UV VIS spectra - First derivative spectra

J

jampot

#1
Does anyone know how to obtain the first derivative spectra from a UV/VIS spectra? The software package we use does not allow this calculation.

Any advice would be greatly appreciated.

Jampot
 
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Tim Folkerts

Super Moderator
#2
The derivative of intensity as a function of wavelength is dI/d(lambda). This can be approximated by Delta(I)/Delta(lambda).

If you have the raw data and can import it into a spreadsheet, you can can calculate the difference in intensity between one point and the next, then calculate the difference in wavelength between one point and the next. Divide the first by the second, and you have the derivative.

NOTE: Any noise in the original spectra will tend to get amplified if you take a derivative. You might want to smooth the data at the end of it looks too noisy.


Tim F
 
J

jampot

#3
Tim
Thanks for this. So you plot dI/dlambda (Yaxis) against the original wavelength.

Eg if data is:

Lambda Absorbance
400 0.9
410 1.0
420 1.1
430 1.25

then the first derivative values for 400, 410, and 420nm will be:
0.01, 0.01 and 0.015 respectively

Jampot
 
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