Benzethonium Chloride Tincture
»Benzethonium Chloride Tincture contains,in each 100mL,not less than 190mg and not more than 210mg of C27H42ClNO2.
| Benzethonium Chloride | 2g |
| Alcohol | 685mL |
| Acetone | 100mL |
| Purified Water,a sufficient quantity to make |
1000mL |
Dissolve the Benzethonium Chloride in a mixture of the Alcohol and the Acetone.Add sufficient Purified Water to make 1000mL.
NOTE—Benzethonium Chloride Tincture may be colored by the addition of any suitable color or combination of colors certified by the FDAfor use in drugs.
Packaging and storage—
Preserve in tight,light-resistant containers.
Identification—
The residue obtained by evaporating 50mLon a steam bath responds to Identificationtests Aand Bunder Benzethonium Chloride.
Specific gravity á841ñ:
between 0.868and 0.876.
Alcohol and acetone content—
To a 100-mLvolumetric flask transfer 20.0mLof Benzethonium Chloride Tincture and 5.0mLof methanol as the internal standard,dilute with water to volume,and mix.Similarly prepare four 100-mLstandard solutions in water,each containing 5.0mLof methanol as the internal standard,and individually containing,respectively,11.0mLof dehydrated alcohol,14.0mLof dehydrated alcohol,1.7mLof acetone,and 2.2mLof acetone.Inject 0.8µLof the solution containing the substance under test into a suitable gas chromatograph equipped with a flame-ionization detector,and record the chromatogram.Similarly and successively record the chromatograms for 0.8-µLinjected volumes of the four standard solutions.Under typical conditions,the instrument contains a 120-cm ×4-mm column packed with a suitable type of support,such as 80-to 100-mesh S3;the column is maintained at about 120
;the injection port and detector block temperatures are maintained at about 240;and dry helium is used as the carrier gas at a flow rate of about 90mLper minute.From the respective chromatograms obtained as described previously,calculate the ratios of peak areas for alcohol to internal standard and for acetone to internal standard.
;the injection port and detector block temperatures are maintained at about 240;and dry helium is used as the carrier gas at a flow rate of about 90mLper minute.From the respective chromatograms obtained as described previously,calculate the ratios of peak areas for alcohol to internal standard and for acetone to internal standard.
Calculate the percentage of alcohol and of acetone in the Tincture by the formula:
[A(Y-Z)+B(Z-X)]/(Y-X),
in which Aand Bare the percentage of alcohol,or of acetone,in the lower and higher standards,respectively;and X,Y,and Zare the ratios of the alcohol peak areas,or the acetone peak areas,to the internal standard peak areas for the lower standard,higher standard,and the material under test,respectively:the content of C2H5OHis between 62.0%and 68.0%,and the content of acetone (C3H6O)is between 9.0%and 11.0%.
Assay—
Transfer 50.0mLof Tincture to a 150-mLbeaker,and add,with continuous stirring,10mLof sodium tetraphenylboron solution (1in 40).Cover,and allow to stand for 16hours.Decant the supernatant into a tared sintered-glass crucible,applying vacuum filtration.Suspend the precipitate in 20mLof water,and transfer the precipitate to the crucible,washing well with water.Dry the precipitate and the crucible at 105for 1hour,cool,and weigh.The weight of the precipitate so obtained,multiplied by 0.6122,represents its equivalent of C27H42ClNO2.
for 1hour,cool,and weigh.The weight of the precipitate so obtained,multiplied by 0.6122,represents its equivalent of C27H42ClNO2.
Auxiliary Information—
Staff Liaison:Behnam Davani,Ph.D.,MBA,Senior Scientist
Expert Committee:(PA7)Pharmaceutical Analysis 7
USP28–NF23Page 228
Phone Number:1-301-816-8394