JP4833708B2 - Atmospheric pressure ionization method and sample holding device - Google Patents

Description

  The present invention relates to an ionization method used for an atmospheric pressure ion source and a sample holding device therefor.

  Various methods are known as atmospheric pressure ionization methods. Recently, an atmospheric pressure ionization method called DART (Direct Analysis in Real Time) (US registered trademark) has attracted attention. In this method, excited molecules generated by corona discharge or glow discharge are reacted with a sample, the sample is ionized, and introduced into an ion inlet (hereinafter referred to as an orifice) of a mass spectrometer.

  The principle diagram of DART is shown in FIG. DART is composed of three rooms. First, the first chamber 1 has a role of generating excited molecules by corona discharge or glow discharge. A gas introduction pipe 4 for introducing a gas such as helium, neon, or nitrogen is connected to the first chamber 1 so that the first chamber 1 can be filled with the gas.

The partition 6 (counter electrode) between the first chamber 1 and the second chamber 2 is set to the ground potential, and the corona between the needle electrode 5 attached to the first chamber 1 and the partition 6 is set. Discharge or glow discharge can be caused. For example, the ground singlet molecular helium gas (1 ¹ S) introduced into the first chamber 1 by this corona discharge or glow discharge is excited by helium ions He ⁺ , electrons e ⁻ , and 19.8 eV. It changes to a mixture of triplet molecules He (2 ³ S).

A partition 7 (perforated disk electrode) between the second chamber 2 and the third chamber 3 is set to about 100 V, and a potential gradient is provided between the second chamber 2 and the ground potential partition 6. In the second chamber 2, helium ions He ⁺ and electrons e ⁻ generated in the first chamber 1 are blocked, and only the neutral excited triplet molecule He (2 ³ S) is allowed to pass through. Helium ions He ⁺ are reflected by the partition 7, and electrons e ⁻ are absorbed by the partition 7.

The excited triplet molecule He (2 ³ S) that has passed through the second chamber 2 is heated in the third chamber 3 by a heater (not shown). This heating is performed for the purpose of assisting vaporization and thermal desorption of the sample 9 placed in the subsequent stage. The sample 9 may be solid or liquid.

  The outlet 8 of the third chamber 3 is a grid electrode, and a voltage of about 250 V is applied. On the other hand, since a voltage of about 30 V is applied to the orifice 10, a negative potential gradient is generated from the outlet portion 8 of the third chamber 3 toward the orifice 10.

The neutral excited triplet molecule He (2 ³ S) heated in the third chamber 3 reacts with water molecules in the atmosphere to penning ionize the water molecules. The water molecule positive ions form water cluster positive ions with water in the atmosphere, and further react with the sample 9 to generate sample ions MH ⁺ in which protons H ⁺ are added to the sample molecules M. FIG. 2 shows the mechanism.

The positive ions MH ⁺ generated by the mechanism of FIG. 2 are sucked into the orifice 10 in accordance with the negative potential gradient generated from the outlet 8 of the third chamber 3 toward the orifice 10, and mass analysis is performed by a mass spectrometer (not shown). Is made.

  In this example, positive ions are generated. However, when negative ions are generated, it is necessary to reverse the direction of the potential gradient applied between the outlet portion 8 and the orifice 10.

US Pat. No. 6,949,741.

WO 2004/098743.

  One problem with conventional DART is that, as shown in FIG. 3, when the sample is powder 11, the sample is scattered by the wind pressure of the excitation gas 12 when the sample is vaporized and thermally desorbed. Met. In order to avoid this problem, conventionally, a sample 11 and a binder 14 such as polyethylene glycol (PEG) are mixed using a mortar 13, and a mixture 15 is formed into a mixed molding solid 17 using a pressure molding machine 16. The sample was ionized by touching the excitation gas 12 while the sample was held with tweezers 18 or the like.

  Therefore, in the case of a powder sample, a pretreatment for kneading with a binder to form a solid is necessary. In addition, depending on the type of binder, it cannot withstand the high temperature of the excitation gas, and the solid state cannot be maintained, and analysis may not be possible. In that case, it was necessary to make a measurement by adhering to an adhesive tape that does not easily generate a background signal, or dissolving it in a solvent and applying it to the tip of a glass rod or the like.

  In view of the above-described points, an object of the present invention is to provide an atmospheric pressure ionization method and a sample holding device that do not require pretreatment for an atypical sample.

In order to achieve this object, the atmospheric pressure ionization method according to the present invention comprises:
Or wrap powder sample to a thin film excitation gas permeability, or a thin film excitation gas permeable, fibrous body, any of the porous body with or impregnated with a liquid sample excitation gas from the front of the sample to the sample against, the sample is reacted with excitation gas, it is characterized in that the ion flow generated rearward of the sample so as to detect by mass spectrometry.

  Further, the excitation gas is a gas containing excited molecules generated by corona discharge or glow discharge.

  Further, the thin film is a thin film containing fiber.

  In addition, the thin film containing the fibrous material is paper or ceramic paper.

  Further, the present invention is characterized in that the sample is soaked into a fibrous body or a porous body, an excitation gas is applied to the sample, and the sample is reacted with the excitation gas to be ionized.

Further, the sample holding device of the present invention holds the sample in a holder that can move in the vertical and horizontal directions, and applies an excitation gas to the sample from the front of the sample, thereby ionizing the sample and placing it behind the sample. It is characterized by being introduced into the ion inlet of the mass spectrometer.

The sample holder is a sample holder used in the atmospheric pressure ionization method according to claim 1,
A communication part communicating between the front side and the rear side is provided, and the sample is held in ceramic paper through which the excitation gas permeates, or in cotton, cloth, thread, gauze, towel, sponge, which can impregnate the sample, It is characterized by being held in the communication part.

  Further, the excitation gas is a gas containing excited molecules generated by corona discharge or glow discharge.

  Further, the thin film is a thin film containing fiber.

  In addition, the thin film containing the fibrous material is paper or ceramic paper.

  The fibrous body or the porous body is any one of cotton, cloth, thread, gauze, towel, and sponge.

According to the atmospheric pressure ionization method of the present invention,
Or wrap powder sample to a thin film excitation gas permeability, or a thin film excitation gas permeable, fibrous body, any of the porous body with or impregnated with a liquid sample excitation gas from the front of the sample to the sample against, the sample is reacted with excitation gas. Thus is detected by mass spectrometry the ions flow generated rearward of the sample,
It is possible to provide an atmospheric pressure ionization method that does not require pretreatment for an amorphous sample.

Moreover, according to the sample holding device of the present invention, the sample holding device used in the atmospheric pressure ionization method according to claim 1,
The sample is held in a holder that can be moved vertically and horizontally, and an excitation gas is applied to the sample from the front of the sample, thereby ionizing the sample and introducing it to the ion introduction port of the mass spectrometer placed behind the sample. I did so
It is possible to provide an atmospheric pressure ionization method that does not require pretreatment for an amorphous sample.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 4 shows an embodiment of the atmospheric pressure ionization method according to the present invention.

  First, without pre-processing the powder sample 21, a small amount is placed at the fold of the folded paper 22, and sealed. When the excitation gas 23 is sprayed on the powder sample 21 collected at the fold, the excitation gas molecules 24 pass through the gaps in the fibers of the paper 22 and directly act on the powder sample 21 to ionize the powder sample 21. To do. The generated ions further pass through the gap between the fibers of the paper 22 on the opposite side to become an ion stream 26. At this time, since paper is used for the sample holder, the temperature of the excitation gas is set to 200 ° C. or lower so that the paper does not burn.

  FIG. 5 is another embodiment of the atmospheric pressure ionization method according to the present invention. If the powder sample 21 is not ionized unless it is at a high temperature of 200 ° C. or higher, it will burn in the paper used in the previous embodiment, so the fiber of ceramic (silica or alumina as the main component), which is more heat resistant than paper, is powdered. Using a thin ceramic paper 25 woven so dense that the body sample 21 does not pass, the powder sample 21 is wrapped around the ceramic paper 25 and sprayed with the excitation gas 23 in the same manner as in the previous embodiment. Then, the molecules 24 of the excitation gas 23 are allowed to directly act on the powder sample 21 by passing through the gaps in the fibers of the ceramic paper 25 to ionize the powder sample 21, and further pass through the gaps in the fibers of the ceramic paper 25 on the opposite side. To generate an ion stream 26.

  FIG. 6 shows another embodiment of the atmospheric pressure ionization method according to the present invention. When using the gel sample 27, the gel sample 27 is wrapped around the paper 22 or the ceramic paper 25 and sprayed with the excitation gas 23 in the same manner as in the previous embodiment. Then, the molecules 24 of the excitation gas 23 are allowed to act directly on the gel sample 27 by passing through the gaps between the fibers of the paper 22 or the ceramic paper 25 to ionize the gel sample 27, and further the paper 22 or ceramic paper 25 on the opposite side. The ion stream 26 is generated by passing through the fiber gap.

  FIG. 7 shows another embodiment of the atmospheric pressure ionization method according to the present invention. When the liquid sample 28 is used, the liquid sample 28 is directly impregnated into the paper 22 or the ceramic paper 25 used in the previous embodiment, and the liquid sample 28 is ionized by the same method as the previous method, so that the paper 22 or the ceramic paper is used. An ion stream 26 is generated toward the opposite side of 25. In this example, instead of paper and ceramic paper, liquid samples are impregnated with various fibrous bodies and porous bodies such as cotton, such as absorbent cotton, and cloth, thread, gauze, towels, sponges, etc. Can be ionized.

  FIG. 8 shows an embodiment of a sample holding device according to the present invention. A sample 32 (or a sample 32 soaked in a single sample holding sheet 31) sandwiched between two folded sample holding sheets 31 made of paper or ceramic paper is pressed and fixed to the L-shaped plate 33 by a clip 34. At this time, the L-shaped plate 33 includes a communication part (notch part) that communicates the front side and the rear side, and the sample 32 is held in contact with the communication part.

  A plug 37 to be inserted into a holder 36 provided on the stage 35 is fixed to the L-shaped plate 33. A pin 38 is attached to the plug 37, and when the plug 37 is inserted into the holder 36, the pin 38 is fitted into a pin hole 39 provided in the holder 36 and is prevented from rotating.

  In a state where the plug 37 is inserted into the holder 36, the excitation gas 41 ejected from the DART nozzle 40 passes through the air-permeable sample holding sheet 31 and directly hits the sample 32, whereby the sample 32 is ionized. , Introduced into an orifice 42 placed behind the sample 32.

  The sample position suitable for ionization is selected by monitoring the quantitative change of the generated ions with a mass spectrometer while moving the stage 35 left and right or moving the holder 36 up and down. Since the sample 32 is held in contact with the communicating portion of the L-shaped plate 33, the sample 32 is introduced into the orifice 42 after being ionized without being obstructed by the L-shaped plate 33.

  In this example, the sample holding method has been described with a thin film body such as paper or ceramic paper in mind, but instead of the sample holding sheet 31 made of paper or ceramic paper, cotton such as absorbent cotton or cloth Needless to say, various fiber bodies and porous bodies such as yarns, threads, gauze, towels and sponges can be used as the sample holder. However, among these, materials that are vulnerable to heat cannot withstand use at high temperatures, and are therefore limited to ionization only at low temperatures.

  FIG. 9 shows another embodiment of the sample holding device according to the present invention. In the present embodiment, a rotation mechanism 43 is provided between the stage 35 and the holder 36 of the previous embodiment, and a function of tilting the portion of the sample 32 of the sample holding sheet 31 attached to the L-shaped plate 33 is added. Thereby, when selecting the sample position suitable for ionization, the angle at which the excitation gas 41 strikes can be adjusted.

  FIG. 10 shows another embodiment of the sample holding device according to the present invention. In this embodiment, unlike the previous embodiment, there is a method in which a sample sandwiched between two folded sample holding sheets (or a sample soaked in a single sample holding sheet) is pressed and fixed to an L-shaped plate with a clip. Instead, a glass rod 51 with a sample 52 applied to the tip is used.

  The arm 54 is integrated with a plug 53 that is inserted into a holder 57 provided on the stage 58. A clip 55 is fixed to the upper end of the arm 54 with a screw 56, and the glass rod 51 is sandwiched between the clip 55 and the arm 54 and fixed. A pin is attached to the plug 53, and when the plug 53 is inserted into the holder 57, the pin fits into a pin hole provided in the holder 57 and is prevented from rotating.

  In a state where the plug 53 is inserted into the holder 57, the excitation gas ejected from a DART nozzle (not shown) directly hits the sample 52, whereby the sample 52 is ionized and placed behind the sample 52 (not shown). Introduced into the orifice.

  A sample position suitable for ionization is selected by monitoring the quantitative change of the generated ions with a mass spectrometer while moving the stage 58 left and right or moving the holder 57 up and down. Since the sample 52 is held at the tip of the glass rod 51, the sample 52 is introduced into an orifice (not shown) without being obstructed by the glass rod 51 after ionization.

  FIG. 11 shows another embodiment of the sample holding device according to the present invention. In this embodiment, unlike the previous embodiment, a method in which a sample sandwiched between two folded sample holding sheets (or a sample soaked in a single sample holding sheet) is pressed and fixed to an L-shaped plate with a clip. Instead of using a glass rod coated with a sample at the tip, a method in which the solid sample 66 is sandwiched between the reverse action tweezers 63 is adopted.

  The arm 62 is integrated with a plug 61 that is inserted into a holder 67 provided on the stage 68. A clamp 64 for fixing the reverse action tweezers 63 is fixed to the upper end portion of the arm 62 with a screw 65, and the rear part of the reverse action tweezers 63 is inserted into the gap of the clamp 64 and fixed with the screw 65. A pin is attached to the plug 61, and when the plug 61 is inserted into the holder 67, the pin fits into a pin hole provided in the holder 67 and is prevented from rotating.

  In a state where the plug 61 is inserted into the holder 67, the excitation gas ejected from a DART nozzle (not shown) directly hits the solid sample 66 sandwiched between the counteracting tweezers 63, thereby ionizing the solid sample 66. The solid sample 66 is introduced into an orifice (not shown) placed behind the solid sample 66.

  The sample position suitable for ionization is selected by monitoring the quantitative change of the generated ions with a mass spectrometer while moving the stage 68 left and right and moving the holder 67 up and down. Since the solid sample 66 is held at the tip of the counteracting tweezers 63, the solid sample 66 is introduced into an orifice (not shown) without being disturbed by the counteracting tweezers 63 after ionization.

  It can be widely used for mass spectrometry by DART.

It is a principle figure of DART. It is a figure explaining the mechanism of ionization by DART. It is a figure which shows the problem of DART. It is one Example of the ionization method concerning this invention. It is another Example of the ionization method concerning this invention. It is another Example of the ionization method concerning this invention. It is another Example of the ionization method concerning this invention. It is one Example of the sample holding device concerning this invention. It is another Example of the sample holding device concerning this invention. It is another Example of the sample holding device concerning this invention. It is another Example of the sample holding device concerning this invention.

Explanation of symbols

1: first chamber, 2: second chamber, 3: third chamber, 4: gas introduction pipe, 5: needle electrode, 6: partition, 7: partition, 8: outlet, 9: sample, 10 : Orifice, 11: Powder sample, 12: Excitation gas, 13: Mortar, 14: Binder, 15: Mixture, 16: Pressure molding machine, 17: Mixed molding solid, 18: Tweezers, 21: Powder sample, 22 : Paper, 23: excited gas, 24: excited molecule, 25: ceramic paper, 26: ion flow, 27: gel sample, 28: liquid sample, 31: sample holding sheet, 32: sample, 33: L-shaped plate, 34: Clip, 35: Stage, 36: Holder, 37: Plug, 38: Pin, 39: Hole, 40: Nozzle, 41: Excitation gas, 42: Orifice, 43: Rotating mechanism, 51: Glass rod, 52: Sample 53: Plug, 54: Arm, 5: Clip, 56: screw, 57: Holder, 58: Stage 61: plug, 62: arm, 63: adverse Tweezers, 64: clamp, 65: screw, 66: solid sample, 67: Holder, 68: Stage

Claims (11)

Or wrap powder sample to a thin film excitation gas permeability, or a thin film excitation gas permeable, fibrous body, any of the porous body with or impregnated with a liquid sample excitation gas from the front of the sample to the sample against, the sample is reacted with the excitation gas, atmospheric pressure ionization method characterized in that the ion flow generated rearward of the sample so as to detect by mass spectrometry. 2. The atmospheric pressure ionization method according to claim 1, wherein the excited gas is a gas containing excited molecules generated by corona discharge or glow discharge. The atmospheric pressure ionization method according to claim 1, wherein the thin film is a thin film containing fibrin. 4. The atmospheric pressure ionization method according to claim 3, wherein the thin film containing fibrin is paper or ceramic paper. 3. The atmospheric pressure ionization method according to claim 1, wherein the fibrous body or the porous body is one of cotton, cloth, thread, gauze, towel, and sponge. A sample holding device used in the atmospheric pressure ionization method according to claim 1,
The sample is held in a holder that can be moved vertically and horizontally, and an excitation gas is applied to the sample from the front of the sample, thereby ionizing the sample and introducing it to the ion introduction port of the mass spectrometer placed behind the sample. A sample holding device characterized in that it is configured as described above. The holding device includes a communication portion that communicates the front side and the rear surface side, and the sample is held in a thin film through which an excitation gas passes, or in a fibrous body or a porous body that can be impregnated with the sample, and the communication portion The sample holding device according to claim 6, wherein the sample holding device is held by the holder. The atmospheric pressure ionization method according to claim 7, wherein the thin film is a thin film containing fibrin. The atmospheric pressure ionization method according to claim 7, wherein the thin film containing fiber is paper or ceramic paper. The atmospheric pressure ionization method according to claim 7, wherein the fibrous body or the porous body is any one of cotton, cloth, thread, gauze, towel, and sponge. The sample holding apparatus according to claim 6, wherein the excitation gas is a gas containing excited molecules generated by corona discharge or glow discharge.

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