Peak in void volume

[sharma]

Dear All,

I am in QC. I would like to know whether peaks appearing in void volume around 1-2 minutes in the impurities test should be reported in toal or can we ignore them (no peak coming in blank at this RT)?

Regards

[HPLCaddict]

*cynical*What does your SOP say about this?

Honestly, I'd say there are two sides about this topic. From an analytical point of view, peaks in the void volume are highly imprecise and inaccurate, so it's usually considered analytical nonsense to try to quantify them. Remember that HPLC is all about equillibria, and at t0 your systems' equillibrium is highly distorted.
Unfortunately, there's auditors, inspectors and bosses that might have a look at your data, and these guys are not always prone to analytical common sense. So, if you want to be on the safe side, integrate those peaks and treat them as unknowns - and cross your fingers that you don't create an OOS!
Did you try a placebo injection (with the exact same solvent composition as your sample)? You might see those peaks there, and then it would be justified to completely neglect them.

[Gerhard Kratz]

If you get those Peaks on a RP column I highly recommend to check with a HILIC column if there are relevant compounds. You never know if there are some byproducts not retarded on a RP-column.