What is the Difference Between Absorbance and Fluorescence?

Absorbance and fluorescence are both analytical techniques used to detect and measure substances in various fields, but they differ in several aspects:

1. Definition: Absorbance is a measure of the capacity of a substance to absorb light of a specific wavelength. Fluorescence, on the other hand, is the emission of light from a substance that has absorbed energy previously.
2. Sensitivity: The most sensitive spectrophotometer can detect as low as 0.75 nanograms per microliter of sample. Fluorescence analysis assays can detect 0.005 nanograms per microliter of sample.
3. Dynamic Range: Absorbance has a higher dynamic range than fluorescence, capable of detecting up to 37,500 nanograms per microliter. Fluorescence has a lower dynamic range, able to detect up to 4,000 nanograms per microliter.
4. Sample Preparation: Absorbance does not require sample preparation, as no dilution or assay preparation is necessary. Fluorescence requires sample preparation, with the sample of interest being bound with fluorescent reagents in an assay kit.
5. Contamination Detection: Many contaminants can be identified using absorbance measurement across an array of wavelengths. Fluorescence is unable to identify contamination within a sample.
6. Effectiveness: Fluorescence is more effective than absorbance due to the highly specific nature of the assay.

In summary, absorbance spectroscopy measures the absorption of light, while fluorescence spectroscopy measures the emission of light after absorption. Both techniques are used in life science laboratories, but they have distinct differences in sensitivity, dynamic range, sample preparation, contamination detection, and effectiveness.

Comparative Table: Absorbance vs Fluorescence

Here is a table comparing the differences between absorbance and fluorescence:

Both absorbance and fluorescence analysis are used to detect and quantify analytes in a sample, but they have distinct differences in terms of sensitivity, sample preparation, and effectiveness.