collapsible tubes or in tight containers.
Identification
Suspend about 0.5 g of Ointment in 10 mL of water, add 0.1 g of sodium carbonate, 1 mL of bromophenol blue TS, and 10 mL of chloroform, and shake: the chloroform layer is blue.
pH 791:
between 5.0 and 7.0, in a dispersion of it in carbon dioxide-free water (1 in 100).
Assay
0.0001 N Docusate sodium
Prepare as directed for 0.0001 N Docusate sodium in the Assay under Methylbenzethonium Chloride Lotion.
Procedure
Transfer an accurately weighed portion of Ointment, equivalent to about 0.5 mg of methylbenzethonium chloride, to a glass-stoppered, 50-mL cylinder, and proceed as directed in the Assay under Methylbenzethonium Chloride Lotion, beginning with Add 5 mL of chloroform.
Auxiliary Information
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USP32NF27 Page 2938
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