WHAT IT IS
Detector type is the kind of ion detector used in a mass spectrometer to convert incoming ions into an electrical signal for measurement. Different detectors are suited to various applications, depending on the required sensitivity, speed, and precision. Common types include electron multipliers, Faraday cups, and microchannel plates.
TYPES OF DETECTORS IN MASS SPECTROMETRY
1. Electron Multiplier (EM) Detectors
Function: Amplifies ion signals by generating a cascade of secondary electrons when ions strike a surface.
Best for: High-sensitivity applications, low-abundance ion detection, and trace-level analysis.
Advantages: Extremely high sensitivity, capable of detecting single ions. Fast response time, ideal for high-throughput analysis.
Limitations: Limited lifespan due to degradation over time. Prone to noise at very low signal levels.
2. Faraday Cup Detectors
Function: Measures ion current by collecting ions directly and converting their charge into an electrical signal.
Best for: Applications requiring high precision and a wide dynamic range.
Advantages: Excellent long-term stability and durability. Wide dynamic range, suitable for measuring both low- and high-intensity signals.
Limitations: Lower sensitivity compared to electron multipliers. Slower response time, making it less effective for high-speed data collection.
3. Microchannel Plate (MCP) Detectors
Function: Uses an array of microscopic channels to amplify ion signals through secondary electron emission.
Best for: Time-of-flight (TOF) mass spectrometry, imaging applications, and high-speed data acquisition.
Advantages: High spatial and temporal resolution. Fast response time, enabling rapid data collection.
Limitations: Susceptible to degradation over time. Higher cost and maintenance requirements.
4. Daly Detectors
Function: Converts ions into secondary electrons, which are then detected using a photomultiplier tube (PMT).
Best for: Applications requiring extreme sensitivity and precision.
Advantages: Extremely high sensitivity, even for ultra-low ion intensities. Long operational life compared to electron multipliers.
Limitations: Requires specialized calibration and maintenance. Not as widely used as EM or Faraday cups.
5. Charge-Coupled Device (CCD) and Complementary Metal-Oxide-Semiconductor (CMOS) Detectors
Function: Converts ion signals into optical signals and processes them digitally.
Best for: Imaging mass spectrometry and high-resolution analysis.
Advantages: High resolution and efficient digital signal processing. Ability to capture spatially resolved mass spectra.
Limitations: Expensive and complex to integrate. Requires advanced computational processing.