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<621> Chromatography

Type of Posting: Notice of Intent to Revise 
Posting Date:  06-Jan-2023 
Targeted Official Date: April 1, 2023, Revision Bulletin 
Expert Committee: Chemical Analysis Expert Committee 
In accordance with the Rules and Procedures of the Council of Experts, this is to provide notice that the Chemical Analysis Expert Committee intends to revise General Chapter <621> Chromatography

Based on the comments received from stakeholders, the committee considered it appropriate to introduce a change in the calculation of the signal-to-noise ratio (see Signal-to-noise ratio under Definitions). The current harmonized text directs users to calculate the noise using a portion of a blank injection equivalent to 20 times the peak width at half height. Comments received indicated that it will be challenging to meet this requirement in a considerable number of cases. To address the problem, the EDQM has recently posted an announcement that it is planning to revert to its previously official requirement to calculate the noise on a window of at least 5 times the peak width at half height 

The Expert Committee proposes to make the following changes to the Signal-to-noise ratio subsection under Definitions

  1. In the definition of H, the baseline would be extrapolated over a distance of at least 5 times the width at half-height
  2. 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.
  3. The last paragraph in the subsection (starting with “If a baseline of 20…”) would be deleted

It is anticipated that the proposed revision to General Chapter <621> will be published as a Revision Bulletin on March 24, 2023 pursuant to the Rules and Procedures of the Council of Experts.   

Should you have any questions, please contact Horacio Pappa, Senior Director (