Chromatography Forum

I am trying to find Ent kaurenoic acid in My cell culture. I am using shimadzu IT-TOF. I have standard. Molecular weight is 302 (C20H30O2) . I am not able to go down detection limit less than 10ug/ml and also I see major peak as 369 instead of 301(M-H)- whichi sodium formate adduct. When I try to break 301 peak it does not show any daughter ions. I do see peak 303 (M+H) in positive with daughter ion of 257. How should i lower down my dection limit and what will be the daughter ions for this molecules..help will be appreciated

I am trying to find Ent kaurenoic acid in My cell culture. I am using shimadzu IT-TOF. I have standard. Molecular weight is 302 (C20H30O2) . I am not able to go down detection limit less than 10ug/ml and also I see major peak as 369 instead of 301(M-H)- whichi sodium formate adduct. When I try to break 301 peak it does not show any daughter ions. I do see peak 303 (M+H) in positive with daughter ion of 257. How should i lower down my dection limit and what will be the daughter ions for this molecules..help will be appreciated

Did you increase Collision energy level in POS mode?

I am not expert but you could try
1) raise pH(where you are?)
2) decrease formate concentration(what you have?)
3) try to see if positive even better?
4) test to see if your analyte was lost in your glass ware.

If possible let us know your progress.

Good luck