Chromatography Forum

Dear all

I am wondering if there is any guideline or criteria to follow to:
Once the HPLC sequence (blanks, SST, samples and Std) is started but the order to the equipment is to run till last SST injection and then wait till we confirm the SST is valid to continue with the sample injections, is there any limit of time between the las SST injection and the samples injection that we should meet?
thanks in advance for your insights and comments
KR
Georgina

There is not much guidance on this from any compendial source I can think of.

There *should* be some guidance available in your lab's SOPs, but I've seldom seen anything beyond some statements about deal breakers which generally indicate that so long as you leave the system running and change little to nothing (except maybe to reduce the flow rate to conserve mobile phase), you can leave a system for as long as it takes to confirm your SST results. Overnight is even fair game but I strongly suspect that over a weekend is asking for trouble.

Better: most data systems have a means of automating at least one aspect of SST evaluation and can be setup to stop a run when things are not going well. Use that capability on your analysis' most prone to failure SST result and get your runs done faster.

If the [bracketing] SST and Std injected after the samples are OK, the waiting time is OK as well.

Thank you for your question. The scenario you’ve described—where you run an HPLC sequence up to the last SST (System Suitability Test) injection and then pause before proceeding with the sample injections—is common in laboratories to ensure the system is functioning correctly before analyzing samples. However, there are typically no strict universal guidelines regarding the allowable time between the last SST injection and the start of the sample injections. Geometry Dash

The scenario you’ve described—where you run an HPLC sequence up to the last SST (System Suitability Test) injection and then pause before proceeding with the sample injections—is common in laboratories to ensure the system is functioning correctly before analyzing samples.

When I was working, the company had about 15 cGMP assays for consumer products, developed and validated as per cGMP in house (mostly by me). We had Agilent HPLC and GC units, primarily with "A.06 through A.10" versions of Chemstations, and I'd set up those sequences with Sequence Summary Reports/SST Reports to be automatically calculated at the end of the sequence. It would be quite rare for us to check/confirm initial SST offline while a sequence was running, and I cannot remember waiting until after initial SST had been confirmed before starting sample injections.

My current employer expects samples to not get injected until SST has been confirmed.
Personally, I find it a lot easier to have it written into SOPs that any injections made after a failure to establish positive SST results must be disregarded, thus allowing people to start their runs and move on in cases where establishing SST takes a while.