Frequently Asked Question

The instrumentation process in spectrophotometry is different from Atomic Absorption Spectroscopy (AAS) in several ways:

1. Light Source
- Spectrophotometry: Uses a continuous light source, typically a tungsten or deuterium lamp, which emits light across a wide range of wavelengths.
- AAS: Uses a hollow cathode lamp (HCL) or an electrodeless discharge lamp (EDL) that emits light at a specific wavelength characteristic of the element being analyzed.

2. Sample Introduction
- Spectrophotometry: The sample is typically placed in a cuvette or test tube and inserted into the light path.
- AAS: The sample is often introduced into a flame or furnace, where it is atomized and excited.

3. Wavelength Selection
- Spectrophotometry: Uses a monochromator or a filter to select a specific wavelength of light.
- AAS: Uses a monochromator to isolate the characteristic wavelength of the element being analyzed.

4. Detector
- Spectrophotometry: Uses a photodetector, such as a photomultiplier tube or a photodiode, to measure the intensity of the transmitted or absorbed light.
- AAS: Uses a photomultiplier tube or a charge-coupled device (CCD) detector to measure the intensity of the light emitted by the excited atoms.

5. Data Analysis
- Spectrophotometry: The absorbance or transmittance of the sample is measured and used to determine the concentration of the analyte.
- AAS: The absorbance of the sample is measured at the characteristic wavelength of the element being analyzed, and the concentration is determined using a calibration curve.

These differences in instrumentation lead to different applications for spectrophotometry and AAS. Spectrophotometry is generally used for qualitative and quantitative analysis of a wide variety of compounds, while AAS is specifically used for the quantitative analysis of metals and other elements.