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Should Waters qualification products calculate s/n in the manner detailed in USP621? - WKB241191

Article number: 241191

ENVIRONMENT

  • Empower 3
  • SystemsQT
  • waters_connect

ANSWER

No. 

There are a variety of approaches to measure signal to noise, especially the noise portion of this 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 Waters qualification products 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 qualification 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 in Waters qualification products; nor does it affect the performance of the system.

Waters has no plans to update the approach used to determine S/N in the Waters qualification products.

In a scenario where S/N measurements are taken and used to subsequently determine LOD/LOQ for a pharmaceutical or other type of product using a monograph approach (or any other chromatographic procedure to which USP adherence is desired), the noise should be measured per the USP definition.

ADDITIONAL INFORMATION

  1. USP now recommends that the noise interval for chromatographic noise calculation be 20x the peak width at half height (rather than the previous 5x).
  2. See Overview of USP Monographs.

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