Chromatography Forum

hi friends,
We are trying to develope tropine content in a drug product by ELSD as it is UV inactive. We are not getting the response at lower level (10 ppm) which is a requirement as per the specification. Has anyone come across such method.

Since you are defining detectability in concentration terms, what about simply injecting a larger volume (especially if your diluent is weaker than your mobile phase)?

hi friends,
We are trying to develope tropine content in a drug product by ELSD as it is UV inactive. We are not getting the response at lower level (10 ppm) which is a requirement as per the specification. Has anyone come across such method.

Hi
Do you have resolve the problem about tropine ?I also want to develop the mrthod for it with HPLCELSD .for the HPLC method , colum ,mobile phase information !Can you help me ?

Tropine is too volatile to be detected by ELSD under the separation condition. There are some posibilities that you can consider:

1. Select a proper column that can retain and separate tropine in TFA containing mobile phase. The adduct of tropine.TFA should be detected by ELSD or CAD. I need to point out that to obatin low ppm level sensitivity, your better shot is CAD not ELSD; or
2. Use MS or electro-chemical detection; or
3. Use IC and conductivity detection.

Tropine is too volatile to be detected by ELSD under the separation condition. There are some posibilities that you can consider:

1. Select a proper column that can retain and separate tropine in TFA containing mobile phase. The adduct of tropine.TFA should be detected by ELSD or CAD. I need to point out that to obatin low ppm level sensitivity, your better shot is CAD not ELSD; or
2. Use MS or electro-chemical detection; or
3. Use IC and conductivity detection.

Thank you for your advice,it is very helpful for me! But I have no CAD ,only DAD, uv ,and RID! The tropine is inactive to UV , revealed end absorption by UV scan! I also tried testing by UV at 200、205nm……,but on result!
I know ELSD maybe have problem in sensitivity,but now because the instruments I really have no idea except with ELSD .However,UV is a good select if a end wavelength can be used.
Very pleased to know you! Can you give me more advice?

Yes, tropine should have a useful absorption in the UV if you can use a mobile phase with very low absorption. Tom suggested how to get the sensitivity up.