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# C hapter 3 Atomic Absorption Spectroscopy - PowerPoint PPT Presentation

C hapter 3 Atomic Absorption Spectroscopy. 3.1. Theoretical Concepts 3.2. Atomic Absorption Instrumentation 3.3. Graphite Furnace Atomic Absorption 3.4. Control of Analytical Interferences. 3.1. Theoretical Concepts. The Atomic Absorption Process Theoretical Concepts

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C hapter 3 Atomic Absorption Spectroscopy

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### Chapter 3 Atomic Absorption Spectroscopy

3.1. Theoretical Concepts

3.2. Atomic Absorption Instrumentation

3.3. Graphite Furnace Atomic Absorption

3.4. Control of Analytical Interferences

### 3.1. Theoretical Concepts

• The Atomic Absorption Process

• Theoretical Concepts

• Quantitative Analysis

• Characteristic Concentration

• Detection Limits

### The Atomic Absorption Process

Fig3-2 Grotrian diagrams for K

Fig 3-3Grotrian diagrams for Na

### Integral Absorption FormulaBy atomic theory

(3.1)

By Line Shape Function

( the Nature distribute )

(3.2)

The Peak Absorption Coefficient k0 is:

(3.3)

### ⑵ Peak Absorption Theoryby Lambert-Beer’s Law:

(3.4)

(3.5)

(3.6)

The Absorbance is:

(3.7)

When:

va>> ve,

and

v0a= v0e,

then kv≈k0,

(3.8)

(3.9)

(3.10)

(3.10)

(3.11)

(3.12)

Fig 3-13

Fig 3-14

### 3. Atomizer for AAS (Pre-Mix Burner System)

Fig 4-19 Tree Type Burner Head for different Type Flame

### 4. Control of Analytical Interferences

Ionization interference

Matrix interference

Chemical interference

Background interference

Ba → Ba+ + e-

K → K+ + e-

(4.13)

AHCL= Aa+ Ab

(4.14)

(4.15)

### 3.3. Graphite Furnace Atomic Absorption

• Graphite furnace atomizer components

• The Graphite Furnace Power Supply and Programmer

• Quantitative analysis GFAAS

• Effect of Matrix on Height and Area

### 1. Graphite furnace atomizer components

The Graphite Furnace Atomizer

A basic graphite furnace atomizer is comprised of the following components:

· graphite tube

· electrical contacts

· enclosed water cooled housing

· inert purge gas controls

THGA graphite tube

Fig 4-27

• The Graphite Furnace Power Supply and Programmer

• A Graphite Furnace Temperature Program

• Drying

• Pyrolysis

• Cool Down(optional)

• Atomization

• Clean Out

• Cool Down