Revision of USP <857> Ultraviolet-Visible Spectroscopy and <1857> Ultraviolet-Visible Spectroscopy - Theory and Practice

In the Pharmacopeial Forum, PF 47(4), proposals of USP Chapters <857> Ultraviolet-Visible Spectroscopy and <1857> Ultraviolet-Visible Spectroscopy—Theory and Practice have been published for comments. The deadline for submitting comments for both proposals is September 30, 2021.

A Chapter numbered below 1000 becomes applicable and compendially required respect were it is referenced in a monograph or another applicable General Chapter numbered below 1000 or in General Notices. General Chapters numbered 1000 to 1999 are for informational purposes only. They are considered interpretive and are intended to provide information on, give definition to, or describe a particular subject.

<857> Ultraviolet-Visible Spectroscopy

This proposal is based on the version of the monograph official as of January 1, 2020. Besides minor editorial changes to update the chapter to the current USP style, the revisions to the chapter include the following:

• Clarify that the scope of the chapter does not apply to multichannel plate readers.
• Remove the Xe line reference in Table 2 for control of wavelength by atomic line spectra.
• Remove the Control of Photometric Response section as demonstrating absorbance accuracy over its intended operational range assures proper photometric response.
• Revise for clarity the requirements and procedures for Control of Absorbance, including procedures for absorbance accuracy and precision.
• Clarify the equation in Procedure A for the Estimation of the Limit of Stray Light as determined from the differential absorbance spectrum.
• Replace the term “cell” with “cuvette” throughout.

Further revisions to include appropriate standards for chromatographic detectors and multichannel plate readers are under discussion and may be proposed at a later date.

The draft chapter <857> Ultraviolet-Visible Spectroscopy can be viewed here. (Please note: a one-time registration is required to access the Pharmacopeial Forum.)

<1857> Ultraviolet-Visible Spectroscopy—Theory and Practice

This proposal is based on the version of the chapter official as of May 1, 2015. According to the USP, the revisions to the chapter include:

• Reorder sections of the chapter to improve upon the flow of concepts and align concepts with Ultraviolet-Visible Spectroscopy <857>, which also has proposed revisions in this issue of PF.
• Rename the Instrumentation section as "UV Spectrometers" and expand it to include additional optical configurations, a discussion of the impact on spectral bandwidth on signal-to-noise ratios, and additional discussions on stray light.
• Include new sections on Temperature Coefficients and Effects and Solvent Selection Effects with regard to impact on analysis.
• Remove the section on Derivative Spectroscopy.
• Replace the term "spectrophotometry" with "spectroscopy" throughout.
• Replace the term “cell” with “cuvette” throughout.

The draft chapter <1857> Ultraviolet-Visible Spectroscopy—Theory and Practice is available following this link.