Posted by Chemist as Yahoo Answers on Jun 21, 2007
“What is the response factor in chromatography?” is a question on Yahoo Answers.
So far there has been two answers:
1) A wordy and a bit confusing text book reply tailored more towards Gas Chromatography.
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.
2) This cute answer is from “Alright22″ who obviously had “hands-on” experience with chromatography - thin-layer chromatography of M&M candies.
It depends on the experiment. If you rub a green m & m into a solvent and place the filter into the solvent, the dye used to make the green will soak into the filter into bars of yellow and blue, and thus you will prove they are using yellow and blue dye to make green tints on m & ms. The response factor may be how quickly the result appears, or how much evidence is revealed, or how long the experiment will take.
So far these are all the answers received. Let’s see if anybody else would shine more light on the response factor in chromatography.
Tags: chromatography Gas Chromatography
24 Responses
josh
April 21st, 2008 at 4:25 pm
1The response factor is simply the ratio of concentration of analyte to the area (of the peak in a chromatogram) produced by that concentration, that is to say F=C/A. Response factors can be used in conjunction with an internal standard whose response factor has already been quantified previously in a dedicated chromatographic run.
AVN PRASAD
April 28th, 2008 at 2:36 am
2response factor in HPLC & GC
Ashok
May 14th, 2008 at 5:51 am
3Suppose you give one rupee alms to five beggars,the response of these beggeres will be different for this same action,at a given time depending on the need .Now if we need to quantify this reaction, into a measurable quantity and then compare we use what is called as response as factor
Matt
October 14th, 2008 at 4:24 am
4response factor (RF) = concentration/response.
(In GC the response is usually the area below a peak)
rearranging the equation gives you the concentration:
Conc = RF x Response
BUT: The RF may change for different concentrations. That is why you need to make a calibration curve. If the curve is linear then you can use the average of the response factors to calculate the conc. If the curve is non-linear (e.g. quadratic) You will need to use a quadratic equation that describes the line of best fit through your data to calculate the conc.
If you are using internal standard, the relative response factor (RRF) is the ratio of the response factors of the internal standard (RFis) and the analyte (RFa)
RRF = RFa/Ris
To determine analyte concentration for linear data:
analyte response x IS conc.
analyte conc. = _______________________
IS response x average relative RF
(where the average RRF is found from your calibration curve)
if the response of your analyte increases relative to your IS the concentration increases, BUT if the response of your IS and analyte decrease or increase EQUALLY (e.g. due to changed instrument conditions) then the concentration stays the same. In this way IS compensates for method variability
Matt
October 14th, 2008 at 4:26 am
5The equation above should read:
analyte conc = (analyte response x IS conc)/(IS response x avg RRF)
Bethany
November 6th, 2008 at 4:38 pm
6Matt is on the correct path but has the equation set up incorrectly.
Response Factor (RF)= (Response(area) of Standard)/(Concentration of Standard)
Therefore,
Analyte(sample) Concentration = (Response of Analyte)/RF
These equations can be used to determine analyte concentration over a linear concentration range using chromatographic methods (e.g. HPLC, GC, etc). A calibration curve must be created to determine linearity over the desired concentration for each analyte being quantified.
Chaz
November 18th, 2008 at 4:19 am
7What if you have areas of everything but no concentrations. I have volumes but usually in our lab if req’d to use density they provide it. That’s the path I’ve taken so far but it seems a little, to quote one of my fav cartoons, janeky.
tiptoisolournese
December 29th, 2008 at 11:41 am
8okndtaqutdutyigvwell, hi admin adn people nice forum indeed. how’s life? hope it’s introduce branch
umesh
April 20th, 2009 at 9:52 am
9dear sir, i have querry of rf i n pcb analysis. my boss has given data and he told me find conc. and responce factor.
data is—
rt–3.296
responce—-7409031
shift—–0.002
conc——
answer me about this resonce factor. injected amount 0.2 micro-litre.
second
aiman
April 22nd, 2009 at 6:25 pm
10hello everybody, just want to ask how to determine final concentration using gc:
given data
initial concentration 0.8mg/L
R time= 2.141
Area= 2413613
ABC
May 6th, 2009 at 2:50 am
11Umesh,your information is insufficient.
Khan
June 24th, 2009 at 1:44 pm
12Hi every body,
I need help in HPLC, actually I am trying to find retinol in serum on HPLC.
I am using Retinyl acetate as my internal Standard. Can anyone tell me the stepwise procedure to find the concentration of retinol after I get the responce by Height and Area.
Thanks.
asif Khan
June 28th, 2009 at 4:39 am
13if g.c gives H2S results in say 15 ppmv how can we convert it into ppmw please help me
N.SIVA JYOTHI
August 11th, 2009 at 4:44 am
14what is the difference between response factor and correction factor?
mystmonkey
January 13th, 2010 at 4:59 am
15Internal standard how much do i put and why , how do i choose the internal standard . I am working on identifying the volatile constituents of some fruits and their quantities using GC and HPLC . how do i kno which internal standard and what quantities of it should i use .
amol
January 30th, 2010 at 6:30 am
16how i calculate response factor in HPLC
amol
January 30th, 2010 at 6:30 am
17how i calculate response factor in hplc ?
mojtab
February 4th, 2010 at 10:50 am
18please help me.
i want calculation of response factor in gc .
thanks
kishore
February 14th, 2010 at 11:44 am
19Respcted sir
I want to know about response factor and validation of analytical methods calculations.
rohini.k
February 18th, 2010 at 4:54 am
20We calculate RF in calculation sheet as multify the given RF Value.
GOPI
March 7th, 2010 at 4:11 pm
21why use caffiene for hplc calibration
elle
March 27th, 2010 at 8:48 am
22Dear sir,
I’ve been doing a research about caffeine in certain brands of coffee using GC/MSD. The problem is that i don’t know how to calculate the amount of caffeine using the area that obtained from GC/MSD. How am i going to calculate the amount of caffeine?? What information should i have? And what formula should i use? Please help me. Please3…
m.r
April 21st, 2010 at 11:55 pm
23Dear sir,
please help me.
I want quntitive of response factor 1,3 butadiene relative of vinyl actylene in gc .
for example if RF 1,3 BD 4.2
Vinyl actylene (1-butene-3-yne)= ???
thanks
surya 4m hyd
June 3rd, 2010 at 12:12 am
24dear sir, I want to know actual response of a known impurity in my sample. is there any relation between RRF & area percent of that impurity obtained in the sample?
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