An Atomic Absorption Spectrometer (AAS) consists of several key components, each serving a specific role in analyzing metal elements. The main components are:
1. Light Source
- Usually a Hollow Cathode Lamp (HCL) or Electrodeless Discharge Lamp (EDL).
- Emits element-specific light that matches the absorption wavelength of the analyte.
- Ensures selectivity, so only the element of interest absorbs the light.
2. Atomizer
- Converts the sample into free atoms in the gaseous state.
- Two common types:
- Flame Atomizer: Uses a flame (acetylene-air or acetylene-nitrous oxide) to atomize the sample.
- Graphite Furnace (Electrothermal) Atomizer: Uses high temperatures in a graphite tube for atomization, allowing detection of very low concentrations.
3. Monochromator
- Isolates the specific wavelength of light absorbed by the element.
- Eliminates interference from other wavelengths.
- Ensures only light absorbed by the element reaches the detector.
4. Detector
- Measures the intensity of transmitted light.
- Common types: photomultiplier tube (PMT) or photodiode.
- Converts light signals into electrical signals proportional to absorption.
5. Signal Processor / Readout System
- Amplifies and processes the detector signal.
- Displays the absorbance, which is then used to calculate the concentration of the element using a calibration curve.
6. Sample Introduction System
- Includes nebulizer (for liquid samples) or other systems to introduce the sample into the atomizer.
- Ensures uniform and reproducible atomization.
Summary:
The workflow in an AAS is:
Light Source → Atomizer → Monochromator → Detector → Signal Processor
This arrangement allows precise and selective measurement of metal concentrations in various samples.