How much Retention time shift (HPLC)in Quality Control methods is permitted in the same run. When I say the same run, what I mean is that you are running standard and sample injections one after the other, on the same day and on the same instrument. Is there a guidance or rule on this. How much variation is permitted from day to day or instrument to instrument or column to column.

I will appreciate any comments or suggestions or references in this matter.

A separate question:

Is having a method validation protocol a GMP requirement. What if you perform method validation without a protocol?

Thanks in advance for your help.

Sean

Hi:

As to your second question. This happened at our company. If you validate without a protocol, you get to revalidate after the protocol is written and approved. You'll double your work.

depends on the method. is your column thermostated? you might want to evaluate your data from the method validation and set limit for RT in the method system suitability test. At least you should do this if the retention time looks to be a critical parameter. Most softwares notifies you if you fall outside the window. I believe default value is usually 2%? RSD < 1% is peace of cake with modern systems.

keep in mind that RT is usually the only factor you use to identify compunds.

few websites:

http://www.waters.com/watersdivision/waters_website/Applications/validate/sys_sut.asp

http://pubs.acs.org/subscribe/journals/tcaw/10/i09/html/09dong.html