JP2019007927A - Gas chromatograph mass spectrometer - Google Patents

Abstract

To reduce energy for controlling the temperature of a column in a GC-MS.SOLUTION: A column 14 provided in such a way that a heat source part 17 including a heater is made to adhere closely to the column is arranged inside a vacuum chamber 40 where a mass analysis unit 20 including an ion source 22, a quadrupole mass filter 24, etc., is arranged, and the terminal of the column 14 is connected to the ion source 22. A power supply unit 41 supplies heating electric power to the heater under control of a control unit 42, and the heater is heated, so that the column 14 is temperature-controlled. Since the heat source unit 17 is installed in the vacuum atmosphere, high heat insulation performance is obtained without using a heat insulating material. Consequently, it is possible to suppress the amount of electric power supplied to the heater and reduce analysis costs when performing the same temperature-rise analysis as in the conventional art. Furthermore, the degree of freedom of a temperature profile increases as responsiveness of temperature rise is excellent.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a gas chromatograph mass spectrometer (hereinafter appropriately abbreviated as “GC-MS”).

GC-MS generally separates various compounds contained in a sample with a gas chromatograph (GC) column, and then introduces the separated compounds into a mass spectrometer (MS). The compound is ionized and mass analyzed.
FIG. 4 is a schematic configuration diagram of a conventional general GC-MS (see Patent Document 1).

  In the gas chromatograph unit 10, a column 14 is accommodated in a column oven 15, and a sample vaporizing chamber 11 is provided at the inlet end of the column 14. A carrier gas pipe 12 is connected to the sample vaporizing chamber 11, and a carrier gas such as helium is supplied into the sample vaporizing chamber 11 through the carrier gas pipe 12 and further introduced into the column 14 through the sample vaporizing chamber 11. It has become. In the column oven 15, a heater 16 for heating the internal space and a fan (not shown) are provided.

  In the mass analyzer 20, an ion source 22, an ion lens 23, a quadrupole mass filter 24, and an ion detector 25 by an electron ionization (EI) method are disposed inside a vacuum chamber 21 that is evacuated by a vacuum pump (not shown). Etc. are arranged. Furthermore, a heating interface 30 is provided between the gas chromatograph unit 10 and the mass analyzer 20. The heating interface 30 includes a heater 32 disposed so as to surround the end 14 a of the column 14, and a heat insulating material 31 covering the outside thereof.

  In the GC-MS, a small amount of liquid sample is injected from the microsyringe 13 into the heated sample vaporizing chamber 11 while the carrier gas is supplied from the sample vaporizing chamber 11 to the column 14 at a substantially constant linear velocity. The Then, the injected liquid sample is vaporized in a short time, and the vaporized sample rides on the carrier gas and is introduced into the column 14. Actually, a split flow path (not shown) is connected to the sample vaporizing chamber 11, and a split for discharging most of the gas outside through the split flow path and introducing the remaining part of the gas into the column 14. Analysis is often done.

  The heater 16 is controlled so that the temperature in the column oven 15 is kept constant according to a predetermined temperature profile (in the case of constant temperature analysis) or is increased (in the case of temperature increase analysis). Various compounds in the sample introduced into the column 14 are temporally separated while passing through the column 14. Then, the sample gas containing the separated compound passes through the column end 14 a and is discharged to the ion source 22 of the mass spectrometer 20.

  The ion source 22 continuously ionizes the compound in the introduced sample gas. The ions derived from the compound generated here are introduced into the quadrupole mass filter 24 through the ion lens 23 and have a mass-to-charge ratio corresponding to the voltage applied to the quadrupole mass filter 24 from a power supply unit (not shown). Only ions pass through the quadrupole mass filter 24 and reach the ion detector 25. Therefore, for example, when the applied voltage to the quadrupole mass filter 24 is repeatedly scanned, the mass-to-charge ratio of ions that can reach the ion detector 25 is repeatedly scanned within a predetermined mass-to-charge ratio range. Thereby, based on the detection signal obtained by the ion detector 25, a mass spectrum in a predetermined mass-to-charge ratio range can be repeatedly acquired.

  In the GC / MS analysis as described above, the temperature in the column oven 15 may be increased up to about 300 to 450 ° C. When the sample gas that has passed through the column 14 heated to such a high temperature reaches the column end 14a and decreases in temperature, the flow of the gas is delayed and the separation performance is lowered. In order to avoid this, the column end 14 a is heated by the heater 32 in the heating interface 30 to a temperature similar to that in the column oven 15, for example. The heating interface 30 generally has a configuration in which a column end is inserted into a heater block in which a heater, a temperature sensor and the like are embedded, and the entire heater block is surrounded by a heat insulating material made of urethane or the like. Further, Patent Document 2 discloses a heating interface that uses vacuum heat insulation instead of using a heat insulating material so that maintenance can be improved and the temperature can be easily lowered when the temperature needs to be lowered.

JP-A-10-283984 JP 2001-208740 A

  In the conventional GC-MS as described above, the column oven 15 has a large internal volume and is entirely covered with a heat insulating material having a sufficient thickness, and thus has a large heat capacity. Therefore, large energy is required for heating and cooling in the column oven 15, and there is a problem that the power consumption is large and the analysis cost is high. In addition, usually, even when the heating temperature in the column oven 15 is relatively low, the heating interface 30 heats the column end 14a at a substantially constant temperature, so that there is a problem that the deterioration of the column end 14a is likely to proceed. .

  The present invention has been made to solve the above problems, and its main purpose is to reduce the heat capacity by eliminating the need for a heat insulating material for temperature control of the column, and to reduce the energy during heating. An object of the present invention is to provide a gas chromatograph mass spectrometer capable of performing the above.

The gas chromatograph mass spectrometer (GC-MS) according to the present invention made to solve the above problems is as follows.
a) a vacuum chamber to be evacuated;
b) a column of a gas chromatograph section disposed inside the vacuum chamber;
c) a heat source for heating and / or cooling the column, which is arranged inside the vacuum chamber and in close contact with the column or surrounding the column;
d) a sample introduction part for introducing a sample gas into the column;
e) an ion source that is arranged inside the vacuum chamber and into which a sample gas containing a compound separated by the column is introduced, a mass separation unit that separates ions derived from the ion source according to a mass-to-charge ratio, and An ion detector that detects the separated ions, and a mass spectrometer including:
It is characterized by having.

  In the GC-MS according to the present invention, the column of the gas chromatograph unit and the heat source unit such as a heater for heating and cooling the column are an ion source, a mass separation unit such as a quadrupole mass filter, and ion detection. It is arranged directly inside the vacuum chamber in which the parts and the like are arranged. That is, since the column is placed in a vacuum atmosphere, it is insulated from the vacuum. Therefore, a column oven that is thermally shielded from the outside by a heat insulating material is not necessary, and the heat capacity of the heating target by the heat source unit is considerably smaller than that of the conventional GC-MS.

  In the GC-MS according to the present invention, preferably, the ion source has an ionization chamber for ionizing a compound therein, and the end of the column is connected to the ionization chamber.

  In this configuration, the column end and the ionization chamber of the ion source are directly connected, and all of them are accommodated in the vacuum chamber, so that a heating interface conventionally provided between the gas chromatograph part and the mass analysis part is provided. Is no longer necessary. In addition, the entire column, including the column end, is heated or cooled in the same way, so that only the column end is not always heated by the heating interface, avoiding deterioration of the column end due to excessive heating. can do.

  In the GC-MS according to the present invention, the heat source unit can have various configurations and structures. As one embodiment, the heat source unit may include a linear, rod-shaped, or strip-shaped heater or heater block arranged so as to extend along the longitudinal direction of the column. As another embodiment, the heat source unit may include a pair of plate-like heaters or heater blocks that sandwich the column. Here, the heater block is a block made of a material having high thermal conductivity in which, for example, a heater is embedded. Further, as the heat source section for cooling the column, for example, a refrigerant pipe through which the refrigerant cooled outside the vacuum chamber flows is arranged so as to extend along the longitudinal direction of the column, or a pair of What is necessary is just to cool a plate-shaped block by such refrigerant | coolant piping. A Peltier element or the like may be used.

  In the GC-MS according to the present invention, the mass analyzer is typically a quadrupole mass analyzer, but a triple quadrupole mass analyzer or a quadrupole-time-of-flight type equipped with a collision cell. It may be a mass spectrometer (q-TOF MS).

  According to GC-MS concerning the present invention, the heat capacity can be made small by making the heat insulating material for controlling the temperature of a column substantially unnecessary. Thereby, the energy supplied when the column is heated can be reduced, and the analysis cost can be suppressed. In addition, since the heat capacity is small, it is possible to increase the rate of temperature rise, and the degree of freedom of the temperature profile during temperature rising analysis is higher than that of the conventional apparatus.

The schematic block diagram of one Example of GC-MS which concerns on this invention. The schematic sectional drawing of the column with a heater in GC-MS of a present Example. Schematic which shows another structural example of the column with a heater. The schematic block diagram of the conventional general GC-MS.

  Hereinafter, an embodiment of the GC-MS according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of a GC-MS according to the present embodiment. Constituent elements corresponding to those of the conventional GC-MS already described with reference to FIG.

  In the GC-MS of the present embodiment, a mass analyzer including an ion source 22, an ion lens 23, a quadrupole mass filter 24, and an ion detector 25 inside a vacuum chamber 40 that is evacuated by a vacuum pump (not shown). 20 is arranged, and a column 14 and a heat source unit 17 for heating the column 14 are arranged. That is, a part of the gas chromatograph unit 10 is disposed inside the vacuum chamber 40. The sample vaporizing chamber 11 is attached to the vacuum chamber 40 so that the connecting portion 11a at the inlet end of the column 14 faces the inside of the vacuum chamber 40, and the connecting portion 11a is provided with a seal for maintaining high airtightness. The inlet end of the column 14 is attached. On the other hand, the outlet end of the column 14 is directly connected to the ionization chamber of the ion source 22. Note that the inlet end and the outlet end of the column 14 may be simply connected by a joint or the like.

  As shown in FIG. 2, the heat source unit 17 is a heater block 172 that is disposed along the longitudinal direction while contacting the outer wall surface of the column 14 and in which a heater 171 is embedded. A protective housing may be provided around the heater block 172. The control unit 42 controls the power supply unit 41 according to a preset temperature profile, and accordingly, the power supply unit 41 supplies appropriate heating power to the heater 171 over time. As a result, the heater block 172 is heated and the column 14 reaches a predetermined temperature.

In the GC-MS of the present embodiment, the vacuum evacuation is performed so that the degree of vacuum inside the vacuum chamber 40 is about 10 ⁻³ to 10 ⁻⁴ Pa as in the case of the conventional GC-MS. Then, a small amount of liquid sample is injected into the sample vaporizing chamber 11 by the microsyringe 13 while the carrier gas is being supplied from the carrier gas pipe 12 to the column 14 through the sample vaporizing chamber 11. Then, the sample is vaporized in a short time, and is introduced into the column 14 on the carrier gas flow. On the other hand, as described above, the power supply unit 41 supplies heating power to the heater 171 under the control of the control unit 42, whereby the heater 171 is heated and the column 14 is heated via the heater block 172. Since the heater block 172 is disposed in a vacuum atmosphere, the heat insulating property is good. Therefore, the heat of the heater block 172 does not easily escape to the surroundings, and the column 14 can be efficiently heated even if the heating power supplied to the heater 171 is small.

  While the sample gas passes through the temperature-controlled column 14, various compounds in the sample gas are temporally separated and are directly introduced into the ionization chamber of the ion source 22 from the end of the column 14. . Since the column 14 is heated by the heater 171 and the heater block 172 to the vicinity thereof, the flow of the sample gas smoothly enters the ionization chamber without stagnation. A compound in the sample gas is ionized by, for example, an electron ionization method in the ionization chamber, and the generated ions are introduced into the quadrupole mass filter 24 through the ion lens 23. As described above, since the mass analysis unit 20 is disposed in the vacuum chamber 40 maintained in a vacuum atmosphere, the ions are separated according to the mass-to-charge ratio in the quadrupole mass filter 24, and the quadrupole mass filter. Ions passing through 24 reach the ion detector 25 and are detected.

  As described above, the GC-MS of this embodiment can perform the GC / MS analysis satisfactorily. In particular, in the GC-MS of this embodiment, no heat insulating material is used for the heat source part 17 for heating the column 14, and the heat source part 17 heats the column 14 efficiently. It can be faster than GC-MS. Therefore, the degree of freedom of the temperature profile during the temperature rising analysis is improved, and for example, the analysis can be completed in a shorter time than conventional. Further, the amount of electric power supplied to the heater 171 can be reduced to perform the same temperature rise analysis, and the analysis cost can be reduced.

  The configuration and structure of the heat source unit 17 that heats the column 14 are not limited to those shown in FIGS. 1 and 2. Another configuration example of the heat source unit 17 is shown in FIG. In this example, the column 14 is formed in a U-shaped turn many times, and the column 14 is sandwiched between a pair of flat heater blocks 172. A heater (not shown) is embedded in the heater block 172, and when the heating power is supplied to the heater, the entire heater block 172 is heated substantially uniformly. Thereby, the whole column 14 can be heated favorably. Of course, the column 14 itself may be embedded in the heater block 172.

  In addition to heating the column 14, means for cooling the column 14 may be provided in the heat source unit 17. In order to cool the column 14, for example, a refrigerant pipe through which the refrigerant cooled outside the vacuum chamber 40 may be arranged along the column 14 in the same manner as the heater 171 in FIG. 2.

  In the GC-MS of the above embodiment, the mass analysis unit 20 is a quadrupole mass analysis unit, but a triple quadrupole mass analysis unit in which a quadrupole mass filter is arranged before and after the collision cell, Of course, a quadrupole-time-of-flight mass analysis unit in which the subsequent quadrupole mass filter is replaced with a time-of-flight mass separation unit may be used.

  Moreover, the said Example and modification are only examples of this invention, and even if it changes suitably in the range of the meaning of this invention, correction, and addition, it is clear that it is included in the claim of this application.

DESCRIPTION OF SYMBOLS 10 ... Gas chromatograph part 11 ... Sample vaporization chamber 11a ... Connection part 12 ... Carrier gas piping 13 ... Micro syringe 14 ... Column 17 ... Heat source part 171 ... Heater 172 ... Heater block 20 ... Mass analysis part 22 ... Ion source 23 ... Ion lens 24 ... Quadrupole mass filter 25 ... Ion detector 40 ... Vacuum chamber 41 ... Power supply unit 42 ... Control unit

Claims (2)

a) a vacuum chamber to be evacuated;
b) a column of a gas chromatograph section disposed inside the vacuum chamber;
c) a heat source for heating and / or cooling the column, which is arranged inside the vacuum chamber and in close contact with the column or surrounding the column;
d) a sample introduction part for introducing a sample gas into the column;
e) an ion source that is arranged inside the vacuum chamber and into which a sample gas containing a compound separated by the column is introduced, a mass separation unit that separates ions derived from the ion source according to a mass-to-charge ratio, and An ion detector that detects the separated ions, and a mass spectrometer including:
A gas chromatograph mass spectrometer comprising: The gas chromatograph mass spectrometer according to claim 1,
A gas chromatograph mass spectrometer characterized in that the ion source has an ionization chamber for ionizing a compound therein, and an end of the column is connected to the ionization chamber.

Images