What is a quadrupole in mass spectrometry?
What is a quadrupole in mass spectrometry?
As the name implies, it consists of four cylindrical rods, set parallel to each other. In a quadrupole mass spectrometer the quadrupole is the mass analyzer – the component of the instrument responsible for selecting sample ions based on their mass-to-charge ratio (m/z).
What is the resolution of a quadrupole mass filter?
The quadrupole mass filter is operated with 1 MHz main RF power and in the normal mode it is set to transmit ions of mass 609 Da with a theoretical resolving power of 10,000.
How does a Qtof MS work?
The Q-TOF MS uses a quadrupole (four parallel rods arranged in a square formation), a collision cell, and a time of flight unit to produce spectra. Lighter ions accelerate faster down the flight tube to the detector, thus determining the ions’ mass-to-charge ratios.
What is the notable advantage of the quadrupole mass spectrometer?
Quadrupole mass analyzers have several advantages such as no requirement for very high vacuum (> 10−7 Torr), and their relatively fast and simple operation for high-throughput analysis. Disadvantages include low transmittance, a low m/z cutoff, and low (generally unit) resolution.
How does a quadrupole mass Analyser work?
This type of mass analyzer separates ions based on the stability of their flight trajectories through an oscillating electric field in the quadrupole. The field is generated when a radio frequency (RF) voltage is applied between one pair of opposing rods within the quadrupole.
What do you mean by electric quadrupole?
[i¦lek·trik ′kwä·drə‚pōl] (electricity) A charge distribution that produces an electric field equivalent to that produced by two electric dipoles whose dipole moments have the same magnitude but point in opposite directions and which are separated from each other by a small distance.
How a quadrupole ion trap differs from a quadrupole mass filter?
An important distinction between quadrupole mass analyzers and quadrupole ion trap mass analyzers is that quadrupole mass analyzers separate and detect masses by allowing oscillating ions to pass through the quadrupole to reach the detector (beam-type mass analyzer), whereas quadrupole ion trap mass analyzers separate …
What is the difference between TOF and QTOF?
Single stage TOF instruments measure the accurate mass of all ions entering the flight tube. Addition of a quadrupole and a collision cell to a TOF forms a QTOF, a more expensive instrument that is able to isolate and fragment specific ions, as well as measure accurate mass.
What is the difference between single quadrupole and triple quadrupole?
Single quadrupole systems contain only one mass filtering quadrupole while triple quadrupole systems consist of three quadrupoles. During a mass scan, DC and RF voltages are ramped resulting in the acquisition of full scan mass spectra. Such spectra are typically used for qualitative data analysis.
Which analyzer is more significant TOF or quadrupole?
The advantages of time-of-flight mass analyzers compared to quadrupoles are clear. Samples can be measured faster and with no spectral skewing. For the same mass range, a TOF analyzer will measure each ion more sensitively.
How does a quadrupole ion trap work?
The quadrupole ion trap (linear of 3D) uses a quadrupole electric field to confine ions to particular space (Todd, 1991; Ghosh, 1995; March, 2005). The mass-to-charge ratio of the ions is then measured by applying an auxiliary electric field that excites a specific mass.
How does a quadrupole mass analyzer perform mass selection?
The mass spectrum is scanned by varying V0 and U so that the ratio U/V0 remains constant. The quadrupole mass analyzer acts as a mass filter, allowing one mass channel at a time to reach the detector as the mass range is scanned.
What is a quadrupole mass spectrometer filter system?
The filter system of a quadrupole mass spectrometer consists of four parallel rods arranged in the form of a square. Each pair of opposite rods in Figure 6.5, designated (+) or (-), is connected to each other.
How does the quadrupole field work?
The applied quadrupole field deflects the ions in the X and Y directions, causing them to describe helical trajectories around the Z axis through the mass filter.
What is the slope of the load line of the mass filter?
Dividing the two equations by one another gives: a / q = 2 U / V. This is the slope of the so-called load line of the mass filter. At the limit the load line intersects the peak with the values: a p = 0.237 and q p = 0.706. The quadrupole filter is transparent only for voltage ratios U V = a p 2 ⋅ q p < 0.1678
What is the relationship between mass and resolution in QMS?
This means that resolution increases proportionally to the mass number. Due to Formula 6-9 ( V is proportional to M) the quadrupole (as opposed to the sector field mass spectrometer) produces a linear mass scale. One point of major significance for a QMS is the required RF power.
