Revision of USP Chapter <621> Chromatography Concerning Signal-to-Noise Ratio

Just recently your could read  that the EDQM has published a press release stating that another revision of Ph. Eur. Chapter 2.2.46. Chromatographic separation techniques is planned. This revision will be included in Supplement 11.3 (to be published in July 2023 and implemented on 01 January 2024). This change is about the calculation of the signal-to-noise (S/N) ratio.

The USP has now published a Notice of Intent to Revise dated 06 January 2023. It states that the Chemical Analysis Expert Committee intends to revise the USP General Chapter <621> Chromatography for the same reason.

The following changes to the Signal-to-noise ratio subsection under "Definitions" are planned:

• "In the definition of H, the baseline would be extrapolated over a distance of at least 5 times the width at half-height
• The noise would be determined after the injection of a blank over a distance of at least 5 times the width at half-height of the peak in the chromatogram obtained with the prescribed reference solution and, if possible, situated equally around the place where this peak would be found.
• The last paragraph in the subsection (starting with “If a baseline of 20…”) would be deleted."

According to the statement, the revision to General Chapter <621> will be published as a Revision Bulletin on 24 March 2023.