System suitability requirement

[surinzp]

Hi all,

Can anyone please tell me,what is the system suitability criteria as per the USP and EP when you are running a HPLC related substances method.How frequently i need to inject the system suitability solution(is it ok if i inject my SS solution after every 6 sample injections?).

Thanks

[krickos]

Hi

Sadly there is not an answer that fits all.

In general there are 3-4 sources for your SST.

1. The monograph may contain specific ones like resolution, efficency
2. General chapters like <621> and 2.2.48 sets general requirements (typically RSD, tailing factor and signal to noise requirements)
3. Analytical technical chapters may set other requirements usually not for HPLC but for CE or residual solvents testing for example.
4. Scientific judgement/soundness. Like bracketing it is usually up to the individual company to set the bracketing interval based on internal SOPs and/or based on data when testing/validating the method.

Injecting a SST solution every 6-8 sample for long assay runs is a good call in my experiance. For related substances you have to decide whats most important to recheck as in some cases resulution may be more critical but in others signal to noise can be more or equally important to recheck now and then or in end of sequence.

When it comes to EP and assys it is also worth to note that the specification and number of injected standards sets the requirement for RSD. USP seems to or already have implemented the same things (not in office currently so can not check).

[surinzp]

Hi Krikos,

Thanks for the information.Its really helpful.

Please tell me if anyone have different views on SST bracketings.

Thanks

[Rob Burgess]

I would only use bracketing standards throughout the run if I was running content assay methods.

For related substances (impurity) methods I would only run a suitable standard (to measure things like resolution, tailing or sensitivity) at the start and end of the chromatographic run.