ICP-MS (inductively coupled plasma mass spectrometry) is an analytical technique used to detect and measure elements in chemical samples. It works by ionizing atoms from a sample using an inductively coupled plasma and then detecting the mass-to-charge ratios of the resulting ions using a mass spectrometer. ICP-MS can detect elements at concentrations as low as parts per trillion and has a wide working range of nine orders of magnitude. It is capable of isotopic analysis and multi-element detection across most of the periodic table. ICP-MS has various applications in fields like medicine, materials science, and environmental analysis.

1. ICP-MS (Inductively coupled plasma
mass spectrometry)
MRIDU KULWANT
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3. INTRODUCTION
 ICP (Inductively Coupled Plasma) Spectroscopy is an analytical method used to
detect and measure elements to analyze chemical samples. The process is based on
the ionization of a sample by an extremely hot plasma, usually made from argon
gas. The instrumentation itself consists of optics, mechanics, electronics, and signal
processing.
 four main methods of optical spectroscopy are absorption, emission, luminescence,
and scattering.
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 There also are several other spectrometric methods for observing optical quantities,
including reflection, refraction, diffraction, polarization, refractive index change,
and acoustic waves.

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ICP
TYPES
 unique to other forms of inorganic mass spectrometry is its
ability to sample the analyte continuously, without
interruption.
 Instrument detection limits are at or below the single part
per trillion (ppt) level for much of the periodic table
 Analytical working range is nine orders of magnitude
 Productivity is unsurpassed by any other technique
 Isotopic analysis can be achieved readily
ICP-MS

5. Source: https://resources.perkinelmer.com/corporate/cmsresources/images/44-74849tch_icpmsthirtyminuteguide.pdf
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The elements shown in color in Figure can be analyzed by ICP-MS with detection
limits at or below the ppb range. Elements that are in white are either not measurable
by ICP-MS (the upper right-hand side) or do not have naturally occurring isotopes.

6. PRINCIPLE
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 The ICP-MS instrument measures most of the elements in the periodic table.
 An inductively coupled plasma is a plasma that is energized (ionized)
by inductively heating the gas with an electromagnetic coil, and contains a
sufficient concentration of ions and electrons to make the gas electrically
conductive.
 In its simplest form, ICP-MS takes a pre-prepared liquid containing the analyte,
pumps it through a nebulizer to create an aerosol which is introduced into an argon
gas plasma. The high temperature of the plasma (~5500-6500 K) is sufficient to
atomize and ionize almost all elements, including those with the highest ionization
potentials.
 ICP-MS can be used to measure the
individual isotopes of each element;
this capability brings value to
laboratory studies.
 interested in one specific isotope of
an element or in the ratio between
two isotopes of an element.
 By using a semi-quantitative software package, an unknown sample can be
analyzed for 80 elements in three minutes, providing semi-quantitative data
that is typically within ±30% of the quantitative values.

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ICP-MS ICP-AES
Plasma Horizontal: generates cations
Vertical: excites atoms, which
emit photons
Ion detection Mass-to-charge ratio Wavelength of emitted light
Detection limit 1-10 ppt 1-10 ppb
Working range 8 orders of magnitude 6 orders of magnitude
Throughput 20-30 elements per minute 10-40 elements per minute
Isotope detection Yes No
Cost ~$150,000 ~$50,000
Multi-element detection Yes Yes
Spectral interferences Predictable, less than 300
Much greater in number and
more complicated to correct
Routine accessories
Electro thermal vaporization, laser
ablation, high-performance liquid
chromatography, etc.
Rare
In ICP-AES, the ions are excited by vertical plasma, emitting photons that are separated on
the basis of their emission wavelengths. As implied by the name, ICP-MS separates the
ions, generated by horizontal plasma, on the basis of their mass-to-charge ratios (m/z).
COMPARISON of ICP-MS and ICP-AES

8.  light source
 sampling interface,
 peristaltic pump leading to a nebulizer,
 spray chamber,
 plasma torch,
 detector,
 ion-focusing system,
 mass-separation device,
 vacuum chamber, maintained by turbo molecular
pumps
INSTRUMENTATION
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9. LIGHT SOURCE
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ICP
torch
 An inductively coupled plasma (ICP) or transformer coupled
plasma (TCP) is a type of plasma source in which the energy is
supplied by electric currents which are produced by electromagnetic
induction, that is, by time-varying magnetic fields.
 Plasma electron temperatures can range between ~6,000 K and
~10,000 K (~6 eV – ~100 eV)
 The plasma used in an ICP-MS is made by
partially ionizing argon gas (Ar → Ar+ +
e−). The energy required for this reaction is
obtained by pulsing an alternating electric
current in load coil that surrounds the
plasma torch with a flow of argon gas.
 The plasmas used in spectro-chemical analysis are essentially
electrically neutral, with each positive charge on an ion balanced by a
free electron.
 In these plasmas the positive ions are almost all singly charged and
there are few negative ions, so there are nearly equal numbers of ions
and electrons in each unit volume of plasma.

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NEBULIZER
 The basic operation works as follows: a liquid sample is pumped into the nebulizer
to convert the sample into a spray.
 An internal standard, such as germanium, is pumped into a mixer along with the
sample prior to nebulization to compensate for matrix effects.
 ICP-MS system operates with an
Nebulizer, in which a high
velocity Argon gas stream meets a
liquid stream causing film wise
breakup of the solution into a fine
aerosol. The aerosol particle size
should ideally be sub-10µm with a
narrow particle size distribution to
achieve efficient atomization and
ionization.
 For coupling to mass spectrometry, the ions from the plasma are extracted through a
series of cones into a mass spectrometer, usually a quadrupole. The ions are
separated on the basis of their mass-to-charge ratio and a detector receives an ion
signal proportional to the concentration.

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 The plasma dries the aerosol, dissociates the molecules, and then removes an
electron from the components, thereby forming singly-charged ions, which are
directed into a mass filtering device known as the mass spectrometer.
 The carrier gas is sent through the central channel and into the very hot plasma.
 The sample is then exposed to radio frequency which converts the gas into a plasma.
The high temperature of the plasma is sufficient to cause a very large portion of the
sample to form ions. This fraction of ionization can approach 100% for some
elements (e.g. sodium), but this is dependent on the ionization potential.
 Mass Spectrometer– acts as a mass filter to sort ions by their mass-to-charge ratio
(m/z).
MASS SPECTROMETER
GASES used
 ICP-MS uses an argon (Ar) plasma – the ICP – to convert the sample into ions that
are then measured using a mass spectrometer – the MS. ICP-MS.
 Helium (He) is often used as an aerosol carrier gas in 193 nm ArF excimer laser
ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis
because it increases the signal intensity compared with that obtained using argon
(Ar).

12. DETECTOR
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 Detector – counts individual ions exiting the quadrupole.
 The mass separation device separates these ions based on their mass-to-charge
ratio.
 An ion detector then converts these ions into an electrical signal, which is
multiplied and read by computer software.
 Photons that reach the detector can be erroneously counted as ions, which increases
background and degrades detection limits.
VACUUM CHAMBER
 vacuum chamber, maintained by turbo molecular pumps.
 An ICP torch operates at room pressure and at an elevated temperature, and a mass
spectrometer, operates under a vacuum and at room temperature.

13. APPLICATIONS
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Qualitative and Semi quantitative Applications: One of the strengths of ICP-MS is
its ability to provide a survey scan, that allows for the identification of the elements
present in a sample. Analysis of a single sample that contains known concentrations of
these elements is suitable for providing a rough estimate of their concentration in the
sample.
Quantitative Analysis: For a more accurate and precise quantitative analysis, one can
prepare multiple external standards and prepare a calibration curve. Linearly across
approximately six orders of magnitude with detection limits of less than 1 ppb.
Including an internal standard in the external standards can help reduce matrix effects.
The ideal internal standard will not produce isobaric ions and its primary ionization
potential should be similar to that for the analyte; when working with several analyte, it
may be necessary to choose a different internal standard for each analyte.
 Medical
 Pharmaceutical
 Materials and metallurgy
 Nuclear
 Nanotechnology
 Food and beverage (including wine and drinking
water analysis and pesticide screening)
 Natural resource
exploration
 Petrochemicals
 Environmental
(including soil
analysis)
 Regulatory

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REFERENCES
ICP-MS
 https://pt.slideshare.net/moshfekus/icp-ms
 https://www.intertek.com/chemicals/icp-analysis/
 https://www.hitachihightech.com/global/products/science/tech/ana/icp/description
s/icp-oes.html
 https://www.xrfscientific.com/what-is-icp-spectroscopy/
 https://en.wikipedia.org/wiki/Inductively_coupled_plasma
 https://www.thermofisher.com
 https://chem.libretexts.org/Bookshelves/Analytical_Chemistry/Physical_Methods
_in_Chemistry_and_Nano_Science_(Barron)/01%3A_Elemental_Analysis/1.06%
3A_ICP-MS_for_Trace_Metal_Analysis