Related Experiment Video
Updated: Jul 18, 2026
10:40
High Resolution Phonon-assisted Quasi-resonance Fluorescence Spectroscopy
Published on: June 28, 2016
Hidden isosbestic point(s) in ultraviolet spectra
M-F Pouët1, E Baures, S Vaillant
1Laboratoire Génie de l'Environnement Industriel, Ecole des Mines d'Alès, 6, avenue de Clavières, 30 319 Alès Cédex, France.
Applied Spectroscopy
|December 5, 2006
Summary
Normalization reveals hidden isosbestic points (IP*) in UV-visible spectra, offering new quantitative and qualitative insights. This technique enhances understanding of sample composition changes, with environmental applications.
Area of Science:
- Analytical Chemistry
- Spectroscopy
- Physical Chemistry
Background:
- Isosbestic points in UV-visible spectra indicate conserved sample composition but are often overlooked.
- Their absence, such as during dilution, limits quantitative and qualitative analysis.
- Existing methods rarely exploit isosbestic points for detailed information.
Purpose of the Study:
- To demonstrate that normalization can reveal hidden isosbestic points (IP*) in spectral data.
- To highlight the significance of these normalized hidden isosbestic points for chemical analysis.
- To showcase practical applications of direct and hidden isosbestic points in environmental science.
Main Methods:
- Spectral data analysis using UV-visible spectroscopy.
- Application of a normalization procedure to reveal hidden spectral features.
- Evaluation of conditions required for isosbestic point formation.
Main Results:
- Normalization successfully uncovers previously undetected isosbestic points (IP*).
- The presence of IP* confirms conserved quality and quantity in sample compositions.
- Demonstrated utility of direct and hidden isosbestic points in environmental analysis.
Conclusions:
- Normalization is a valuable tool for revealing hidden isosbestic points in spectral data.
- Isosbestic points, direct or hidden, provide significant quantitative and qualitative information.
- The technique has broad applicability, particularly in environmental monitoring and analysis.
Related Concept Videos
01:16UV–Vis Spectroscopy: Molecular Electronic Transitions
In Ultraviolet–Visible (UV–Vis) spectroscopy, the absorption of electromagnetic radiation is used to probe the electronic structure of molecules. This technique provides insights into molecular electronic transitions, particularly the movement of electrons between different molecular orbitals. Radiation is absorbed if the energy of the electromagnetic radiation passing through the molecule is precisely equal to the energy difference between the excited and ground states. During this process,...
01:32UV–Vis Spectroscopy of Conjugated Systems
Organic compounds with conjugated double bonds show strong absorption features in the UV–visible region of the electromagnetic spectrum attributed to π → π* electronic excitations. Generally, a UV–vis absorption spectrum is recorded as a plot of absorbance vs wavelength. The wavelength of maximum absorbance, which manifests as a peak in the absorption spectrum, is denoted as λmax.
One of the factors influencing λmax is the extent of conjugation in the...
One of the factors influencing λmax is the extent of conjugation in the...
01:23IR Spectrum Peak Broadening: Hydrogen Bonding
The vibrational frequency of a bond is directly proportional to its bond strength. As a result, stronger bonds vibrate at higher frequencies, while weaker bonds vibrate at lower frequencies. The stretching vibration of the strong O–H bond in alcohols and phenols (very dilute solution or gas phase) appears as a sharp peak at 3600–3650 cm−1.
However, the extent of hydrogen bonding influences the observed stretching frequency and band broadening. Intermolecular or intramolecular hydrogen bonding...
However, the extent of hydrogen bonding influences the observed stretching frequency and band broadening. Intermolecular or intramolecular hydrogen bonding...
01:02Ultraviolet and Visible (UV–Vis) Spectroscopy: Overview
Ultraviolet–visible (UV–visible or UV–Vis) spectroscopy is an analytical technique that investigates the interaction between matter and UV–Vis light within the electromagnetic spectrum. This method is widely used for its versatility, simplicity, and relatively quick data acquisition, making it valuable for both qualitative and quantitative analysis. When UV–Vis radiation passes through a material, molecules absorb light depending on the energy required for electronic transitions. As a result...
01:20IR Spectrum Peak Intensity: Dipole Moment
The dipole moment of a bond is the product of the partial charge on either atom and the distance between them. Dipole moments influence the efficiency of IR absorption and the peak intensity. When a bond with a dipole moment is placed in an electric field, the direction of the field determines if the bond is compressed or stretched. Electromagnetic radiation consists of an electric field component that rapidly reverses direction. It follows that polar bonds are alternately stretched and...
01:29UV–Vis Spectroscopy: Woodward–Fieser Rules
UV–Visible absorption spectra of conjugated dienes arise from the lowest energy π → π* transitions. The light-absorbing part of the molecule is called the chromophore, and the substituents directly attached to the chromophore are called auxochromes. A strong correlation exists between the absorption maxima, λmax, and the structure of a conjugated π system. The Woodward–Fieser rules predict the value of λmax for a given structure by adding the contributions...