🌟 Mass Spectrometry from Very Basics
✅ What is Mass Spectrometry?
Mass spectrometry (MS) is an analytical technique used to measure the mass-to-charge ratio (m/z) of molecules. It helps identify the chemical composition, structure, and quantity of compounds in a sample.
🎯 Why is Mass Spectrometry Important?
- Identifies unknown compounds
- Determines molecular weights
- Detects trace levels of substances
- Analyzes complex mixtures
- Studies structure and fragmentation of molecules
🔬 Basic Principle of Mass Spectrometry
Mass spectrometry involves three main steps:
- Ionization – Sample molecules are converted into ions.
- Separation – Ions are separated based on their mass-to-charge (m/z) ratio.
- Detection – The detector measures the ions and creates a mass spectrum.
🧪 Components of a Mass Spectrometer
| Part | Function |
|---|---|
| Sample Inlet | Introduces the sample (solid, liquid, or gas) |
| Ion Source | Converts molecules into ions (e.g., Electron Ionization) |
| Mass Analyzer | Sorts ions by their mass-to-charge ratio |
| Detector | Measures ion abundance and creates a signal |
| Vacuum System | Maintains low pressure to allow ions to move freely |
⚡ Ionization Methods
| Method | Description | Use |
|---|---|---|
| Electron Ionization (EI) | Electrons bombard the sample to knock out electrons | Organic molecules |
| Electrospray Ionization (ESI) | Produces ions by applying high voltage to liquid | Biomolecules (proteins, peptides) |
| Matrix-Assisted Laser Desorption/Ionization (MALDI) | Laser used to ionize large molecules | Proteins, polymers |
| Chemical Ionization (CI) | Uses reagent gas to ionize the sample | Softer than EI |
⚖️ Mass Analyzer Types
| Analyzer | How it Works | Example Use |
|---|---|---|
| Quadrupole | Filters ions using electric fields | Routine analysis |
| Time of Flight (TOF) | Measures time ions take to reach detector | Fast & accurate |
| Ion Trap | Traps ions and ejects by m/z | Detailed fragmentation |
| Orbitrap | Detects ions based on orbit frequency | High resolution |
| Fourier-Transform Ion Cyclotron Resonance (FT-ICR) | Very high resolution using magnetic fields | Research-grade accuracy |
📈 What is a Mass Spectrum?
A mass spectrum is a graph:
- X-axis: mass-to-charge ratio (m/z)
- Y-axis: relative abundance (intensity of signal)
Each peak represents a fragment or molecular ion.
🧩 Applications of Mass Spectrometry
- 🔍 Pharmaceuticals: Drug purity and identification
- 🧬 Proteomics: Protein sequencing
- 🌿 Environmental: Detecting pollutants
- 🧫 Clinical: Diagnosing diseases (e.g., cancer biomarkers)
- 🧪 Chemistry: Molecular structure determination
🔄 Bonus: Tandem Mass Spectrometry (MS/MS)
Used to fragment ions further for detailed structural info.
Two analyzers are used in sequence to analyze parent and daughter ions.
📚 Key Terms to Remember
- m/z: mass-to-charge ratio
- Base Peak: tallest peak in spectrum
- Molecular Ion (M⁺): peak representing intact molecule
- Fragment Ion: pieces of the molecule after ionization
🧠 Summary Chart
| Step | Description |
|---|---|
| 1. Ionization | Molecule → Ion |
| 2. Acceleration | Ions are given energy |
| 3. Separation | Ions separated by m/z |
| 4. Detection | Ions detected & counted |
| 5. Spectrum Output | Data visualized for analysis |
إرسال تعليق