GCECD response

[seet]

Hi all,

I would like to ask is it possible the internal std of a method i get back the similar response area from last month and this month In gcecd, however d std compound will get lower? Because i do suspect is the standard issue, however after try out the new std, the signal response also bias low same as before encounter problem. May i know why?
note: when i unplug d ecd column nut, i notice that the output is grew up slowly, however i notice last time when i unplug the nut, the output will grew up quite fast till 8k to 10k figure. may i know what is the root cause?
Thanks

[rb6banjo]

Do you expect the analyte to be stable in your standard solution? Sometimes, the behavior you are describing can occur when you have active sites in the sample-flow path of your system. If you could reveal the identity of your analytes (the internal standard and the the material of interest), we could get a better idea of the likelihood of adsorption in your system.