How to Deal with Overlapping Absorbances in Spectrophotometry?

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SUMMARY

The discussion focuses on techniques for addressing overlapping absorbances in spectrophotometry, particularly when multiple species absorb at the same wavelength. It emphasizes the importance of determining the optimal wavelength from the excitation/absorption spectrum and obtaining two emission spectra: one from the sample and another from a blank. Subtracting the blank's emission spectrum from the sample's allows for the isolation of the desired species' emission curve. Proper preparation of the blank is crucial for accurate results.

PREREQUISITES
  • Understanding of spectrophotometry principles
  • Familiarity with excitation and absorption spectra
  • Knowledge of emission spectrum analysis
  • Experience in preparing blank samples for spectroscopic analysis
NEXT STEPS
  • Study the process of preparing blank samples in spectrophotometric analysis
  • Learn about excitation and absorption spectrum interpretation
  • Research techniques for isolating specific absorbance peaks
  • Explore software tools for analyzing emission spectra
USEFUL FOR

This discussion is beneficial for chemists, laboratory technicians, and researchers involved in analytical chemistry, particularly those working with spectrophotometric methods and seeking to improve the accuracy of their measurements in the presence of interfering species.

thenewbosco
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Just a quick question about technique.

The procedure calls for analysis at a wavelength where the absorbance is a (relative) maximum. Suppose there are one or more interfering species in solution, which also absorb more or less strongly at this same wavelength. How could/should one deal with such a situation of overlapping absorbances?

Thanks for your help.
 
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I think it depends on what you are measuring. If you are sceptical of contaminants then you should make other tests of that sample to be sure of it. :rolleyes:
 
thenewbosco said:
Just a quick question about technique.

The procedure calls for analysis at a wavelength where the absorbance is a (relative) maximum. Suppose there are one or more interfering species in solution, which also absorb more or less strongly at this same wavelength. How could/should one deal with such a situation of overlapping absorbances?

Thanks for your help.
Typically, you determine the optimal wavelength from the excitation/absorption spectrum and obtain two emission spectra - one on the system under study and the second on a blank. The preparation of the blank is highly non-trivial, but the idea is that by subtracting the emission spectrum of the blank from that of the given system, you obtain the emission curve for the required species.

The blank may also be used in the selection of a suitable absorbance maximum.
 

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