FORSUSPENSION PACKAGED IN SINGLE-UNIT CONTAINERS: meets the requirements.

Standard preparation— Prepare a dry mixture of 1part by weight of USP Chloramphenicol Palmitate Polymorph A RSand 9parts by weight of USP Chloramphenicol Palmitate Nonpolymorph A RS.Prepare a 1in 3mineral oil dispersion of this mixture,and place a portion of it between two sodium chloride plates,taking care not to allow air bubbles to form.

Test preparation— Place 20mLof previously mixed Oral Suspension in a 50-mLcentrifuge tube,add 20mLof water,and mix.Centrifuge,and discard the supernatant.Add 20mLof water to the residue in the centrifuge tube,mix,centrifuge,and discard the supernatant.Repeat this washing two times.Dry the residue in vacuum over silica gel for not less than 14hours.Prepare a 1in 3mineral oil dispersion of the dried residue,and place a portion of it between two sodium chloride plates,taking care not to allow air bubbles to form.

Procedure— Concomitantly record the absorption spectra of the Standard preparationand the Test preparationfrom about 11µm to about 13µm,with a suitable IRabsorption spectrophotometer,using an empty cell to set the instrument to 100percent transmittance.Adjust the cell thickness of the Standard preparationand of the Test preparationso that transmittances of 20%to 30%are obtained at 12.3µm.On each spectrum,draw a straight baseline between the absorption minima at wavelengths of about 11.3µm and 12.65µm.Draw straight lines,perpendicular to the wavelength scale,at the wavelengths of maximum absorption at about 11.65µm and 11.86µm,intersecting both the baseline and the spectrum.Determine the absorbance ratio: in which the parenthetic expressions are the differences in absorbance values obtained at the wavelengths indicated by the subscripts for the spectrum (a)and at the point of intersection of the perpendicular line with the baseline (b).The absorbance ratio of the Test preparationis greater than that of the Standard preparation,corresponding to not more than 10%of polymorph A.

Mobile phase ,Standard preparation,and Chromatographic system—Proceed as directed in the Assayunder Chloramphenicol Palmitate.

Assay preparation— Transfer an accurately measured volume of Oral Suspension,well-shaken and free from air bubbles,equivalent to about 160mg of chloramphenicol,to a 200-mLvolumetric flask containing about 20mLof methanol,add 4mLof glacial acetic acid,dilute with methanol to volume,and mix.Filter about 20mLof this solution through glass-fiber filter paper.Transfer 10.0mLof the filtrate to a 25-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.

Procedure— Proceed as directed for Procedurein the Assayunder Chloramphenicol Palmitate.Calculate the quantity,in mg,of chloramphenicol (C11H12Cl2N2O5)equivalent in each mLof Oral Suspension taken by the formula: in which Vis the volume,in mL,of Oral Suspension taken,and the other terms are as defined therein.