Medium: water;500mL.

Apparatus 1: 100rpm.

Time: 45minutes.

Procedure— Filter a portion of about 20mLof the solution under test.Transfer about 5mLof the eluant into a small test tube,and add 250µLof 0.01Msodium sulfate internal standard solution.Evaporate until dry using a vacuum centrifuge.Add 10.0µLof water to the precipitate and place on a vortex mixer until all solid material is dissolved.Transfer this solution to a capillary tube,place it in a Raman spectrometer,and obtain the Raman spectrum using suitable instrumental conditions (see Spectrophotometry and Light-scattering á851ñ).Integrate the Raman intensity,applying baseline corrections,between 660cm-1and 720cm-1.Divide this result by the integrated intensity between 966cm-1and 994cm-1.Determine the amount of C18H34N2O6Sdissolved in comparison with an aqueous Standard solution having a known concentration of USP Lincomycin Hydrochloride RS.

Tolerances— Not less than 75%(Q)of the labeled amount of C18H34N2O6Sis dissolved in 45minutes.

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

Assay preparation— Remove,as completely as possible,the contents of not less than 10Capsules,taking care to prevent capsule shell fragments from being combined with the capsule contents and to remove any shell fragments from the contents.Weigh and mix the combined contents,and transfer an accurately weighed portion of the powder,equivalent to about 50mg of lincomycin,to a suitable container.Add 50.0mLof Mobile phase,and shake by mechanical means for 5minutes.Use the solution thus obtained as the Assay preparation.

Procedure— Proceed as directed for Procedurein the Assayunder Lincomycin Hydrochloride.Calculate the quantity,in mg,of lincomycin (C18H34N2O6S)in the portion of Capsule contents taken by the formula: in which the terms are as defined therein.