Hello,
I try to develop an analytical HPLC method for a glycophospholipid.
The detector is an ELSD. After many tests, the best results were recorded with a gradient going from a H2O/CH3CN 1:1 eluent to a H2O/Isopropanol 1:9 with (for both eluents) X mM of triethylammonium hydrogen carbonate.
I tried with 5, 10 and 15 mM of triethylammonium hydrogen carbonate. The Retention Time for my product were 16, 19 and 14 [mn]. I chose eluent with 10 mM of triethylammonium hydrogen carbonate.
My problem is that with time (~24 [h]), I can have a difference in RT going until 1 mn. And worse when I prepare again my eluents, this difference in RT can grow until 5 [mn].
Do someone has an idea of this sensibility to eluents preparations ?
Thanks

Hi Fab,
which column do You use?
Triethylammonium is an ion pairing reagent and can interact with your stationary phase. Especially on reversed phase columns ion pairing reagents often interact with silanol functions that have not been endcapped and it takes very long till these processes equilibrate or sometimes itīs almost impossible to get real good reproducibility between column batches or even from day to day.So one idea is to use relative retention to a validated internal standard.