Dear all I am doing some organic transformation reaction and i want to know that how we can calculate by % conversion or yield of our product with reference to starting material, either by using internal standard (IS) method or without IS method?
reaction is like A-------B
or A-------B + C + A (where B is my desired product)?
Dear Rajeev,
The fastest way is to make relative quantification (without IS). You just have to integrate the peaks in your chromatogram and do a relation with the initial concentration of your reactant. Analyze your mixture @ t=0 (only A), integrate the peak (you should have only one peak) : the area is proportional to the initial concentration. Then analyze your mixture @ the end of reaction, integrate all the peaks obtained, and calculate the concentration by comparison with the analysis @ t=0. Do the same at least 3 times, to get an error bar. This method is fast, works well, is not very accurate, but should be enough to calculate a conversion % of an organic reaction.
With IS, you'll get the real concentration of your reactants/products, the method is accurate, but longer to implement. Do a calibration curve with A, B, C,... by adding in your standard solutions an internal standard at a fixed concentration (1 for each target analyte, the best is a deuterated equivalent of your analyte). Add the same concentration of IS in your sample solutions. Analyze all, integrate all the peaks. Draw the calibration curve as A(analyte)/A(is) = f (Qanalyte/Q(is) (area ratio = f(quantity ratio). You will access the concentration of all you target analyte (via the area ratio), and thus be able to calculate the conversion %.
In case of comparison of relative abundance for zero time and other points you can think about headspace analysis - if compound B is volatile.
In case of internal standard method (also in connection with headspace) you need to perform a calibration.
Regards
G
As per the previous answers you need a calibration (linearity curve of response versus mass or concentration) in order to be accurate, since the detector response varies with each molecule.
I want to know one thing in this regard, that do we need to have product already to calculate the response factor? As in the formula, we need to have response of analyte in standard sample.
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