Mass Spectrometry – Comprehensive Guide
Mass Spectrometry – Comprehensive Guide
What is Mass Spectrometry (MS)?
Mass spectrometry is a Technique used to identify and quantify the chemical composition of a compound with the help of molecular weight . It will be detected by mass to charge ratio and it is denoted by (m/e or m/z). Solid, Liquid and Gas molecule all three states sample can be evaluated by Mass Spectrometry.
How Mass Spectrometry works ?
Mass spectrometry works by ionizing the sample molecules and then accelerating, separating and detecting the ions by the mass analyzers based on their mass-to-charge ratio.
It is based on the principle that different compounds have different masses and mass to charge ratios. The sample is ionized by a variety of methods, such as electron impact, electrospray ionization, or matrix-assisted laser desorption. The ions produced are then separated based on their mass-to-charge ratio (m/z or m/e) using an analyzer, and the resulting mass spectrum is recorded. Mass spectrometry can provide information on the identity, quantity, and structure of the molecules in a sample with the help of molecular weight.
Components of Mass Spectrometry (MS)
Major Basic Components of Mass Spectrometry are enlisted as below,
- Sample vaporization chambers: These chambers are used to vaporize solid or liquid samples and convert them into a gas that can be analyzed by the mass spectrometer. Different techniques are used depending on the type of sample, such as laser ablation for solid samples and electrospray ionization for liquid samples.
- Ionization chambers: These chambers are used to ionize the sample molecules by bombarding them with high-energy particles such as electrons.
- Ion acceleration chambers: These chambers are used to accelerate the ions to high speeds using an electric field.
- Mass analyzer with magnetic field: Mass analyzers use a magnetic field to separate the ions based on their mass-to-charge ratio. This is known as a magnetic sector mass analyzer and is often used in combination with other types of mass analyzers.
- Detector: The detector is responsible for detecting the ions that have been separated by the mass analyzer and generating a signal. Different types of detectors are used depending on the type of ion being analyzed. For example, a Faraday cup detector may be used for stable ions, while an electron multiplier detector may be used for more unstable ions.
- Electric Amplifier: The electric amplifier is used to amplify the signal generated by the detector. This is necessary because the signal generated by the detector is usually very weak and needs to be amplified in order to be analyzed accurately.
- Recorder: The recorder is used to record the amplified signal generated by the detector. The recorded data can then be analyzed using specialized software to identify the different types of ions present in the sample.
Different Types of mass analyzers used in Mass Spectrometry (MS):
Mass spectrometry uses various types of mass analyzers to separate ions based on their mass-to-charge ratio. Some of the most commonly used mass analyzers are as :
- Magnetic field deflecting mass analyzer: This type of mass analyzer uses a magnetic field to deflect ions, allowing them to be separated based on their mass-to-charge ratio. It is often used in combination with other types of mass analyzers.
- Double focusing mass analyzer: This type of mass analyzer uses both magnetic and electric fields to focus and separate ions based on their mass-to-charge ratio. It is known for its high resolution and is often used in research applications.
- Quadrupole mass analyzer: This type of mass analyzer uses four parallel rods to separate ions based on their mass-to-charge ratio. It is compact and relatively inexpensive, making it a popular choice for many applications.
- Time-of-flight mass analyzer: This type of mass analyzer separates ions based on their time-of-flight through a flight tube. It is known for its high sensitivity and speed and is often used in proteomics and metabolomics research.
- Fourier transform ion cyclotron resonance (FTICR) mass analyzer: This type of mass analyzer uses a combination of magnetic and electric fields to trap ions and measure their mass-to-charge ratio. It is known for its high resolution and is often used in research applications.
The selection of mass analyzer depends on specific application and requirements of the analysis. Each type of mass analyzer has its own strengths and weaknesses, and selection of the appropriate analyzer is important for achieving accurate and precise results.
Applications of Mass Spectrometry (MS) :
Mass spectrometry used in pharmaceutical industry for identify and quantify the molecular mass and chemical composition of a compound it can be used to Identity and purity test of pharmaceutical substances i.e Trace analysis. It also used to monitor drug metabolism, assess drug stability, and analyze impurities
Advantages of Mass Spectrometry (MS)
There are several advantages of mass spectrometry, Some of the enlisted as below ,
- High sensitivity: Mass spectrometry can detect trace amounts of compounds in a sample.
- High specificity: Mass spectrometry can distinguish between compounds with similar chemical structures.
- Structural information: Mass spectrometry can provide information on the chemical structure of a compound.
- Quantitative analysis: Mass spectrometry can be used for quantitative analysis of compounds in a sample.
Types of Ionization Techniques in Mass Spectrometry (MS) :
In mass spectrometry, there are two main types of ionization techniques: hard ionization and soft ionization. The choice of ionization technique depends on the sample and the information required from the analysis.
Hard Ionization Techniques: High Energy will be involved, Number of fragmented ions will be more and Number of Molecular ions will be less. Basically use high-energy sources to ionize molecules , resulting in the formation of highly energetic and fragmented ions. These techniques are useful for the analysis of volatile and stable compounds, but are not suitable for the analysis of large biomolecules Hard ionization techniques are typically used in gas chromatography-mass spectrometry (GC-MS) applications.
Soft Ionization Techniques: Less Energy required, Less fragmentation and Number of Molecular ions will be more .Basically use formation of less energetic and less fragmented ions. Soft ionization techniques are particularly useful for the analysis of large biomolecules such as proteins and nucleic acids, which can be difficult to analyze using hard ionization techniques. Soft ionization techniques are commonly used in liquid chromatography-mass spectrometry (LC-MS) applications.
Different Methods of Ionizations in Mass Spectrometry (MS) :
In mass spectrometry, there are various methods of ionization used to generate ions from a sample. Here are three different ionization Techniques:
- Gaseous Ionization: Gaseous ionization techniques is the oldest and most popular method. in this ionization technique Sample is vaporized before Ionization and use a high-energy gas to ionize molecules. It is further categorized in two parts Electron ionization (EI) and Chemical Ionization (CI)
- Desorption Ionization: In this Technique Solid sample are directly converted in to gaseous. it will use laser or other high-energy source to expel and ionize molecules from a solid sample. It is further categorized in three parts parts 1) Matrix-assisted laser desorption/ionization (MALDI) 2) Fast Atom Bombardment (FAB) 3) Field Desorption
- Evaporative Ionization: solvent molecules are removed by evaporations and ions will be produced. This techniques are specially used in Chromatography. It is further categorized as 1) Thermospray ionization 2) Electrospray ionization 3) Atmospheric pressure chemical Ionization (APCI) 4) Atmospheric pressure photo Ionization (APPI)
