Inductively Coupled Plasma Spectroscopy (ICP)
Introduction:
Inductively Coupled Plasma Spectroscopy is used to detect and quantify metallic elements. This method relies on exciting the electrons of various elements in a medium called plasma, and measuring the light emitted as the electrons relax. This technique can yield highly accurate results and is widely used for analyzing elements in soil, water, alloys, cosmetics and personal care products, animal and fish feed, agricultural products and food, detergents, air, pharmaceutical and medical products across a broad range of concentrations (ppm, ppb) simultaneously.
ICP-OES analysis, alongside ICP-MS, is considered one of the best analytical methods for determining the concentration of precious and heavy metals in soil, rock, and water samples in trace amounts. As a result, these methods are widely used in both industry and academic research. It is very important to note that the sample must be a clear solution. Therefore, to analyze solid samples, the solid material must be dissolved in a suitable solvent, often acids, through a process known as digestion.
Instrument Definition:
ICP-MS (Inductively Coupled Plasma Mass Spectrometry) is among the most accurate methods for measuring the concentration of elements in samples. This technique can detect amounts as low as parts per billion (ppb). Samples introduced into an ICP-MS instrument must be in liquid form or as a clear, single-phase solution free of suspended particles, which requires dissolving solid materials in a suitable solvent, a process referred to as digestion.
In the instrument, a defined volume of the liquid sample is sprayed into the plasma torch. The particles are ionized by the plasma generated using argon gas. The resulting ions are accelerated by an electric field and then separated in a magnetic field based on their mass-to-charge ratio. The instrument measures the concentration of each ion, enabling the analysis of up to 70 elements at once, including all metals, metalloids, and some non-metals.
Measuring very low concentrations of certain elements (below 100 ppm) using traditional methods is a complex task. In such cases, Inductively Coupled Plasma (ICP) or Optical Emission Spectroscopy (ICP-OES) is the preferred method. This technique can accurately measure up to 62 metals and seven non-metals down to 1 ppm, simultaneously.
This method is widely used for evaluating environmental pollution, including water and soil contamination and fuel analysis. It is important to note that the ICP instruments available in Iran require liquid samples, meaning solid samples must be dissolved in specific solvents. Therefore, identifying the full chemical composition of the solid material and the target elements is crucial to ensure accurate and reliable results.
Measurement Benefits:
1. Detection down to ppb levels
2. Measuring elements in extremely low concentrations (ppb) requires advanced techniques, including digestion of solid samples and accurate quantification of each element.
3. Interference Removal Technology (DRC) is used to reduce interferences from other elements and ensure accuracy.
4. Geological Applications: Measuring elements in soil, rock, and river sediment samples.
5. Environmental Applications: Trace metal analysis in water, food, plants, animals, soil, and sediments.
6. Biological and Clinical Applications: Measuring trace metals in clinical samples, blood products, and tissues.
7. Archaeological Applications: Analyzing ancient samples to determine chemical composition and age.
8. Industrial Applications: Measuring metals in industrial wastewater and sludge.
These applications highlight the importance of precise elemental analysis across diverse fields, contributing to better understanding of the environment, public health, and cultural heritage.
Analysis Conditions:
1. If samples are opaque solutions, the digestion option must be selected.
2. If the sample contains high levels of silicon or aluminum and these elements need to be measured, please notify us.
3. For the measurement of silicon, nitrogen, and chlorine, a larger sample volume is required.
4. No standard curve is provided.
5. The minimum reportable limit for liquid samples is around 10 ppb, and for solid samples, it ranges from 0.2 to 0.5 ppm. Exceptions may apply to certain elements, so please inform us at the time of request if necessary.
6. The cost includes measurement of all elements except for precious metals, which incur a separate fee.
Inductively Coupled Plasma (ICP) detectors:
They are widely used in analytical chemistry for elemental analysis. They are particularly effective for detecting metals and several non-metals in various samples. ICP detectors are powerful tools for elemental analysis, providing high sensitivity and the ability to analyze a wide range of elements in various sample types. The choice of detector depends on the specific analytical requirements, such as sensitivity, detection limits, and the nature of the sample being analyzed. Here are the main types of ICP detectors and their characteristics:
1. ICP Optical Emission Spectroscopy (ICP-OES)
Principle: Uses the light emitted by atoms and ions in a plasma to identify and quantify elements. The sample is introduced into the plasma, where it is atomized and excited, leading to the emission of light at characteristic wavelengths.
Applications: Commonly used for environmental analysis, food safety, pharmaceuticals, and materials science.
Suitable Compounds: Metals, metalloids, and some non-metals in solid, liquid, and gaseous samples.
2. Inductively Coupled Plasma Mass Spectrometry (ICP-MS)
Principle: Combines ICP with mass spectrometry to detect ions based on their mass-to-charge ratio. After ionization in the plasma, the ions are introduced into a mass spectrometer for analysis.
Applications: Used for trace element analysis, isotope ratio studies, and environmental monitoring.
Suitable Compounds: Trace metals, rare earth elements, and isotopes in various matrices, including biological tissues, environmental samples, and geological materials.
3. ICP Atomic Emission Spectroscopy (ICP-AES)
Principle: Similar to ICP-OES, it detects the light emitted from excited atoms after they are introduced into the plasma. It typically focuses on the analysis of elements in specific spectral lines.
Applications: Used in metallurgy, geology, and materials science for quantitative analysis.
Suitable Compounds: Primarily metals and some non-metals across a wide concentration range.
4. Laser Ablation ICP-MS (LA-ICP-MS)
Principle: Involves using a laser to ablate a small amount of material from a solid sample, which is then transported into the ICP for ionization and mass spectrometry.
Applications: Suitable for solid sample analysis, including geological samples, forensic analysis, and art conservation.
Suitable Compounds: Metals, metalloids, and some non-metals in solid matrices.
Types of Samples That Can Be Analyzed:
ICP-OES and ICP-MS techniques can be used to determine precise concentrations of metallic and non-metallic elements in:
1. Liquid Samples:
Drinking water
Wastewater
Chemical solutions
Food liquids (e.g., juices, milk)
2. Solid Samples:
Soil (from various regions)
Geological rocks
Water sediments (from rivers and lakes)
Building materials (e.g., concrete)
3. Biological Samples:
Plants (leaves, roots)
Animals (tissue, blood)
Food products (fruits, vegetables)
4. Archaeological Samples:
Artifacts made from various materials
Soil or sediments from archaeological sites
5. Industrial Samples:
Industrial wastewater
Industrial chemical materials
Result Analysis:
Accurate interpretation of results is a critical part of any chemical analysis. Here are the basic steps to help understand your results:
1. Understand Units of Measurement:
Ensure you recognize units such as ppb (parts per billion) or ppm (parts per million). Results are typically expressed as the concentration of elements in the sample.
2. Understand Standard Curves (if used):
Ensure results fall within the defined range, which helps assess measurement accuracy.
3. Compare with Standards:
Compare results with accepted standards or regulatory limits (local or international) to determine if sample concentrations exceed safe levels.
4. Check for Interferences:
If results are unexpected or inaccurate, verify potential interference from other elements. Known interfering elements can affect measurement accuracy.
If results are complex or need deeper interpretation, you are encouraged to consult experts at Photon Center.
Example of Result Interpretation:
If a result indicates that the concentration of a certain element is 20 ppb, and the acceptable limit is 10 ppb:
Result: 20 ppb
Permissible Limit: 10 ppb
Interpretation: The concentration exceeds the permissible limit, indicating potential contamination or environmental concern.