| Author | Message | ||
     Gabi Levin (gabiruth) Member Username: gabiruth Post Number: 14 Registered: 5-2009 |
Lois could also be right in the interpretation of the signal being lost, but without clarification from Fred, we are hust guessing. Gabi | ||
| Lois Weyer (lois_weyer) Senior Member Username: lois_weyer Post Number: 28 Registered: 7-2002 |
If you mean that the signal is lost because the absorption is too high, I would try using a dispersive instrument instead of FTIR if possible. I've found the dynamic range to be better. Another choice would be a variable pathlength flowcell, or just a thinner pathlength? | ||
| Gabi Levin (gabiruth) Member Username: gabiruth Post Number: 13 Registered: 5-2009 |
Hi Fred, first I would like to know the reason why you loose siganl - do you mean the signal specific to one of your reactants? If so, your reaction is probably fast and the reactants disapper fast. If this is the case, it appears that by adding solvent you dilute the reactants, thus reducing reaction rate, giving you more time before the reactants are down to concentration below detetcion. If slowing the reaction is OK - then go ahead and dilute the reactants to begin with by your method. I still think you will probably need same amount of solvent, maybe not. The alternative might be, if the time it takes to circulate the liquid through the side mounted flow cell is too long, is to insert aprobe inside the vessel and follow from there - it might give you some edge. Sticking a probe can be easy, can be difficult, depending on your reactor design. I hope it helps. Gabi Levin Brimrose | ||
| Fred Korpel (fred_korpel) New member Username: fred_korpel Post Number: 2 Registered: 8-2008 |
In our process I have an NIR flow cell that I use to monitor the reaction. The flow cell is installed in a circulation line over the reactor. Because of the changing composition of the reaction mixture I lose the signal halfway the reaction step. Adding solvent to the reactor helps to extend the time before I lose the signal but the amount required is too much. I am intending to mix in the solvent in the circulation line. In this way I need less solvent. The calculated concentrations will be compensated for the measured amount of solvent that is added. Does anybody have experience with this method? |