Isotope tracer and its application Nuclear Chemistry .pdf

Isotope related sheet

1. Abdul Wajed
ASH2314041M

2. what is isotope
An isotope is a variant of a chemical element that has the same number of protons
(and thus the same atomic number) but a different number of neutrons in its
nucleus.
Because the number of protons determines the element, isotopes of the same
element have nearly identical chemical properties but may differ in mass and some
physical or nuclear properties.
For example:
Hydrogen has 3 isotopes:
Protium (¹H): 1 proton, 0 neutrons
Deuterium (²H): 1 proton, 1 neutron
Tritium (³H): 1 proton, 2 neutrons

3. Types of Isotopes
They can also be classified into different types based on their stability, in the following
manner :
Stable Isotopes
These isotopes as the name suggests are stable for a long time and their nuclei do not
undergo spontaneous decomposition for a long time.
The spontaneous degradation of nuclei is known as radioactivity. The time taken for
radioactivity to reduce by half its existing value is known as half life of the element.
Stable isotopes have a long half life.
Primordial Isotopes
These types of isotopes have a half-life which is as old as the Earth with some having
existed before the formation of the Earth. Mostly all naturally occurring isotopes are
primordial isotopes as they have half life comparable to the age of the Earth.
Unstable Isotopes
Unstable isotopes are those with short half life.
They undergo radioactivity frequently, thus these they are radioactive in nature.
These isotopes undergo radioactivity and change into different stable elements.

4. Isotope Tracer (Definition)
An isotope tracer is an isotope (radioactive or stable) used as a marker to track the
movement, chemical reactions, or pathways of an element or compound within a
system . It behaves chemically like the normal element but can be detected due to
its radioactivity or distinct mass.

5. Types of Isotope Tracers
Radioactive Isotope
Tracers Emit radiation (alpha, beta, gamma).
Easily detected with radiation counters.
Examples:
Carbon-14for tracing carbon pathways in plants.
Iodine-131for thyroid function tests.
Technetium-99min medical imaging.
Stable Isotope
Tracers Non-radioactive but have different masses.
Detected using mass spectrometry.
Examples:
Carbon-13in metabolic studies.
Deuterium (²H) in water cycle research

6. .
Fig: Different Radio isotope

7. .
Principle of Isotope Tracers
1. Isotopes Behave Chemically the Same as the Element
1.All isotopes of an element have the same number of protons and electrons, so
they have nearly identical chemical properties.
2.This means if you substitute a normal atom with its isotope, it will participate in
reactions and pathways exactly like the original substance.
2.The Tracer “Labels” the Substance
1.When an isotope is incorporated into a molecule (e.g.,
14
??????-glucose), the
molecule still behaves normally in biological or chemical processes.
2.Because the isotope is detectable, it acts as a “tag” or “marker” to follow the
substance’s movement or transformation.
3.Detectable Difference Between Isotopes and Normal Atoms
1.Radioactive isotopes emit radiation (alpha, beta, or gamma rays) that can be
measured by counters or imaging techniques.
2.Stable isotopes (non-radioactive) differ in mass and can be detected using mass
spectrometry or isotope-ratio analyzers.

8. 4.Tracing the Pathway
By monitoring where the isotope appears (in tissues, products, or different
compartments), you can track:
Transport(how it moves)
Transformation(what reactions it undergoes)
Turnover rates(how fast it’s metabolized or replaced)
5.Quantitative Measurement
The intensity of radiation or the ratio of isotopes gives a quantitative measure of the
amount of tracer present. This allows scientists to calculate rates, efficiencies, and fluxes
in biological, chemical, or environmental systems.
6.Minimal Interference
Because only a tiny amount of isotope tracer is needed, the natural system is not
significantly disturbed —it’s like adding a colored dye, but invisible to the process
itself.

9. Preparation of Isotope Tracers
•Labeling of Molecules
–Incorporate radioactive or stable isotopes into specific positions of molecules
–Examples: C-14 in glucose, N-15 in amino acids
•Chemical Synthesis
–Use chemical reactions to attach isotopic labels to desired compounds
–Ensure isotopic substitution does not alter normal behavior
•Purification & Quality Control
–Remove unlabelledor partially labelled compounds
–Test for purity, specific activity, and stability
•Storage & Stability
–Store in appropriate containers (shielding if radioactive)
–Minimize degradation by light, heat, or contamination
•Safety Considerations
–Follow radiation safety protocols (if radioactive)
–Use gloves, fume hoods, and shielding as needed

10. Applications of Isotope Tracers in Agriculture
1. Improving Fertilizer Use Efficiency (N-15 Stable Isotope)
Using ^15N-labelled fertilizers helps track how much applied nitrogen is actually
taken up by crops versus what is lost or remains in the soil.
Example: In Myanmar, ^15N was used to evaluate rice varieties for their fertilizer
uptake, helping reduce over‐application and environmental loss
Biochar combined with N fertilizer improved ^15N retention in both soil and plant in
pakchoi; peak efficiency observed around 200 kg N/ha
•2. Quantifying Biological Nitrogen Fixation
•^15N isotope dilution technique allows scientists to estimate how much nitrogen is
obtained from the atmosphere (via nitrogen-fixing organisms) versus from soil/fertilizer.
This helps in assessing legume efficiency, BNF contribution, and managing fertilizer
inputs.

11. 3. Tracking Uptake & Distribution of Nutrients Under Different Fertilizer
Forms
•Studies using ^15N labelled forms assess uptake/translocation changes when using
nano vs conventional fertilizers.
•Example: Mango seedling studies: nano-Ca foliar application enhanced
translocation, uptake, and nitrogen use efficiency (NUE) compared to conventional
calcium applications when using ^15N tracer fertilizer.
4. Assessing Nutrient Cycling and Residue Contribution
•^15N tracers help understand how nitrogen from crop residues (shoots and roots)
travels through the soil and is taken up by subsequent crops, or retained in soil
organic pools.
•Example: cereal rye as a cover crop—very little of the residue nitrogen ended up in
following corn/soybean; majority remained in the soil organic pool

12. 5. Optimizing Timing and Splitting of Fertilizer Application
•Natural‐abundance ^15N studies can reveal how splitting nitrogen doses (e.g., late
application) improves nitrogen remobilization, final grain quality, and NUE in wheat
versus single large applications.
6. Applications Beyond Nitrogen: Other Isotopes & Tracers
•Use of ^32Pfor phosphorus uptake and soil–plant phosphorus dynamics; also
utilized in field & greenhouse experiments to study root activity and P fertilizer
performance
•Water movement studies: tritium (H-3)and deuterium (heavy hydrogen)tracers
are used to monitor how efficiently water is taken up, transpired, or lost in irrigation
systems and crop water use studies

13. Applications of Isotope Tracers in Environmental Studies
1. Tracking Water Movement and Groundwater Recharge
•Stable isotopes of hydrogen (²H/deuterium) and oxygen (¹⁸O) are used to trace the origin
and movement of water in rivers, lakes, and aquifers.
•Helps determine recharge zones, mixing between groundwater and surface water, and
evaporation rates.
•Example: δ¹⁸O and δ²H mapping used to study recharge sources in arid regions
(UNESCO/IAEA Water Isotope Program).
2. Identifying Sources of Pollution
•Nitrogen isotopes (δ¹⁵N) and oxygen isotopes (δ¹⁸O in nitrates) identify whether nitrate
pollution originates from fertilizer, sewage, or animal waste.
•Lead isotopes (²⁰⁶Pb/²⁰⁷Pb) or other heavy metals trace industrial pollution sources.
•Example: Tracing nitrate contamination in groundwater to agricultural vs. urban sources.

14. 3. Studying the Carbon Cycle
Carbon isotopes (¹³C and ¹⁴C) track carbon sources and sinks in the atmosphere, soils, and
oceans.
Useful for understanding soil organic matter turnover, climate change effects, and carbon
sequestration projects.
Example: Radiocarbon (¹⁴C) used to estimate age of groundwater or soil carbon pools.
4. Understanding Nutrient Cycling in Ecosystems
Nitrogen isotopes (¹⁵N) used to quantify denitrification, nitrogen fixation, and nutrient
pathways in rivers, wetlands, and coastal zones.
Phosphorus tracers and radioisotopes help understand sediment-water interactions in lakes.
5. Tracing Food Webs and Animal Migration
Stable isotope analysis (¹³C and ¹⁵N) reveals energy flow and trophic levels in food webs.
Strontium isotopes (⁸⁷Sr/⁸⁶Sr) in fish otoliths or animal tissues reveal migration patterns
and habitat use.
Example: Tracking salmon migration between ocean and river using isotopic fingerprints.

15. 6. Climate Change and Paleoenvironments
•Ice cores: ¹⁸O/¹⁶O ratios reconstruct past temperatures.
•Sediment cores: Carbon and nitrogen isotopes track historical productivity and pollution.
7. Oil Spills and Contaminant Forensics
•Compound-specific isotope analysis (CSIA) distinguishes between petroleum products or
detects degradation of contaminants.
•Used to determine whether cleanup or natural attenuation is occurring.

16. 1. Studying Metabolic Pathways
•(¹⁴C) and Hydrogen-3 used to label metabolites (e.g., glucose, amino acids) to follow their
transformation in cells.
•Reveals pathways such as glycolysis, Krebs cycle, and lipid metabolism.
•Example: Using ¹⁴C-labelled glucose to study insulin’s effect on glucose uptake.
2. Protein and Nucleic Acid Synthesis
•Incorporation of ³H-thymidine to track DNA replication.
•³H-leucine or ³H-uridine used to monitor protein or RNA synthesis rates.
•Vital in cell biology, cancer research, and drug testing.
3. Drug Development and Pharmacokinetics
•Isotopic labeling of drugs helps measure absorption, distribution, metabolism, and excretion
•Allows detection of very low concentrations in blood/tissues.
•Example: Using deuterium-labeled compounds to study drug half-life.
Applications of Isotope Tracers inBiology & Medicine

17. 4. Diagnostic Imaging (Nuclear Medicine)
•Positron Emission Tomography (PET): Uses positron-emitting isotopes like ¹⁸F ,¹¹C, ¹³N, ¹⁵O to
visualize metabolic activity.
•Single Photon Emission Computed Tomography (SPECT): Uses gamma-emitting tracers like
Technetium-99m (⁹⁹ᵐTc).
•Applications: Cancer detection, brain mapping, cardiac perfusion, bone scans.
5. Measuring Hormone or Receptor Binding
•Radiolabeled hormones or ligands used in receptor-binding assays to study endocrine function.
•Example: ¹²⁵I-labelled insulin to measure receptor density on cell membranes.
6. Vitamin & Mineral Metabolism
•Calcium-45 and Iron-59 track mineral absorption and turnover.
•Zinc isotopes used to study zinc kinetics in humans.
7. Tumor and Cell Proliferation Studies
•³H-thymidine autoradiography measures cell proliferation rates in cancer tissue.
•Helps in evaluating treatment response or aggressiveness of tumors.

18. Applications of Isotope Tracers in Chemistry
1. Elucidating Reaction Mechanisms
•Isotopic labeling (using ¹³C, ¹⁵N, ²H/deuterium, ¹⁸O) reveals the path atoms take during a
chemical reaction.
•Detects which bonds break or form and identifies intermediates.
•Example: Using deuterium substitution to identify the rate-determining step in
hydrogenation.
2. Studying Reaction Kinetics and Isotope Effects
•Kinetic Isotope Effect (KIE): Change in reaction rate when an atom is replaced by its isotope
(e.g., H → D).
•Helps deduce transition states and bond strengths.
3. Determining Molecular Structure
•Nuclear Magnetic Resonance (NMR):–¹³C and ²H isotopic enrichment improves signal
clarity and structure determination. , aiding assignment of functional groups.
•Isotopic substitution changes vibrational frequencies in IR spectroscopy

19. 4. Following Chemical Pathways
•Used in inorganic, organometallic, and surface chemistry to see how ligands or substrates
bind and exchange.
•Example: ¹⁸O-labelled water to study oxygen incorporation in metal-oxo complexes.
5. Analytical Chemistry and Calibration Standards
•Stable isotopes provide precise internal standards in mass spectrometry.
•Allows accurate quantification of trace compounds in complex mixtures.
6. Investigating Environmental and Industrial Chemistry
•Tracing pollutants or chemicals in air and water using isotopic signatures (e.g., sulfur,
chlorine, lead).
•Understanding corrosion pathways, reaction intermediates, and catalytic processes in
industrial systems.
7. Teaching and Demonstration
•Safe stable isotopes used in labs to show chemical processes to students without risk.
•Provides a hands-on tool to visualize abstract concepts like reaction paths or equilibrium
shifts.