I have a assay where absorbance has to be measured and in which the A% value is given and I want to find out the % of the material present.
The method is according to the pharmacopeia .
please guide.
Little konwledge of analytical chemistry and pharma QC are also needed in order to avoid arriving to the wrong conclusión!
Sir please tell me what is thr meaning of this factor A(1%, 1cm)? Do we have to consider the dilution also ( if there is any) along with this calculation? And what is 'b' and 'c' in your abhove equation.? After measuring the absorbace how to use this factor along with the absorbance and dilutions to arrive at the result??
It is a value of typical sensitivity of a given analyte determined by a specific method. It does not mean that you don't need to calibrate your instrument, but often one needs to have some rough idea on sensitivity to check the method or to optimize sample preparation. In QC, high deviations from typical values may indicate some matrix or contamination problem, or some problem with the instrument. So I would recommend to calibrate your instrument according to your assay and to calculate the concentration needed for 1% absorption from your calibration curve. This should not differ too much from the typical value.
Mr fischer my instrument is perfect and working .
i have taken the absorption also with the necessary dilutions.
but i have some issue in the calculations part.
do we have to divide the "A" factor given with the absorbance ?
Dear Ashray, thank you for telling by e-mail that you have no standards for calibration, but that you need to rely in the extinction coeffcient. If you use 1 cm cuvettes c% is calculated as measured absorbance, divided by A(1%, 1 cm).
Mr Fischer, might I ask you something? what is the disadvantage using A1% 1 cm for the calculation? thank you before
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