Detectors commonly used in mass spectrometry systems

A key factor in all mass spectrometry systems is the type of detector used to convert the current from mass-separated ions into a measurable signal. Different types of detectors are employed depending on factors such as dynamic range, spatial information retention, noise and suitability for the mass analyser.

Commonly used detectors include:

· Electron multiplier (EM): A series connection of discrete metal plates that amplifies the ion current by approximately 10⁸ times, converting it into a measurable electron current.

· Faraday cup (FC): Ions striking the collecting electrode cause electrons to flow from ground through a resistor; the resulting potential drop across the resistor is amplified.

· Photomultiplier-conversion diode: Ions initially strike a diode, causing electron emission. The resulting electrons then strike a fluorescent screen, which in turn emits photons. The photons then enter a multiplier, where they are amplified in a cascaded manner—much like an EM.

· Array detectors (including detectors that simultaneously measure several ions with different m/z values and position-sensitive ion detectors): these encompass a wide range of detector types and systems, and can combine multiple detection techniques.

Mass spectrometers combined with other techniques

Gas and liquid separation techniques are frequently combined with mass spectrometry to enhance sensitivity and facilitate interpretation. Liquid chromatography (LC), gas chromatography (GC), capillary electrophoresis (CE) and gel electrophoresis (GE) are common examples. The combination of these methods is particularly common when used in tandem with ICP-MS and DART-MS.