Download Atomic Absorption Spectrometry

Atomic Absorption
Spectrometry
Dr Zarina Zakaria
University Malaysia Perlis
Instrumentation

An atomic absorption spectrophotometer
consists of a light source, a sample
compartment and a detector.
Applications

Atomic spectroscopy is one of the major
tools for of trace (ppm and ppb) metallic
elements in industrial and environmental
laboratories.
Comparison Between AAS and
UV/Vis Spectroscopy
 Both
methods are used to determine the
concentration of an element in solution.
 Both methods use a standard curve.
 Difference between UV and IR
spectroscopy is that sample must be
atomised where the analyte are converted
into free atom.
 This is called the atomization concept.
Continue…….


In this concept, it is important to convert
an analyte in solid, liquid or solution form
to a free gaseous atom.
Sample may be atomised by:
(1) A flame atomizers
(2) Electrothermal atomizers/graphite furnace
Instrumentation for an Atomic Absorption Spectrometer. The
flowing fuel and air mixture provides the aspiration action drawing
the solution sample into the flame.
Atomic Absorption Spectroscopy


In atomic absorption spectroscopy the
radiation of the lines of the analyte are
produced by the lamp; the presence of the
atomic state of the analyte in the flame
attenuates or reduces the intensity of the
radiation.
The absorbance is proportional to the
concentration of the analyte, similar to
optical spectroscopy.
Upper Diagram is AES and the lower one is AAS.
In FES the flame provides the excitation, but in
AAS it provides only for the atomization .
Hollow Cathode Lamp
The light source in AAS is the hollow cathode lamp (HCL).
The cathode is constructed of the metal or metals of the
analysis. Passage of a dc voltage through the lamp produces
the specific lines of those elements.
Atomic Absorption Spectroscopy

The signal from the detector is transferred to the
computer, and the output registers on the
monitor in a manner specified by the user.
Spectra output of the multi-element steel hollow
cathode lamp. Note the extremely sharp spectral lines.
Atomic Absorption Spectrometry

Most widely used method for determination of
single elements in analytical chemistry

Quantification of energy absorbed from an
incident radiation source from the promotion of
elemental electrons from the ground state

Technique relies on a source of free elemental
atoms electronically excited by monochromatic
light
Sample Introduction in AAS
 Flame
– Method of supplying atom source
– Utilizes a nebulizer in conjunction with
air/acetylene flame
– Solvent evaporates
– Metal salt vaporizes and is reduced to
complete the atomization process
 Radiation
source is a hollow cathode lamp
Pesanan
 Tolong
the 1st
bacakan juga topik separation
topik.
 Lecture notes on Infrared
spectroscopy saya tak upload coz tak
berkaitan.