Revision of USP <831> Refractive Index

Recommendation

20/21 September 2022

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Dealing with different compendial methods

In the current Pharmacopeial Forum, PF 47(3), a proposal of USP Chapter <831> Refractive Index has been published for comments.

The proposal is based on the version of the chapter official prior to 2013. According to the USP, the previous proposal in PF 46(4) has been canceled, and the text has been revised to address comments received.

Besides minor editorial changes to update the chapter to the current USP style, the revisions to the chapter include the following:

• Add specification for an apparatus that provides a means of operation at the prescribed temperature with readings to at least ±0.1°.
• Add operational qualification requirements for accuracy that state the measurement of a certified reference material should agree with the stated certified value within the limits of the expanded uncertainty of the reference material added to the performance specification of the instrument.
• Clarify the performance qualification requirements.
• Remove the three replicate measurements of the sample from the Measurement Procedure section that was previously proposed in PF 46(4).

The deadline for submitting comments is July 31, 2021.

The draft chapter USP <831> Refractive Index can be viewed here. (Please note: a one-time registration is required to access the Pharmacopeial Forum.)