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JP-7855852-B2 - Discharge ionization detector and gas chromatograph analyzer

JP7855852B2JP 7855852 B2JP7855852 B2JP 7855852B2JP-7855852-B2

Inventors

  • 宮内 真二
  • 品田 恵

Assignees

  • 株式会社島津製作所

Dates

Publication Date
20260511
Application Date
20211125

Claims (7)

  1. A dielectric tube extending in the axial direction of the tube, which constitutes at least a part of the gas flow path through which the discharge gas flows, A high-voltage electrode provided on the outer wall of the dielectric tube, A grounding electrode unit provided on the outer wall of the dielectric tube, which is electrically grounded, A voltage application unit is connected to the high-voltage electrode and applies an AC voltage between the high-voltage electrode and the ground electrode unit in order to generate a discharge in the dielectric tube and generate plasma from the discharge gas, The system includes a charge collection unit which includes a collection electrode that collects ions generated from sample components in a sample gas by light emitted from the plasma, The charge collection unit includes an opening for introducing the sample gas into the gas flow path, The opening is one end of the sample introduction tube that supplies the sample gas to the gas flow path. The shielding portion is located between the dielectric tube and the opening in the direction through which the discharge gas flows, and is located downstream of the dielectric tube, and further shields at least a portion of the opening from the dielectric tube . The shielding portion is a discharge ionization detector that shields at least a portion of the light reaching the aperture at a plane intersecting the extending direction of the sample introduction tube .
  2. A dielectric tube extending in the axial direction of the tube, which constitutes at least a part of the gas flow path through which the discharge gas flows, A high-voltage electrode provided on the outer wall of the dielectric tube, A grounding electrode unit provided on the outer wall of the dielectric tube, which is electrically grounded, A voltage application unit is connected to the high-voltage electrode and applies an AC voltage between the high-voltage electrode and the ground electrode unit in order to generate a discharge in the dielectric tube and generate plasma from the discharge gas, The system includes a charge collection unit which includes a collection electrode that collects ions generated from sample components in a sample gas by light emitted from the plasma, The charge collection unit includes an opening for introducing the sample gas into the gas flow path, The opening is one end of the sample introduction tube that supplies the sample gas to the gas flow path. The shielding portion is located between the dielectric tube and the opening and further shields at least a portion of the opening from the dielectric tube, A discharge ionization detector wherein the shielding portion shields at least a portion of the light reaching the aperture with a plane that intersects the extending direction of the sample introduction tube, thereby preventing the aperture from being irradiated with light emitted from the plasma.
  3. The discharge ionization detector according to claim 1 or 2, wherein the shielding portion is configured to shield the entire opening from the dielectric tube.
  4. The discharge ionization detector according to any one of claims 1 to 3, wherein the shielding portion is configured to shield the entire opening and its outer edge from the dielectric tube.
  5. The discharge ionization detector according to any one of claims 1 to 4, wherein the shielding portion has a member disposed between the dielectric tube and the opening.
  6. The aforementioned charge collection unit is A bias electrode for forming a DC electric field in the gas flow path to promote ion movement, A discharge ionization detector according to any one of claims 1 to 5, further comprising a guard electrode disposed between the collection electrode and the bias electrode and grounded.
  7. A discharge ionization detector according to any one of claims 1 to 6, An analytical column for separating the sample components in the sample gas into individual components, A gas chromatograph analyzer comprising a channel for introducing sample components separated by the analytical column into the gas channel of the discharge ionization detector.

Description

This invention relates to a discharge ionization detector and a gas chromatograph analyzer. Dielectric Barrier Discharge Ionization Detectors (BIDs) are used as trace gas detectors for gas chromatography (GC). Dielectric barrier discharge (BIDs) utilize a dielectric barrier discharge where the electrode surface is covered with a dielectric material (see, for example, Patent Document 1). In a BID, sample components in the sample gas are ionized by excitation light, and the ionized sample components are collected by the electric field generated by the sample detection electrode. The amount of the sample component is then detected based on the current flowing between the electrodes. Japanese Patent Publication No. 2010-060354 This figure shows an example of the configuration of a gas chromatograph analyzer according to this embodiment.This figure shows an example of how the sensitivity of a typical discharge ionization detector changes in response to changes in the concentration of a sample component.This is a diagram showing an example of the structure of the shielding plate 190.This is a diagram showing a first modified example of the shielding plate 190.This diagram shows a second modified example of the shielding plate 190.This figure shows a first comparative example of the shielding plate 190.This figure shows a second comparative example of the shielding plate 190.This figure illustrates an example of the change in sensitivity in the discharge ionization detector 10.This figure illustrates another example of the change in sensitivity in the discharge ionization detector 10.This figure illustrates yet another example of the change in sensitivity in the discharge ionization detector 10.This figure shows another example of the configuration of a gas chromatograph analyzer. The embodiments of this disclosure will be described in detail below with reference to the drawings. Parts identical or corresponding to those shown in the drawings are denoted by the same reference numerals, and their descriptions will not be repeated. [1. Configuration of a gas chromatograph analyzer] Figure 1 shows an example of the configuration of a gas chromatograph analyzer according to this embodiment. As shown in Figure 1, the gas chromatograph analyzer includes a discharge ionization detector 10, a sample introduction unit 34, and an analysis column 36. The gas chromatograph analyzer transports the sample to the sample introduction section 34 using a carrier gas, and then transports the sample to the analysis column 36. The analysis column 36 separates the sample components in the sample gas. The gas chromatograph analyzer then introduces the separated sample components into the gas flow path of the discharge ionization detector 10. The discharge ionization detector 10 is a detector for detecting sample components. The discharge ionization detector 10 comprises a dielectric tube 111, a high-voltage electrode 112, a ground electrode 113, a ground electrode 114, a voltage application unit 115, a control unit 22, and a light source 23. In one implementation example, the dielectric tube 111 has a cylindrical shape. The voltage application unit 115 functions as a power source for high-voltage AC power for excitation. The ground electrodes 113 and 114 are arranged spaced apart from each other in the axial direction of the dielectric tube, forming a ground electrode unit. The dielectric tube 111 forms a gas flow path through which the discharge gas (also referred to as the "plasma generation gas") flows, and extends in the axial direction of the tube. The plasma generation gas can be, for example, one of the following: helium (He), argon (Ar), nitrogen (N2), neon (Ne), xenon (Xe), or a mixture thereof. For the sake of explanation, in the following, the upstream side of the gas flow direction within the dielectric tube 111 (indicated by the downward arrow in Figure 1) will be defined as "up," and the downstream side as "down." However, these definitions are for convenience only and do not limit the direction in which the BID can be used. On the outer wall surface of the dielectric tube 111, annular electrodes (high-voltage electrode 112, ground electrode 113, and ground electrode 114) made of a conductive material such as SUS or copper are arranged around it along the direction of gas flow described above. The high-voltage electrode 112, ground electrode 113, and ground electrode 114 are sometimes collectively referred to as "plasma generation electrodes." The high-voltage electrode 112 is connected to the voltage application unit 115 and is provided on the outer wall of the dielectric tube 111. The grounding electrodes 113 and 114 are electrically grounded and are also provided on the outer wall of the dielectric tube 111. The high-voltage electrode 112 is provided between the grounding electrodes 113 and 114. The voltage application unit 115 applies an AC voltage between the high-voltage electrode 112 and the ground electrodes 113 an