USP Publishes Comments Received on Chapter <320>

In its USP–NF 2027 Issue 1 Commentary, the United States Pharmacopeia (USP) addressed comments received on General Chapter <320> NMR Spectroscopy for the Determination of Degree of Hydrolysis for Polyvinyl Alcohol and Vinyl Alcohol Homopolymer, and Monomer Ratio for Vinyl Alcohol and Vinyl Acetate Copolymer.

The proposed chapter, originally published in Pharmacopeial Forum, PF 51(3), introduces a validated ¹H-NMR method for determining the degree of hydrolysis of polyvinyl alcohol and vinyl alcohol homopolymer, as well as the monomer ratio of vinyl alcohol and vinyl acetate copolymer.

The chapter is scheduled to become official on 1 February 2027 as part of USP–NF 2027 Issue 1.

The Excipient Chapters Expert Committee received comments from four commenters. USP incorporated or clarified the following points:

• The sample preparation instructions now allow greater flexibility regarding weights and volumes.
• D₂O at 4.79 ppm and 27° was added as the chemical-shift reference.
• The integration ranges were changed to approximately 3.4–4.4 ppm and 2.1–2.3 ppm to account for minor instrument-related shifts.
• “Acetate signal” was replaced by “acetyl signal”, and “supernatant” by “solution”.
• A representative spectrum was added to clarify the signal-intensity suitability requirement.
• The pulse sequence was specified as “Single pulse for proton without water suppression”.
• USP clarified that the existing requirement of not less than 11.74 tesla corresponds to a ¹H frequency of 500 MHz; a separate minimum field-strength requirement was therefore not added.

For further information, please see the USP Proposal Status/Commentary.