I am conducting a batch adsorption test in other to plot the isotherm
I chose a concentration range from between 3ppm-100ppm of the initial analyte and I had to plot a calibration curve which covers this chosen range.
The absorbance of 50ppm and above is more than (>1). Can I use the values like this?
How do I calculate the concentration from absorbance values(>1) using the calibration curve
UV-Vis reading is usually fine till 3. To calculate the concentration, you simply plot the calibration curve i.e. standard concentration (x-axis) vs absorbance (y-axis) then use the plot equation y = ax+b to calculate x (concentration) which = (y-b)/a
Dear Amen,
I do not recommend that you use absorbance values above 1. At such high values, the effects that are observed are not completely linear and the conclusions can be erroneous.
Best,
Fran
Francisco Manuel Marquez Thank you for your response. Please kindly suggest how I would quantify the 100ppm since its always give an adsorbance of > 1
Dear Amen,
From my point of view, a more appropriate way would be to make a calibration line using solutions that do not exceed an absorbance=1. If the sample to be measured is outside the calibration line, the method would be only indicative, because a calibration requires that the values are within the calibration line.
Best,
Fran
Could you send me the data? If possible the raw, actually really measured data (voltage, pixel value,..?), not the transformed (absorbance).
I would like to try them with my software www.lerenisplezant.be/fitting.htm