Excitation
E
Relaxation
Excited State
Ground State
+ hv
Excited State
Ground State
Photon
Spectral Region
Vacuum UV
160
Ultra-Violet
190
Visible
360
Wavelength = nm
Near IR
760
900
Effect of Temperature on Emission
Wavelength increasing ->
200
300
400
600
800
5000 k
As Pb
Mn Mg
Cu
Ca
Ba
Na
Li
K
Mg
Cu
Ca
Ba
Na
Li
K
Na
Li
K
3000 k
2000 k
Ca
FOTOMETRIA A FIAMMA
1: bruciatore
2: monocromatore
3: rivelatore
4: elaborazione del segnale
ICP is shorthand for ICP-AES or ICP-OES.
What is ICP-AES? It is:
Inductively Coupled Plasma Atomic Emission Spectrometer.
What is ICP-OES? It is:
Inductively Coupled Plasma Optical Emission Spectrometer.
• Typical analysis time for ICP is ~2-3 minutes. This includes flush
time, multiple repeats, printing, etc. (Analysis time is independent
of the number of elements being determined)
• Typical precision, amongst repeats within an analysis, is ~0.5%
• Typical drift is ≤ 2% per hour
• Typical detection limits are ~ 1-10 parts per billion
A - Argon gas is swirled through the torch. B - RF power is applied to
the load coil. C - A spark produces some free electrons in the argon. D - The free electrons
are accelerated by the RF fields causing further ionization and
forming a plasma. E - The sample aerosol-carrying nebulizer flow punches a hole in the
plasma
Instrument Components
1.
Sample
Introduction
2.
Energy
Source
3.
6.
Computer and
Software
5.
Spectrometer
Electronics
4.
Detector
Instrument Components
1. Sample
Introduction
i.
the Peristaltic
pump
ii.
the Nebulizer
iii.
the Spray
chamber
Instrument Components
2. Energy
Source
There are three basic parts to the
energy source.
i. the Radio frequency generator
which generates an oscillating electomagnetic field at a frequency of 27.12 million
cycles per second. This radiation is directed
to
ii.the Load coil
which delivers the radiation to
iii. the Torch
which has argon flowing through it which will
form a plasma in the RF field.
Il campione viene introdotto nel plasma tramite una pompa peristalstica che eroga un
flusso costante compreso tra 0.1 ml/min (ICP-MS) e 1 ml/min (ICP-AES)
Nel nebulizzatore pneumatico, il campione viene
trascinato attraverso un tubo capillare per mezzo
di un flusso di gas nebulizzante (il cosiddetto
effetto Bernoulli). L’aerosol generato nella
camera di nebulizzazione subisce una selezione
sulla base delle dimensioni: le gocce più piccole
(~ 1-2 %) sono trasportate al plasma, mentre
quelle più grosse sono scartate