By Anonymous on Wednesday, October 15, 2003 - 03:00 pm:
Hi, All,
I have a question on how to set the specification for peak resolution during a method development process. The product peak is well separated to other major impurities. But there is a minor impurity that close to major peak. The peak area percentage of the minor impurity is about 0.5% while the major peak is about 90%. The resolution I calculated is about 1.3. Is this good enough for method validation? Please comments. Thanks.
By Anonymous on Thursday, October 16, 2003 - 05:18 am:
small co-eluting peak can be accepted if it is less than 20% of the response of your analyte at the quantification limit.
However it is not a long way from R=1.3 to R=2 and I would give it a try to especially if you need to work at low concentrations. Co-eluting impurity can cause problems later (e.g. if it get bigger than 20% of LOQ).
By Einar Pontén - SeQuant AB on Thursday, October 16, 2003 - 02:58 pm:
The resolution should be at least 1.5 to be considered sufficient.
For the reasons mentioned by "Anon II" you should strive for a Rs eq or > than 2 during method development.
By A.Mouse on Monday, October 20, 2003 - 05:01 am:
For the quantification of impurity peaks, the resolution needed depends on the ratio of parent peak to impurity peak. If the ratio is 1000 or even 10000, you need a resolution of around 2.
By A.Mouse on Monday, October 20, 2003 - 05:03 am:
I did not see that you give the ratio. In your case, for a ratio of 180, 1.5 is just about good enough.