USP: Chapter "<621> Chromatography" published for Comments

Since the beginning of November, the updated version of the chapter "<621> Chromatography" has been available on the website of the Pharmacopeial Forum of the USP and published for comments. Comments on this draft, which is based on the previous version from October 2023, can be submitted until 31 January 2024.

The changes and updates to this chapter were mainly made in addition to minor formal adjustments in the "System Sensitivity" and "Peak Symmetry" paragraphs, both of which are assigned to the "System Suitability" section and are due to come into force in May 2025.

System Sensitivity

The new wording of the paragraph "System sensitivity" now reads in the revised version:

"For impurity tests where the procedure in a monograph specifies the use of a reporting threshold, the signal-to-noise ratio is used to define the system sensitivity. To determine the signal-to-noise ratio, a reference solution of the analyte (official substance) is injected at the concentration corresponding to the reporting threshold. The requirement is fulfilled if the limit of quantification (corresponding to a signal-to-noise ratio of 10) is equal to or lower than the reporting threshold."

What is new here is that the procedure only has to be used if a reporting threshold is specified for the impurity tests in the associated monograph.

Peak Symmetry

The paragraph "Peak Symmetry" is now presented as follows:

"Unless otherwise stated, in the Organic Impurities test, Related Substances test, or the Assay, the symmetry factor (tailing factor) of the peak in the standard solution used for quantification is 0.8-1.8. The peak symmetry requirement is waived if the determination of the %RSD is prescribed as part of the System Suitability test."

This paragraph has been supplemented by the addition that it only applies to tests for organic impurities and related substances and assays. It also indicates that this requirement is negligible if the percentage of relative standard deviation has already been described in the "System Suitability" paragraph.

The new draft of the chapter "<621> Chromatography" can be viewed and commented on the Pharmacopeial Forum website after a one-time registration.

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