I am new in the field of GC and I am wondering about the response I am getting from an FID. The area response for a large hydrocarbon (C24) is about 15% the predicted value for direct injection. I am wondering where I could get information about the efficiency of the FID for breaking down this size hydrocarbons.
Thanks.

You can increase split ration

Many things can affect the response of hydrocarbons on an FID, and very few of them have anything to do with efficiency of breaking down the hydrocarbons. C24 is not that large a hydrocarbon, so you should get good response. I have never done quantitation above C44, but if you look at the chromatograms from column companies they all have chromatograms going above C60.

You need to be sure you are using an appropriate column, that the injector is hot enough to vaporize the compounds, and that there is no discrimination in the injector. Be sure that the detector is set hot enough to allow the heavier compounds to pass into the flame, and that the detector is actually heating to the set point. Verify everything, including using a new standard if you are not sure of the quality of the old one. If all of this is ok, you should be getting good response.

It would be helpful to know the conditions you are using for the analysis. There is really not enough information to know where to start to suggest the most likely trouble spot.

I agree with Ron. Knowing the conditions of the system will be an aid. I'm assuming the FID has been checked for correct flows, size of jet, and the detector signal ranges are set correctly. What type of integration and baseline? Are you performing any column compensation? Are you using a programmable temperature Direct injector? What method are you running, D2887 Simulated Distillation?
And lastly, how are you estimating the response for a C24 Peak, I would like to know.

I agree with the previous respondees. Additional info. would help to figure out your problem. One additional suggestion is if you could provide more about your sample (i.e. molecular weight range of your sample) I am leaning toward injector descrimination. Are you using split or splitless mode for your injector?

As you are new to chromatography, I can suggest some good references and they include Grob's fourth edition on GC and Walter Jennings books on capillary chromatography(assumming you are doing CC).

Thank you all for you help and insight. The problem has actually solved itself as it turns out the peak in question is not the one that I was looking for. Some contamination had gotten into the capillary column and caused a large ghost peak. I will post again if any further questions come up. Thanks again.

WHAT IS THAT QUANTITY WHICH DONOT SHOW BY detactor?
in NANOGRAM?