I have done UV spectrometer to calculate the unknown concentration of 2 mixture compound. As through lambert equation first I have to know the absorbance coefficient of individual compound . I had done that but I got 2 different plot and different wavelength because once I had done with sonicating the nanoparticles and another without sonication. How will I know which slope I should take to calculate unknown concentration of mixture sample. like for TiO2 ( 320-330)nm I got k=0.0077 and (420-430)nm I got k=0.0063.
Hi,
The sonicated and non-sonicated samples are not really comparable due to aggregation. I recommend you to always sonicate your nanoparticle suspensions before analyzing with a spectrometer.
David
David is absolutely right - but anyway, in a plot of Absorbance versus concentration, (for fixed pathlength), the slope is related to the extinction co-efficient, which will be different for different wavelengths, according to the absorption spectrum.
So how will I know which coefficient I should take to put in Beer Lambert Law to check the unknown concentration. @ Hugh J Byrne
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