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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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Presentation Transcript
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

Fig 3-3Grotrian diagrams for Na

2. Theoretical Concepts⑴Integral Formula of AASFig 3-4 Typical Shape of A Atomic Absorption line

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)

(3.7)

va>> ve,

and

v0a= v0e,

then kv≈k0,

(3.10)

(3.10)

4. Characteristic Concentration

(3.11)

(3.12)

3.2. Atomic Absorption Instrumentation

2. line source (Hollow Cathode Lamp )

Fig 3-13

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

4. Control of Analytical Interferences

Ionization interference

Matrix interference

Chemical interference

Background interference

Ba → Ba+ + e-

K → K+ + e-

AHCL= Aa+ Ab

(4.14)

(4.15)

• Graphite furnace atomizer components

• The Graphite Furnace Power Supply and Programmer

• Quantitative analysis GFAAS

• Effect of Matrix on Height and Area

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