BRIEFING

 〈313〉 Molecular Weight and Polymer Chain Length Determination for Polypropylene Glycol Fatty Ethers. This proposal is based on the version of the chapter official as of August 1, 2023.

 Method 1 in this chapter uses polypropylene glycol (PPG) standards as molecular weight calibrants, and footnote 1 mentions suitable PPG standards available on the market. However, the current footnote 1 is no longer valid, as the referenced PPG standard supplier information is no longer accurate. To enhance user convenience and standardization, USP is developing six USP PPG Reference Standards (RSs): 

• USP Polypropylene Glycol for Molecular Weight Determination 192 RS

• USP Polypropylene Glycol for Molecular Weight Determination 450 RS

• USP Polypropylene Glycol for Molecular Weight Determination 790 RS

• USP Polypropylene Glycol for Molecular Weight Determination 1000 RS

• USP Polypropylene Glycol for Molecular Weight Determination 3000 RS

• USP Polypropylene Glycol for Molecular Weight Determination 4000 RS

  The range of the RSs is selected to cover the molecular weights of the suitable substances in this chapter. USP is proposing to incorporate these RSs into Method 1  and list them in the USP Reference Standards section of the chapter.

 USP is seeking stakeholder input on using these calibrant RSs.

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

 (EXCC: P. Zhang)

 Case ID—SUB-2903