[sony]

 

[sjb]

What do your abbreviations mean? http://en.wikipedia.org/w/index.php?title=RRT&oldid=300555625 and http://en.wikipedia.org/w/index.php?title=RRF&oldid=290848807 don't seem to have much in common...

[malditogrillo]

im pretty sure RRF means relative response factor.  not sure what RRT is. 

but 

http://www.justchromatography.com/yahoo-answers/response-factor

    Response Factor

    The size of a spectral peak is proportional to the amount of the substance that reaches the detector in the GC instrument. No detector responds equally to different compounds. Results using one detector will probably differ from results obtained using another detector. Therefore, comparing analytical results to tabulated experimental data using a different detector does not provide a reliable identification of the specimen.

    A “response factor” must be calculated for each substance with a particular detector. A response factor is obtained experimentally by analyzing a known quantity of the substance into the GC instrument and measuring the area of the relevant peak. The experimental conditions (temperature, pressure, carrier gas flow rate) must be identical to those used to analyze the specimen. The response factor equals the area of the spectral peak divided by the weight or volume of the substance injected. If the technician applies the proper technique, of running a standard sample before and after running the specimen, determining a response factor is not necessary.




I know that you can calculate RRF by taking the area of target peak divided by concentration of analyte injected. 


is RRT relative retention time?

[marquis]

The idea with the response factor is to generate an amount of unknown, based on the area of an unknown peak of the same retention time.

You generate a response factor by taking a standard of known weight, injecting it, and seeing what area the standard generates.  You then calculate (or have the instrument calculate) the response factor.  It takes the standard weight and divides by the standard area.

When you set up the calculation, you take your unknown area and multiply it by the response factor to get an amount of sample.  The amount of sample is usually in grams or milligrams.  So for the units to work out right, your response factor has to be in grams/area. This seems to be the inverse of how you are listing the response factor.

amount of unknown (g)= rf (g/area) x peak area

As for the relative portion, no two columns or gcs are exactly alike.  Even with the same flow, temp,etc. The retention times will never exactly match.  So often an internal standard is included and retention times are calculated relative to the internal standard.

I've done those tests, but we never used the labels of relative retention time or relative response factor.

Good luck and hope this helps.

[Train]

I think that RRF is a correction factor that accounts for the different molar absorptivities of other peaks vs your main analyte.  In other words, "relative" means the response factor of the sample component relative to the response factor of your main analyte or standard (I guess it could be on a per weight concentration or a molar concentration basis). 

For example, if you want to determine chromatographic purity by area % and the components in your sample have significantly different molar absorptivities then if you use the uncorrected area your results will be skewed toward the components with the highest molar absorptivities.  A good example is benzaldehyde vs benzyl alcohol.  You can get the same peak area with a much more dilute solution of benzaldehyde as opposed to benzyl alcohol.

[JGK]

For RRT

http://wiki.answers.com/Q/How_to_calculate_Relative_retention_time

for resolution and improving it see

http://www.phenomenex.com/resources/default.aspx?id=8565

Ideally you should be looking for a resolution value of 2.0 or greater