USP Chapter 621 for Chromatography: Common Questions - Tip304

OBJECTIVE or GOAL

Answers to a few commonly asked questions about changes to USP Chapter 621 for Chromatography.

ENVIRONMENT

• Empower
• Tip of the Week #304

PROCEDURE

QUESTION 1
With regard to the half-height multiplier changing from 5 to 20, what if I do not have enough baseline or there are interfering peaks? 
A: Per USP Chapter 621, if a baseline of 20 times the width at half-height is not obtainable because of peaks due to the solvents or reagents, or arising from the mobile phase or the sample matrix, or stemming from the gas chromatographic temperature program, a baseline of at least 5 times the width at half-height is permitted. 

QUESTION 2
What is the impact on equipment qualification, especially regarding the signal-to-noise (s/n) change as a requirement of the qualification process? 
A: There are a variety of approaches to measuring signal-to-noise, especially the noise portion of the equation. For chromatographic system qualification, Waters does not believe that the upcoming USP changes in Chapter 621 have an impact. The USP definition of noise is intended specifically for USP monograph procedures and does not dictate the approach for other types of procedures, nor for chromatographic system qualification. The s/n specification defined for a given system and used in the Waters SystemsQT for Systems is based on factory specifications and testing using the defined s/n measurements and chromatographic conditions. This data is used to define the acceptance criteria for our SystemsQT for Systems protocols. Changing the approach to measuring s/n and redefining the specification and acceptance criteria may result in slightly different numbers; however, this does not in any way negate the validity of the current s/n calculation or affect the performance of the system.

QUESTION 3
Is Waters developing a hotfix for older versions of Empower or any type of tool to automatically update Empower to comply with these changes? 
A: There are no plans to provide hotfixes for these changes because these types of changes are not conducive to a simple turnkey solution in Empower. It may be possible for your local Professional Services teams to assist in evaluating the impact of these changes to your organization and to assist with necessary updates to Empower methods or other types of configuration changes. Please contact your local Waters representative if you want to pursue this.

QUESTION 4
Has the date for the change of USP Chapter 621 been delayed?
A: The changes go into effect on 1 December 2022. What has been delayed are the subsections for System Sensitivity and Peak Symmetry. 

QUESTION 5
Will I need to revalidate my methods when these changes take place, and will this affect acceptance criteria?
A: We think acceptance criteria would remain the same (i.e., baseline resolution between adjacent peaks is classically defined at >= 1.5). We do not believe the methods will need revalidation; however, we recommend that you contact the USP with this question.