Inductively coupled plasma atomic emission spectroscopy (ICP-AES) uses a plasma to produce excited atoms and ions that emit electromagnetic radiation at wavelengths specific to elements. The document discusses how ICP-AES works, including that a sample is nebulized and transported to the plasma where it is atomized and excited, emitting radiation measured by a spectrometer. Common applications are clinical, environmental, pharmaceutical and industrial analysis to determine trace metal concentrations.
2. Introduction:
Atomic emission spectroscopy (AES or OES) uses quantitative measurement
of the optical emission from excited atoms to determine analyte concentration.
EMISSION SOURCES:
Flames
Arcs / Sparks
Direct Current Plasmas (DCP)
Plasma sources
Inductively Coupled Plasmas (ICP)
Microwave induced Plasmas(MIP)
3. Inductively coupled plasma atomic emission spectroscopy (ICP-AES), also referred to as
inductively coupled plasma optical emission spectrometry (ICP-OES) - is a type of
emission spectroscopy that uses the inductively coupled plasma to produce excited atoms
and ions that emit electromagnetic radiation at wavelengths characteristic of a particular
element.
Sample solution
containing elements
Formation of
liquid droplets
atomization
excitation
Emission of
Radiation at a
Specific Wave
Length
Measure the
intensity of
emitted
radiation
5. ICP-AES utilizes a plasma as the atomization & excitation source.
A plasma is an electrically neutral , highly ionized gas that consists of ions
electrons&atoms.
The energy that maintains an analytical plasma is derived from an electric or
magnetic field.
NEBULIZERS:
Nebulizers are devices that convert a liquid into an aerosol that can be
transported to the plasma.
TYPES OF NEBULIZERS
Concentric nebulizer
Micro concentric nebulizer
Cross flow nebulizer
Babington nebulizer
7. PUMPS:
Peristaltic pumps are almost exclusively
the pumps of choice for ICP-AES.
The pumps utilize a series of rollers that
push the sample solution through the tubing
using a process known as peristalsis.
With a pumped solution, the flow rate of
the solution into the nebulizer is fixed and is
not as dependent on solution parameters such
as viscosity and surface tension.
8. SPRAY CHAMBER:
A spray chamber is placed between the
nebulizer & the torch.
The primary function of the spray chamber
is to remove large droplets from the aerosol.
The secondary purpose is to smooth out pulses
that occur during nebulization due to pumping of the solution.
It is designed to allow droplets with diameters
of about 10 micrometre or smaller to pass to the plasma.
10. DETECTION:
2 types of detection-Viewing Positions
SOP: Side-on-Plasma EOP: End-on-Plasma
more suitable for hard matrices (concentrated samples);
alkali metals (Na, K, Li) calibration is more linear;
less spectral interferences;
lower sensitivity (Limit-of-Detection is higher);
more suitable for light matrices;
alkali metals (Na, K, Li) calibration is less linear;
more spectral interferences;
higher sensitivity (Limit-of-Detection is lower);
11. HOW TO PERFORM SIMULTANEOUS ANALYSIS
Spectrometers:
Function-To isolate specific spectral lines emitted from the analyte from all of the
other emissions produced by the other atoms,ions&molecules within plasma.
There are several devices available
Monochromators
Simultaneous analysis was carried out by using:
Polychromators , which are Paschen-Runge optics coupled to highly sensitivity
detectors known as Photomultiplers(PMT).
Echelle grating optics, coupled to solid state detectors(CCD,CID) also known as
Charge transfer devices.
12. a. light passes through the entrance slit.
b. It is reflected off a collimating mirror on to a diffracting grating.
c. As the grating rotates the light separates into its different spectral components,and
passes the desired wavelength to the second collimating mirror.
d. The monochromatic light focuses on to exit slit positioned in front of the detector.
14. PMT is to convert optical rotation(photons) into an electrical signal(electrons).The
vaccum tube devices are very sensitive&cover a large wavelength range.
It consists of a vaccum photocell with an anode, photocathode and a number
of dynodes which have an increasingly positive potential with respect to the photocathode.
15. Clinical Analysis: metals in biological fluids (blood, urine).
Environmental Analysis: trace metals and other elements in waters, soils,
plants, composts and sludges.
Pharmaceuticals: traces of catalysts used; traces of poison metals (Cd, Pb
etc).
Industry: trace metal analysis in raw materials; noble metals determination.
Forensic science: gunshot powder residue analysis, toxicological examination
( e.g., thallium (Tl) determination.
16. Boss, C.B. and Freden, K.J. Concepts, Instrumentation and Techniques in
Inductively Coupled Plasma Optical Emission Spectrometry. 1997
Skoog, D. Fundamentals of Analytical Chemistry, 2004
Inductively Coupled Plasmas in Analytical Atomic Spectrometry; Montaser, A.;
Golightly, D. W., Eds.; VCH Publishers: New York, 1988
Fredeen, C. B. (n.d.). http://www.atoomspectrometrie.nl/Icpconceptsbook.pdf.