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Peaks slightly shift by 0.1 min in standard vs sample, Why?
Posted: Thu Sep 24, 2020 2:24 pm
by chemist23
Hello,
I am injecting sugar standards and tobacco samples on HPLC-RID. The standard is prepared in pure water and the sample is extract in pure water. When I compare the peaks found in the standard vs sample, there is a slight shift of about 0.1 min in the sample. Why is this even though diluent is the same?
Re: Peaks slightly shift by 0.1 min in standard vs sample, Why?
Posted: Thu Sep 24, 2020 3:44 pm
by James_Ball
One thing I can think of is tobacco has a lot of salts in it, so maybe that is creating a slight buffer solution with a different pH than the standards and causing the retention time shift.
Have you tried using a buffer solution for both extracts and standards? It might be what is needed to stabilize the retention times.
Re: Peaks slightly shift by 0.1 min in standard vs sample, Why?
Posted: Fri Oct 16, 2020 8:48 pm
by pwm
Are the peaks youre comparing the same area?
Re: Peaks slightly shift by 0.1 min in standard vs sample, Why?
Posted: Wed Oct 21, 2020 1:32 pm
by lmh
… and if you need to demonstrate that the shift is caused by the chemistry of the sample, and isn't merely that you're looking at the wrong peak, you can run a mixed vial containing a mix of standard and sample. If the sample is causing the standard to elute at a slightly different retention time, you will get one peak. If the peak in the sample isn't the same as the standard, you will get two peaks.