Derivative Spectroscopy
First introduced in the 1950s, derivative spectroscopy is an analytical technique that applies derivative calculations to absorbance spectra. This approach mathematically reduces the interference caused by scattering from undissolved particles.
Concept
When the 1st and 2nd derivatives are applied to a sinusoidal single-peak signal, the resulting output becomes a three-peak signal, with each new peak having a narrower base than the original as shown here:
Application
This technique can be applied to any spectral shape. In the upper section of the following illustration, the pink line represents the absorbance spectrum of a caffeine sample, which shows undissolved material (*note the signal at 300 nm is neither flat nor zero*). The blue line represents the spectrum of a completely dissolved pure standard. When the 2nd derivative is applied to both spectra, as shown in the lower section, both exhibit the same spectral shape.
Rainbow R6 and 2nd Derivative Spectroscopy: Advantages Over Traditional UV-Vis Methods
The Rainbow R6 utilizes 2nd Derivative Spectroscopy, offering several advantages compared to traditional UV-Vis methodologies:
- Up to 8 experiments can be conducted simultaneously.
- No need for sample filtration.
- Sample readings can be taken as frequently as every 3 seconds.
- Real-time measurement of Absorbance, Concentration, and %Dissolved during the experiment.
- Capabilities for dual-component analysis.
- Potential for separating components using spectroscopy.
Pion’s user base consistently experiences how 2nd Derivative Spectroscopy excels in conditions where traditional methods may struggle.
Dual-Component Analysis
As mentioned earlier, applying the 2nd derivative converts a single-peak spectrum into a three-peak spectrum. This feature is employed by *AuPro*, Pion’s proprietary software, to analyze two-component mixtures. When one component shows a spectral signal in regions where the other component has zero contribution, and vice versa, the Zero Intercept Method can be applied.
