How do I calculate Relative Response Factor?

[gonzjr]

All,

I am using a GC method for reaction monitoring with 2 starting reagents(A + B) that will turn into end product (C). The structures are very different so I can't use just Area % analysis because the % content of A would be way off.

Also, the solvent in the reaction evaporates so I can't just use a calibration curve to determine how much of A is being used and how much of C is being formed, since the volume of the reaction is changing.

I would like to know the %amount of A relative to end product C using a relative response factor to correct for underestimation or overestimation.

Can anyone help me?

[AICMM]

gonzjr,


Since no one else has taken a crack at this, I will throw out my two cents worth.

Two things to chew on. 1) Can you follow the total volume of the reaction in some other manner? If so, just track the A and C components with normal calibration curve. mg/ml X total volume (in ml) gives you amount of A and C. Probably not that simple so.....2) Can you add a fourth, non-reactive, non-volatile component (hexadecane for example) at low level at the beginning to track the evaporation effect?

Best regards.

[krickos]

All,

I am using a GC method for reaction monitoring with 2 starting reagents(A + B) that will turn into end product (C). The structures are very different so I can't use just Area % analysis because the % content of A would be way off.

Also, the solvent in the reaction evaporates so I can't just use a calibration curve to determine how much of A is being used and how much of C is being formed, since the volume of the reaction is changing.

I would like to know the %amount of A relative to end product C using a relative response factor to correct for underestimation or overestimation.

Can anyone help me?

Hi

First perhaps have a good discussion with the processchemist on what happens in the reaction and what is needed to monitor. As in most in process controls you get a "momentarily" view of whats going on. Please also eleborate on the evapouration in the process.
ie does the total volume change during the reaction? Not atypical that you use condensors during the reaction and AFTER reaction is complete evapouration is performed.

As you obviously can get hold of A, B and C. You can determine respons factors and as such use correction factors in the evaluation.

As AICMM suggested if solvent in sample evapurates really quick and mess up sample preparing when handling in lab add a suitble solvent that does not interfere with your analysis.

In process controls are fundamentally not always an exact science so to speak, sometimes it is good enough to see the realtive outcome to control the process and thats something to discuss with the processchemists.