Chromatography Forum

Hello Everybody.

We are running EP rel substances and something strange happened.

The peak areas is almost half the size than normally. I asked another analyst to prepare a new standard , but the peak size is still half of the normal size. There is no shift in the retention times, could not see any leaks either. The injection volume was set up to correct one.
All other peak , the solution peak on the start of the chromatogram is also half of the size...
any ideas ? I don't think that this is due incorrectly prepared mobile phase either..

Hello

Put some information about instrument (brand, model etc)
It could be "injection system" depends what you have. I'd check:

-injection valve (rotor seal)
-syringe (if you have one)
-sample loop
-metering device

Regards

Tomasz Kubowicz

Before checking ^ - have a look at the instrument method - any recent changes to sampling rate?