what is the requirement of retention time in usp?

[weeker2001]

if i inject 4 times in two vials .what is the reqirement of RT ?
rsd? or other requirements ? in my empower2 software ,the default setting is ±5%,sometimes i integrate the peak with the reference standard's RT ,but i cannot got infomation from the sample because of the drift of sample .should i set the RT ±10% or other options ?

[Mattias]

A well functioning LC system should have no problem to keep the RT of the peaks within 1% - so it sounds as you have some problem with the check valves or fluctuating column temp.

Regarding the accepted RT window - it is up to you to set the requirements.

[weeker2001]

thank you for your reply, my hplc is 2695-2996,certainly with the column oven,the drift of rt is not the reason of temperature. i do analysis the roxithromycin ,with the +-10%setting ,i can integrate ,and with the +-5%setting ,i cannot get the response from the data method.now what i am concerning is what is the rule of the rt requirements .which kinds of points i must consider .such as the RSDof RT .or what is the requirement beween reference standards RT and sample RT?
are there any requirements of such item ?
if there be , what i can get ?
USP ,ICH ,EP ,JP or others ?
i am in a government lab under SFDA(china)

[Mattias]

How much difference in RT you can tolerate is very different between different methods. If you only have one peak in the chromatogram you hardly need any requirements, if you have lots you will need to be more careful.

That is why there are no general rules to this. You will have to make a scientific judgement of what is acceptable in each method

[DR]

If there is one from which you gleaned your method, consult the USP monograph for any suitability requirements.

[Consumer Products Guy]

We typically use %RSD less than 2%, with 5 injections. For both retention times and peak areas.

[shahis77]

I agree we also use %RSD of 2% for 5 injections.