Transmission quadrupole

LIT The linear ion trap (LIT) (also referred to as a two-dimensional, or 2D, trap) is a variation on the transmission quadrupole mass analyzer. In the LIT, the quadmpole is constructed such that either ions can be analyzed immediately or, ions can be trapped and held in the quadrupole region and then analyzed (Hager, 2002 Schwartz et al., 2002). Various types of MS/MS can be performed, as described in Chapter 3. 

FIGURE 3.11 Schematic diagram of a transmission quadrupole mass filter (a) and the way voltages are applied to it (h). 

Describe two methods for ionizing liquid samples for mass spectral analysis. Diagram a transmission quadrupole mass analyzer. What are the advantages and disadvantages of this mass analyzer compared with a double focus mass spectrometer ... 

The single quadrupole is one of the earliest mass analyzers to become widely available. A quadrupole separates ions according to their m/z ratio as a function of their trajectory through an oscillating electric field. With a transmission quadrupole mass analyzer, direct-current (DC) and radiofrequency (RF) voltages are applied to four parallel rods (Fig. 6.7a). As ions are accelerated through... 

An important configuration of quadrupoles is the triple quadrupole (QqQ), in which there are two analytical quadrupoles (Q) separated by a transmission quadrupole (q). While the predominant use of the QqQ is in quantification, this very versatile format has several scanning modes that enable multiple MS/MS approaches to obtain structural information (Section 3.3.3.1). Extensions of the quadrupole technology are the quadrupole ion trap (QIT) and the more recent linear ion trap (LIT) that has higher ion capacity. The resolutions of these ion traps are similar to those of single quadrupoles. However, an advantage of the traps is the ability to store and manipulate ions prior to their detection, thus enabling MS/MS experiments (Section 2.3.2). 

Figure 9.31 (a) Transmission quadrupole mass spectrometer. Rods A and B are tied together electrically, as are Rods C and D. The two pairs of rods, AB and CD, are connected both to a source of direct potential and a variable RF excitation such that the RF voltages are 180° out of phase, (b) The geometry of the rods, (c) Sequential detection of elements by peak hopping. 

Figure 21-11 shows a transmission quadrupole mass spectrometer, which is the most common mass separator in use today. It is connected to a gas chromatography column at the left to record the spectrum of each component as it is eluted. Compounds exiting the column pass through a heated connector into the ionization chamber where they are converted into ions and accelerated by 15 V before entering the quadrupole mass separator. 

Transmission quadrupole to which an oscillating radio frequency potential is applied so as to focus a beam of ions through a colhsion gas with no miz separation. 

A tandem mass spectrometer comprising two transmission quadrupole mass spectrometers in series, with a non-resolving (RF-only) quadrupole between them to act as a collision cell. 

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