Here are the lecture notes from the presentation titled 'ICP-OES/MS Analysis: Advancements, Limitations, and Future Applications in Soil and Water Research,' delivered to a group of researchers affiliated with the Soil & Water Department, Faculty of Agriculture, Hebrew University of Jerusalem (Seagram Center) in 2023. The aim was to explore advanced technologies in elemental analysis and their application to soil and water research. The Lecture Notes Brochure (22 pages) can serve as a concise guide to ICP-OES/MS for researchers and students, assisting them in selecting the appropriate technique for their projects

1. 1
“ICP-OES/MS Analysis: Advancements, Limitations, and Future Applications in Soil
and Water Research”, Lecture Notes
‫בירושלים‬ ‫העברית‬ ‫האוניברסיטה‬
THE HEBREW UNIVERSITY OF JERUSALEM
‫וסביבה‬ ‫מזון‬ ,‫לחקלאות‬ ‫הפקולטה‬
Faculty of Agriculture, Food and Environment
Vasiliy V. Rosen, Ph.D. ‫ד"ר‬
‫רוזן‬ ‫וסילי‬
P.O. Box 12, Rehovot 76100, Israel.Tel +972-8-9489975,
Cellular: +972-548820558, Fax +972-8-9489243. Email: icpaes@gmail.com vasiliyr@savion.huji.ac.il

2. 2
Atomic
spectrometry methods are
powerful analytical
techniques used for the
determination of the
concentration of elements
in a sample. In all these
methods the sample is first
introduced into a flame or
plasma, where the
elements of interest are
excited to emit or absorb light at specific wavelengths. Here we will discuss the various
processes that occur in the flame or plasma of an atomic spectrometer.
The first step in the analysis is the aspiration of the liquid sample into the instrument.
Flame photometer uses a flame of propane/butane gas mixture. In the case of atomic absorption
spectrometry (AAS), the sample is introduced into a flame, which is typically an air/acetylene
flame. The sample solution is drawn into a nebulizer, where it is converted into a fine mist or

3. 3
aerosol. The aerosol is then transported into the flame, where it is desolvated, and the atoms of
the elements of interest are vaporized.
In the case of optical emission spectrometry (OES), the sample is introduced into a
plasma, which is typically generated by an argon gas discharge. The sample solution is
aspirated into a nebulizer and converted into a fine aerosol, which is then transported into the
plasma. In the plasma, the atoms of the elements of interest are excited to emit light at specific
wavelengths.
The next step after the aspiration in in all spectrometers is desolvation, which is the
process of removing the solvent from the sample. In AAS, the sample is introduced into a
flame, which is typically around 2,500 to 3,000 degrees Celsius. At this temperature, the
solvent is rapidly evaporated, leaving behind the analyte atoms. In OES, the plasma is at an
even higher temperature, typically around 6,000 to 10,000 degrees Celsius. At this temperature,
the solvent is rapidly vaporized, leaving behind the analyte atoms in the plasma.
The next step is excitation, which is the process of exciting the valent electrons of atoms
to higher energy levels.
In AAS, the energy
of the specific wavelength
produced by the hollow
cathode lamp,
corresponding to the
analyte of interest, is
absorbed by the analyte
atoms and is measured.
The concentration of the
analyte atoms is then
calculated.
In OES, the analyte atoms are excited by collisions with free electrons and other atoms
in the argon plasma. The atoms then return to the ground state and emit light. The ICP-OES
spectrometer optics analyze this light. Based on the emitted wavelength and intensity of light,
the analyte atoms can be identified and their concentrations measured.

4. 4
Some of the analyte atoms are converted to ions with a single charge. ICP-MS identifies
the elements according to their mass-to-charge ratio.
Different stages of the same process (light absorption, light emission, and ion
formation) are utilized by different instrument types.
The temperature of the flame or plasma is an important factor that affects the
performance of different types of atomic spectrometers, including flame photometers, atomic
absorption spectrometers (AA), and optical emission spectrometers (OES). This temperature
can influence the sensitivity, limit of quantitation, and spectral interferences of these
instruments in different ways.

5. 5
The inductively
coupled plasma optical
emission spectrometry (ICP-
OES) is a widely used
analytical technique that
utilizes an ICP torch to
produce a plasma that can
excite the atoms of the analyte
and emit characteristic light
for quantitative analysis. The
ICP torch is an essential
component of the ICP-OES
instrument, and its design plays a crucial role in the performance of the technique.
The ICP torch typically consists of three concentric quartz tubes, which are cooled by
a flow of argon gas to maintain a stable temperature and prevent the torch from melting. The
innermost tube (injection tube) carries the sample droplets to plasma with a flow of argon, and
is surrounded by a second quartz tube that carries the plasma gas flow. The outermost tube
provides an insulating layer of the same argon gas that keeps the heat of the plasma inside the
torch.
The ICP torch generates a plasma by applying a radiofrequency (RF) electric field to
the plasma gas, which ionizes the gas atoms and generates a highly energetic plasma. The
plasma is sustained by the energy from the RF field, and the temperature of the plasma can
reach up to 10,000 Kelvin. The plasma is also highly reactive, making it an efficient source of
excitation for atomic emission spectroscopy.
The ICP torch has several distinct regions with different temperatures and properties.
The Normal Analytical Zone (NAZ) is the region of the plasma where the majority of the
excitation and emission processes occur. The NAZ typically has a temperature of around 6,000
Kelvin and is characterized by a high concentration of excited atoms and ions.

6. 6
In an Inductively
Coupled Plasma (ICP)
spectrometer, the orientation
of the torch can have a
significant impact on the
analysis of samples.
Axial orientation
refers to the direction in
which the plasma torch and
sample aerosol are aligned
with the optical path of the
spectrometer. An axial-view
system “looks” from end to end of the plasma’s entire axis. It basically observes all phenomena
in the excitation channel. This axial-view design allows a large amount of light into the optical
system, and thus makes a relatively large volume of information available to process. For many
analyses, this is a crucial benefit, leading to maximum sensitivity in detecting trace-element
emissions.
However, all that light can contain more than emissions from elements of interest. It
may also include background emissions. The light may be influenced by matrix interferences
such as the easily ionized element (EIE) effect. These can degrade analytical accuracy.
Example: in environmental samples, they can influence the measurement of alkali elements
such as lithium, sodium, and potassium, as well as earth alkali elements such as magnesium or
calcium.
A radial-view system looks across the plasma. It sees only a relatively narrow cross
section of light, rather than light from the whole length of the excitation channel. With less
light to process, a radial system can’t match the sensitivity of an axial system in detecting trace
elements.
However, by observing less light in total, a radial view also reduces or eliminates
certain background emissions and matrix interferences. (Its higher tolerance for challenging
matrices is also due to the use of a vertical plasma torch.) So it suffers less from noise than
axial systems, and usually offers higher analytical precision.

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Offering both radial and axial plasma observations, a dual-view system is designed to
achieve the benefits of both. However, almost all current models must compromise this goal,
favoring one view or the other.
The appropriate orientation for each element and concentration depends on the specific
analytical needs of the samples being analyzed. However, as a general guideline, axial
orientation is recommended for trace elements at low concentrations while radial orientation is
suitable for high concentration elements.
The formal name of
the ICP-OES operated at The
Scientific Service Core
Facility of the Faculty of
Agriculture is the following:
HR (high-resolution) Dual-
View ICP-OES
PlasmaQuant 9000 Elite by
Analytik Jena, Germany. If
your samples were analyzed in
our lab, you may refer to this
name in your report or
scientific manuscript.
The main features of this instrument are:
• V-Shuttle torch, which offers a long lifetime of torch components, minimizes
maintenance and reduces wash-out and sample deposition related issues.
• High frequency generator, which provides a plasma of extraordinary robustness
to run any sample type with minimum efforts and maximum emission yields.
• Dual View Plus plasma observation modes to increase the instruments working
range to a maximum, minimize sample preparation efforts and allow for
efficient measurements.

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• High-resolution optical system to provide interference-free analysis in any kind
of sample matrix with highly reliable data quality.
The formal name of
the ICP-MS operated at
The Scientific Service
Core Facility of the
Faculty of Agriculture is
the following:
PlasmaQuant Elite MS
by Analytik Jena,
Germany. If your samples
were analyzed in our lab,
you may refer to this name
in your report or
manuscript.
The ICP-MS method is a mass spectrometry-based analytic method in the field of
inorganic elemental analysis. In simple terms, it is based on a spectrum analysis of an ionized
sample. The sample being tested is aspirated into a plasma stream, which breaks chemical
bonds and ionizes free atoms. The ion beam is then centered and sent into the mass
spectrometer. Here, the detection system's instrumentation detects single ions as pulses based
on the ratio of their mass to charge (m/z), then matches their signatures to those of trace
elements.

9. 9
The principle
of operation of the
ICP-MS method is
based on mass
spectrometry analysis
of samples ionized in
plasma. Achieving
the desired detection
limits while
maintaining high
long-term stability
and sufficient
robustness against
interference requires a very specific equipment layout. The following components are essential
in an ICP-MS analytic device:
• High-frequency generator: The task of the generator is to (inductively) create
an alternating magnetic field within the plasma coil in order to couple with the
energy in a flow of gas. This process supplies the necessary plasma. The
resonant circuit of the generator is matched to the induction coil and typically
operated with a frequency of 27.12 or 40.68 MHz.
• Plasma torch: The torch is a multi-walled quartz tube whose outer channel
contains the noble gas argon. The open end of the plasma torch is surrounded
by the plasma coil or induction coil, which is responsible for transferring the
energy to the argon stream.
• Plasma coil: The plasma coil is part of the high-frequency generator. It conducts
an oscillating current that generates an electromagnetic field. This field
accelerates charged particles, thereby transmitting energy to the argon plasma.
The noble gas argon is ionized in the process and heated to a temperature
between roughly 6,800 and 10,000 K.
• Sample insertion: A thin injector tube made of quartz, corundum or sapphire is
used to insert the sample. It injects the sample into the plasma with the help of
additional argon, destroying chemical bonds in the sample and ionizing free

10. 10
atoms. The practical implementation of sample injection differs depending on
the state of matter of the sample. With liquid samples, the fluid is atomized
along with argon into a fine aerosol, then fed into the injector tube. Gaseous
samples can generally be connected directly to the injection tube, while solids
are first turned into gas and inserted with a stream of carrier gas.
• Interface: The interface must transport the ionized sample from the plasma and
into the high-vacuum region of the mass spectrometer. At the same time, the
interface is responsible for directing the ion beam to the ion optics, where
extraction lenses collimate the beam. Two conical pinhole apertures, called
"cones", are used to separate the vacuum areas.
• Interference management: In ICP-MS, interference is handled through the use
of collision gases and/or reaction gases. In collision mode, polyatomic
interferences are removed through reduction of kinetic energy or by
dissociation. In reaction mode, interfering ions and polyatomic ions are
converted into new, non-interfering products.
• Ion optics: The ion optics are a lens system that serves to focus the ion beam
and direct it into the mass spectrometer.
• Mass filter: The mass filter usually takes a quadrupole form consisting of four
rods arranged in parallel. These generate an alternating magnetic field that
guides the ions along spiral trajectories. A major performance parameter of ICP-
MS devices is the quadrupole scan rate. It expresses the speed of the
measurement process. High-performance devices achieve scan speeds of over
5,000 amu/s.
• Detection system: At the outlet of the mass filter there is a detection system that
generates a measurement signal proportional to the frequency of the detected
ions. In practice it is typical to use secondary electron multipliers and Faraday
detectors.

11. 11
The history of
the Plasma
Spectrochemistry
Laboratory (ICP Lab) at
the Faculty of
Agriculture started in
1989 when the first ICP-
OES spectrometer by
Spectro (Kleve city,
Germany) was
purchased. Over the
years, several other
models have replaced it. In 2018, the first ICP-MS by Analytik Jena (Jena city, Germany) was
purchased, marking the beginning of a new era in elemental analysis in our lab.
Sample
preparation is a crucial
step in the analysis of
environmental samples for
total elemental content
using Inductively Coupled
Plasma Optical Emission
Spectroscopy (ICP-OES).
While the digestion
process is the most critical
step, the pre-treatment
procedures such as
sampling, washing, drying, grinding, and storage can also have a significant impact on the
accuracy and precision of the final results.
Sampling is the first step in the pre-treatment process and is critical to ensuring that the
sample is representative of the area being tested. The sample should be collected from multiple

12. 12
locations to ensure that it is representative of the entire area being tested. If the sample is not
collected correctly, the results may be biased, leading to inaccurate conclusions.
Washing the sample (usually plant material) is the next step in the pre-treatment
process. Washing the sample is important to remove any surface contaminants that may affect
the accuracy of the final results. However, the type of washing solution used and the washing
procedure may also affect the final results. For example, if the washing solution is not of the
correct pH, it may affect the solubility of certain elements, leading to inaccurate results. Non-
cationic detergent solution, diluted nitric acid (1%), and deionized water are used for successive
washing of the samples before elemental analysis.
Drying the sample is an important step to ensure that the sample is dry before further
processing. However, the drying temperature and time should be controlled to avoid any
changes in the elemental composition of the sample due to thermal reactions. In most cases,
60-70 °C is an appropriate temperature for plant material, sludges and compost, whereas 105
°C is the drying standard for soil samples. Lyophilizing is also the widely used drying method,
especially for biological tissues.
Grinding is the next step in the pre-treatment process and is used to reduce the particle
size of the sample to improve the digestion efficiency. The grinding method used can affect the
homogeneity of the sample, which can have a significant impact on the precision of the final
results. The possible problem of grinding is the pollution of the sample by the material the mill
blades made of: Fe, Cr, Ni, Mo and other metals came from the stainless-steel blades. The
blades (or balls in case of ball-type mill) made of wolfram, zirconia, or ceramic, may be a
solution depending on the research needs.
Storage of the sample is the final pre-treatment step, and it is important to store the
sample correctly to avoid any changes in the elemental composition due to contamination or
chemical reactions. The sample should be stored in a clean, dry container, and the container
should be properly labeled to avoid any mix-ups. Plastic materials are preferred, metal
containers must be avoided. If the sample is not stored correctly, it may also affect the accuracy
of the final results.
In conclusion, the pre-treatment procedures such as sampling, washing, drying,
grinding, and storage are critical to ensure accurate and precise results in ICP-OES analysis of
environmental samples for total elemental content. Each step should be carefully controlled,
and any changes in the procedure should be properly documented to ensure the reproducibility

13. 13
of the results. The accuracy of the final results depends on the quality of the pre-treatment
procedures, and any errors in these procedures may lead to inaccurate conclusions. Therefore,
it is important to pay attention to each step of the pre-treatment process to ensure the accuracy
of the final results.
Sample digestion
is a critical step in ICP-
OES (Inductively
Coupled Plasma-Optical
Emission Spectrometry)
and ICP-MS (Inductively
Coupled Plasma-Mass
Spectrometry) analysis.
It involves the process of
breaking down the
sample matrix to extract
the analyte of interest, which can be analyzed by ICP-OES or ICP-MS. The importance of
sample acid digestion/dissolution for ICP-OES/MS analysis lies in the fact that it helps to
reduce interferences and improve the accuracy of the results. In this response, we will describe
the three most common methods of sample digestion, namely dry ashing, wet digestion using
a hot-block (or hot-plate), and microwave-assisted acid digestion. We will also discuss the
advantage of microwave closed digestion.
Dry Ashing: Dry ashing is a sample digestion technique used primarily for the analysis
of inorganic samples, such as soils and sediments. In this method, the sample is heated in a
furnace at high temperatures (typically between 400-800 °C) until it is completely ashed. The
ash is then dissolved in an acid solution and analyzed by ICP-OES/MS. The dry ashing method
is simple and inexpensive, but it has several limitations. The high temperature required for
ashing can lead to the loss of volatile elements, such as mercury and arsenic. Also, at too high
temperatures the hardly soluble oxides may be formed. Cross-contamination of the samples
during dry ashing procedure is highly likely.

14. 14
Wet Digestion
using Hot-Block
(or Hot-Plate):
Wet digestion
using a hot-block
or hot-plate is a
widely used
method for the
digestion of a
variety of sample
types, including
food, water, and
biological
tissues. In this
method, the sample is first homogenized, and then it is mixed with a strong acid, such as nitric
acid or aqua regia. The mixture is then heated on a hot-block or hot-plate for several hours until
the sample is completely digested (dissolved). The resulting solution is then diluted with
deionized water and analyzed by ICP-OES/MS. This method is simple, effective, and relatively
inexpensive, but it has several limitations. The open conditions of the digestion process can
cause the loss of volatile elements. Also, the temperature inside the samples may not be higher
then the acid boiling point (usually about 110-120 ºC).

15. 15
Microwave-Assisted
Acid Digestion:
Microwave-assisted
acid digestion is a
relatively new
method of sample
digestion that has
gained popularity due
to its high efficiency
and accuracy. In this
method, the sample is
mixed with a strong
acid in a sealed
container and then heated using microwave radiation. The high pressure created inside the
sealed container made of Teflon or quartz glass raises the boiling temperature of the acid,
resulting in higher temperatures and faster digestion. This method is highly efficient and allows
for the digestion of a wide range of sample types, including organic and inorganic samples.
The resulting solution is then diluted with deionized water and analyzed by ICP-OES/MS. The
main advantage of microwave-assisted acid digestion over other digestion methods is its high
efficiency and accuracy. This method can digest samples in a fraction of the time required for
other digestion methods, while also improving the accuracy of the results.

16. 16
There are various types of laboratory microwave ovens available on the market, and it's
important to choose the appropriate sample digestion method and technique based on your
research requirements and budget.
Limit of Detection (LOD)
and Limit of Quantitation
(LOQ) are two important
figures of merit in
analytical chemistry that
are used to describe the
sensitivity of an
analytical method.
LOD is defined as the
lowest concentration of
an analyte that can be
reliably distinguished

17. 17
from the background signal, while LOQ is defined as the lowest concentration of an analyte
that can be reliably quantified with acceptable precision and accuracy.
In ICP analysis, LOQ of the instrument is the minimum concentration of an element that can
be detected by the ICP instrument with acceptable precision and accuracy. LOQ of the method,
on the other hand, takes into account all of the steps involved in the analysis, including sample
preparation and measurement, and represents the minimum concentration of an element that
can be reliably quantified with acceptable precision and accuracy using a particular method.
Sample digestion is an
important step in ICP
analysis, as it helps to break
down the sample matrix and
release the analyte of
interest for measurement.
Because of the simple fact
that the digestion of the
sample is, actually, the
dilution of this sample, this procedure increases the LOQ of the method, as it reduces the
concentration of the analyte in the original sample.
ICP-OES (Inductively Coupled
Plasma-Optical Emission
Spectrometry) and ICP-MS
(Inductively Coupled Plasma-Mass
Spectrometry) are multi-element
techniques widely used in analytical
chemistry for the simultaneous
determination of multiple elements in
a single sample. Despite being multi-
element techniques, different groups
of elements require slightly different measurement conditions due to their unique chemical and
physical properties.

18. 18
For example, some elements may have a lower ionization energy than others, which can result
in a lower sensitivity during measurement. Additionally, some elements may be prone to
forming polyatomic ions, which can lead to spectral interference and affect the accuracy and
precision of the analysis.
To address these differences, different measurement conditions are often used for different
groups of elements. For instance, some elements may require the use of specific ionization
buffers to improve sensitivity (applicable to AA techniques), while others may require different
wavelengths or integration times to minimize spectral interference (applicable to ICP-OES), or
the use of collision/reaction cells in ICP-MS to reduce interferences caused by polyatomic ions.
These are the elements that may be
routinely measurement in the Plasma
Spectrochemistry laboratory of the
Scientific Service Core Facility in
different matrices after the
appropriate sample preparation
procedure.
Although researchers at
our Faculty have not yet utilized
Speciation Analysis and Isotope
Ratio Analysis, these techniques
are available for us to use with the
instruments currently available in
the Scientific Service Core
Facility. However, additional
efforts in methods development
and validation are required.

19. 19
Speciation analysis is an important tool in environmental science to determine the
chemical form of an element in a sample. Hyphenated techniques, such as liquid
chromatography (LC) and capillary electrophoresis (CE) coupled with inductively coupled
plasma mass spectrometry (ICP-MS), have become popular for speciation analysis due to their
high sensitivity and selectivity.
In recent years, the
application of hyphenated
techniques with ICP-MS has
increased in environmental
science for the analysis of metal
species in complex environmental
samples. The coupling of LC or
CE with ICP-MS allows for the
separation and identification of
individual metal species in a
sample, providing more detailed
information than total metal analysis.
Hyphenated techniques with
ICP-MS have been used to
study metal speciation in
various environmental
matrices, such as water, soil,
sediment, and biological
tissues. In water, speciation
analysis is used to determine
the bioavailability and toxicity
of metals in aquatic
ecosystems. In soil and
sediment, speciation analysis is used to investigate the mobility and bioavailability of metals
in the environment, and to determine the potential risk to human health and the environment.

20. 20
In biological samples, speciation analysis is used to study the absorption, distribution,
metabolism, and excretion of metal species in the body. This information is crucial for
understanding the toxicity and potential health effects of exposure to metals.
One area where speciation analysis is particularly important is in environmental
science, where it can be used to distinguish between toxic and non-toxic forms of elements.
For example, in arsenic speciation, we can determine the presence of toxic inorganic arsenic
versus non-toxic organic forms. Similarly, in the case of chromium, we can differentiate
between toxic Cr VI and non-toxic Cr III forms.
Speciation analysis is particularly useful in the fields of soil, water, and plant sciences.
In soil science, it can help us understand the bioavailability and mobility of different elements,
which can have implications for plant growth and health. For example, knowing the speciation
of phosphorus in soil can help us determine its availability to plants. In water science,
speciation analysis can be used to determine the presence of harmful contaminants, such as
lead or mercury, and their potential impact on human and environmental health. In plant
science, speciation analysis can help us understand the uptake and transport of nutrients and
trace elements, which can have important implications for plant growth and crop yield.
Hyphenated techniques with ICP-MS have also been used to study the transformation
and transport of metal species in environmental systems. For example, they have been used to
study the transformation of
mercury species in aquatic
ecosystems and to investigate the
transport of metal species in rivers
and estuaries.
For additional information
please refer to the website:
www. speciation.net

21. 21
Another type of
analysis that should be
incorporated into our
research is isotope ratio
analysis using inductively
coupled plasma mass
spectrometry (ICP-MS) in
soil, water, and plant
sciences. Isotopes are
variants of the same element
that have a different number
of neutrons in the nucleus,
resulting in a slightly different atomic mass. Isotope ratio analysis allows us to measure the
relative abundance of different isotopes of an element in a sample.
There are two main types of ICP-MS instruments: Quadrupole ICP-MS and Multi-
Collector ICP-MS. Quadrupole ICP-MS is a more common and less expensive option, suitable
for measuring the isotope ratios of most elements. Multi-Collector ICP-MS, on the other hand,
is a more expensive and specialized instrument that can measure isotopes of elements with a
higher mass range, such as lead and uranium.
Isotope ratio analysis using ICP-MS has numerous applications in environmental
science. For example, measuring the isotopic ratio of lead (Pb) in soil and water can help us
distinguish between natural and anthropogenic sources of lead pollution. Anthropogenic
sources such as leaded gasoline, mining, and industry can have distinct isotopic signatures that
differ from natural sources such as geologic minerals.

22. 22
References
A WHITE PAPER FROM SPECTRO ANALYTICAL INSTRUMENTS. Comparing
ICP-OES Analyzers’ Plasma Interfaces: Axial, Radial, Dual, MultiView, and New Dual Side-
On
Website https://www.analytik-jena.com/
Materials of the European Winter Conference on Plasma Spectrochemistry, Ljubljana,
Slovenia, January 29th – February 3rd, 2023. https://ewcps2023.si/