BRIEFING

 Dimethyl Sulfoxide. This proposal is based on the version of the monograph official as of May 1, 2020. It is proposed to revise the monograph with the following changes:

1. Identification A is revised to provide the flexibility of using either 197A or 197F.

2. Identification B is replaced with the retention time agreement of the dimethylsulfoxide peak in the Sensitivity solution and the major peak in the Sample solution as described under the Organic Impurities test.

3. The note under the Assay is deleted to be consistent with the Definition and the Acceptance criteria.

4. The Organic Impurities test is replaced with a new validated gas chromatography procedure to minimize column contamination and sample carry over. The procedure was validated using the RTX-624 brand of capillary column with phase G43. The typical retention time for dimethyl sulfoxide is about 5.3 min.

5. Add USP Methylsulfonylmethane RS to the USP Reference Standards section to support the proposed Organic Impurities test.

 Additionally, minor editorial changes have been made to update the monograph to current USP style.

 Manufacturers are encouraged to share their specifications if they are different from the proposal and storage temperature conditions.

 (SM3: S. Ramakrishna)

 Correspondence Number—C211214