I have taken 1000 PPM of nanoparticles in 1 ml of RO water and pursuing its UV visible spectro absorbance scan. They are showing respective peaks on the baseis of energy transition of electrons present in the chemical moities attached on the NP surface. Next, i want to analyze the concentration of these NPs. I applied Beer Lambert law A= ECL but not getting back the answer to be 1000ppm or 1 mg/ml or 1 microgram/L. How is that possible? please explain.
Drishti Garg You have assigned UV adsorption to nanoparticles of a certain concentration. Immediately say yourself that the spectrum appears not from nanoparticles, but from the molecules of the substance adsorbed on the nanoparticles. You need to determine what is the concentration of molecules adsorbed on nanoparticles. You need to determine the concentration of adsorbed substances from the adsorption curve. To do this, plot the calibration forward intensity of the maximum absorption of the UV band of aqueous solutions of different concentrations of your substance. Knowing the intensity, you can determine the amount of adsorbed substance on your nanoparticles.
Depending on the size of the nanoparticles, the Beer-Lambert law may not be suitable because of light scattering (turbidity) from the particles. This issue becomes more important as the particle size increases and as the wavelength decreases.
For particles of a given size, the amount of scattered light (measured at right angles to the incident light) is proportional to the particle concentration, as long as the particles are dilute, so as to avoid multiple scattering.
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