Hello, I need a help from those of you who work on Kinetex EVO C18 with water + 0.2% TFA mobile phase (isocratic).
The conditions are constant (temperatures, flow, column, conditioning time). The peaks from the glutathione standard are at different retention times - the difference is more than 1 minute and it varies, depending on the day). The column has been used for 2 months, only for this analyses. Do any of you have experience with such a column ? Can it be something wrong with the stationary phase?