A

amu

Atomic mass unit, general unit of measurement for relative atomic and molecular masses.

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C

Chromatography

Wide-spread separation technique used in analytics and is based on the distribution equilibrium between a stationary and a mobile phase. The mobile phase can be gaseous (gas chromatography, GC) or liquid (liquid chromatography, LC or HPLC).

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F

Faraday detector, Faraday cup

Ion detector that converts the charge of all caught ions directly into an electric current.

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H

HF generator

High-voltage generator for high-frequency alternating voltage required to generate a quadrupole field. The HF generator also supplies the required voltages for separating the individual masses.

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M

m/z value

Ratio of the mass unit and the charge number of a given ion. The m/z value represents the x-axis of a mass spectrum. As the charge number z is usually equal to 1, the x-axis of the mass spectrum can be used to read the mass unit of the given ion.

Mass filter, mass analyzer

The part of the mass spectrometer that filters the given ions based on their m/z value. Electric and/or magnetic fields or high-frequency electromagnetic oscillating fields for example are used for this purpose.

Mass number

Another name for relative atom and molecular masses, some examples:
Helium He - mass number 4
Carbon C - mass number 12
Molecular nitrogen N2 - mass number 28
Atomic nitrogen N - mass number 14
Molecular oxygen O2 - mass number 32
Atomic oxygen O - mass number 16
Water H2O - mass number 18
Carbon dioxide CO2 - mass number 44

Mass spectrometry (MS)

Universal measurement method for qualitative and quantitative analysis. The principle is based on the physical determination of the particle mass of molecules and molecule fragments under vacuum in a mass analyzer. The molecules are electrically charged (ionized) in an ion source. Mass spectrometry is used, amongst other things, for elucidating the structure of unknown chemical compounds, determining and quantifying substances in material mixtures and for element and isotope analysis. Mass spectrometers are often coupled with gas chromatography or other separation techniques to improve performance capabilities. They are however also used as process mass spectrometers for direct and continuous measurement (online analysis) of material mixtures.

Mass spectrum

Plot of the intensity of the ions formed from the sample (Y axis) dependent on the m/z value of the ions (X axis).

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O

Online gas analysis

In this process analysis measurement technique, gases and gas mixtures are taken directly and continuously from the production process (bypass) and immediately analyzed online where possible. The measuring instrument is either integrated into the system or is located directly next to it. The measurement results can be automatically transmitted to the process control system. A process mass spectrometer can be used with typical measurement cycle times of approximately 1 second to provide process control with essentially real-time material concentration measurements.

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P

Process mass spectrometer

These are online analysis systems for process analysis, usually used for production control and monitoring, quality control and process development on the basis of quadrupole mass spectrometers for fully automatic concentration determination of gases and gas mixtures (online gas analysis). The mass spectrum analysis procedure (mass spectrometry) is highly selective and sensitive. With measurement cycle times in the region of seconds, it is an excellent online measurement technique for rapid multi-component analysis.

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Q

Quadrupole

Name for mass filters based on high-frequency oscillating fields (quadrupole fields).

Quadrupole mass spectrometer

In quadrupole mass spectrometers, the separation and determination of the molecule and fragment masses is implemented with high-frequency oscillating electric fields (HF). The HF voltages required for this are generated under vacuum on four rod-shaped electrodes (quadrupole). The filtering and determination of the ionized molecules is then implemented with a programmed modulation in the amplitude of the HF voltage with simultaneous superimposition of a direct current voltage which can also be modulated.

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R

Rod system

Parallel arrangement of (four) rod-shaped electrodes between which a quadrupole field is set up. The selected ions with a specific m/z value travel on a stable trajectory through the rod system from the ion source to the detector, generating a corresponding signal. All other ions are deflected by the quadrupole field and do not reach the detector. Different m/z values can be set extremely rapidly (milliseconds) and reliably with a quadrupole field.

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S

SEM (Channeltron)

Secondary electron multiplier, particle and ion detector for mass spectrometry with high measurement speed and sensitivity.

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