Chromatography Forum

Hi there,

It would be a great help if you can assist me with this.

Simply put is the TCD Detector Response always linear, is this a myth?

What are some variables that could affect the detector response.

As an example, would one be able to assume that the response is linear for CO2, with sample size ranging from 0-150ul.

Is non-linearity in detector response likely to arise from very small volumes or very large volumes.

Is non-linearity due to column specifications or detector quality?

I am just trying to find out what specs/events/gases will cause the response of a TCD detector to be non-linear.

Just to clarify, the response is linear to CO2, but I want to find out if it could be non-linear to other gases and what would cause it?
Thank you.

a TCD will have limits and the first limit of which I am certain is size of the sample. Both low and high, I am sure linearity is lost. Now to specify the actual limits is most likely determined by the analyte itself.

Other factors are the design of the detector, the temperature at which it is operated, and the flow rate through the detector.

It is best that you determine the linearity of your research analytes yourself on your hardware if this information is critical to your work. But these are the factors you should vary in your research.

Good luck,

Rod

Thanks Rod,

I will begin testing the high and low limits to linearity right away.

One more question on the upper limit to the linear response of the TCD detector. Does it depend on the component?

If a component has a high detector response, I am guessing that the TCD response could possibly
become non-linear sooner than a component with a lower response? Is this possible?

Because then my upper and lower linear tests would have to be repeated per component.

Thanks again.

I suspect different analytes might have different maximum limits. I also suspect the difference between them might be very very small.

All the published reports I have seen on detector research only used one analyte for TCD theoretical limits.

So we are dealing with speculation here. FYI

best wishes,

ROd