JP2003016992A - Liquid chromatograph mass spectrometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve accuracy of analysis and reproducibility of analysis by keeping the temperature distribution of an analysis part in an optimized state. SOLUTION: Gas regulated in temperature by a temperature regulating part 27 is led into an ion trap chamber 2 from a collision gas leading pipe 25 or a purified gas leading pipe 26. The temperature is regulated by detecting the temperature of the ion trap chamber 2 and an analysis chamber 3 by temperature sensor S1-S4 and operating the temperature regulating part 27 by a signal from a CPU 42 on the basis of the detected values to regulate the temperature of gas to a prescribed temperature. The temperature regulated gas enters also the analysis chamber 3 from the ion trap chamber 2 and keeps the inside of the analysis chamber 3 also to the prescribed temperature. The thermal expansion of the analysis chamber 3 is thereby suppressed.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid chromatography mass spectrometer (hereinafter referred to as LC / MS), and more particularly, to an ion trap and a trap for confining ions by an electric field. The present invention relates to a liquid chromatograph / mass spectrometer that analyzes the separated ions based on differences in flight time. 2. Description of the Related Art In LC / MS, a sample liquid eluted by being separated from a column of a liquid chromatograph (LC) over time is ionized to be ionized and introduced into a mass spectrometer (MS). A trap is used. The ion trap is
One annular ring electrode having an inner surface having a rotating one-lobe hyperboloid shape, and a pair of end cap electrodes provided to face each other so as to sandwich the ring electrode and having an inner surface having a rotating two-leaf hyperboloid shape. It is comprised including. A thermoelectron generator is disposed outside the opening provided in the upper first end cap electrode, and electrons emitted from the thermoelectron generator are introduced into the ion trap through the opening, It comes into contact with the sample molecule and is ionized. On the other hand, a detector is provided outside the opening provided in the lower second end cap electrode, and detects ions emitted from the inside of the ion trap through the opening. Here, as a detector, a time-of-flight detector that detects a difference in the time of flight of an ionized sample is known. [0003] The conventional LC / MS is configured as described above. However, in a time-of-flight type detector, the flight distance of ions due to expansion of the flight tube due to a temperature change or the like. Changes, the flight time of the ions changes, affecting the reproducibility and accuracy of the analysis results. Therefore, it is desired to keep the temperature of the detector constant and suppress the thermal expansion of the flight tube. However, since the inside of the MS is in a vacuum state, it is difficult to conduct heat from the outside to the inside of the MS in a short time. On the other hand, a gas is introduced into the MS into the ion trap portion for collisional dissociation of ions and purification of ions. Therefore, the present invention aims to improve the analysis accuracy by controlling the temperature of this gas that can be introduced into the MS and directly introducing heat into the apparatus, thereby optimizing the temperature distribution of the detector. The purpose is to: [0004] In order to solve the above-mentioned problems, the present invention provides a liquid chromatograph section, an ionization section for ionizing a liquid sample supplied from the liquid chromatograph section, and the ionized sample. A liquid chromatograph / mass spectrometer comprising: an ion trap section for trapping gas; and an analysis section for analyzing trapped ions at different times of flight. And a detecting means for detecting at least the temperature of the analysis section, and adjusting the temperature of the gas to be introduced based on the detected value of the temperature detecting means. According to the present invention, the temperature of the gas to be introduced into the ion trap section is controlled by the above configuration, and heat is directly introduced into the apparatus, so that the temperature distribution in the analysis section is optimized. An LC / MS according to the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a main part of the LC / MS of the present invention. The apparatus includes an ionization chamber 1, an ion trap chamber 2, an analysis chamber 3, and a first intermediate chamber 4 separated by a partition between the ionization chamber 1 and the ion trap chamber 2.
And a second intermediate chamber 5. The ionization chamber 1 is provided with a nozzle 6 connected to a column outlet end of a liquid chromatograph (not shown). A first ion lens 7 and a second ion lens 8 are provided in the first and second intermediate chambers 4 and 5, respectively. A skimmer having a small-diameter passage hole (orifice) between the first intermediate chamber 4 and the second intermediate chamber 5 through a small-diameter desolvation pipe 9 between the ionization chamber 1 and the first intermediate chamber 4. It communicates only via 10. The desolvation pipe 9 has an inlet opening obliquely oblique to the direction in which the droplets are ejected from the nozzle 6, and the pipe has a bent shape, whereby relatively large droplets and neutral molecules are removed. Jumping into the solvent pipe 9 can be suppressed. The desolvation tube 9
Is applied with a DC voltage from a DC voltage source (not shown).
The skimmer 10 is set to the ground potential. The first ion lens 7 separates a plurality of disk-shaped metal plates along the ion optical axis by a predetermined distance, and approaches the ion optical axis in the ion traveling direction (right direction in the drawing). , A virtual rod is formed, and a plurality of virtual rods are arranged around the optical axis. A voltage in which a DC voltage and a high-frequency voltage are superimposed is applied from a DC power supply and a high-frequency voltage source (not shown) to the plate-like electrodes at each stage (three stages in the figure) of the first ion lens 7. Further, the second ion lens 8 has a configuration in which eight rod electrodes are inscribed in a predetermined circle so as to surround the ion optical axis. Of the eight rod electrodes, the rod electrodes are divided into two groups of four, one in the circumferential direction of the ion optical axis, and four rod electrodes in one group and four rod electrodes in the other group. To which a high-frequency voltage whose phase is inverted is superimposed on a DC voltage. The ions converged and accelerated by the second ion lens 8 enter the ion trap chamber 2 after being further converged by the lens electrode 11. The ion trap chamber 2 has a single annular ring electrode 21 having an inner surface having a rotating one-leaf hyperboloidal shape, and an inner surface provided opposite to sandwich the electrode and having a rotating two-leaf hyperboloidal shape. A pair of end cap electrodes 23 and 24 having
It is comprised including. When an appropriate voltage is applied to the ring electrode 21 and the end cap electrodes 23 and 24 by an RF voltage generator and an auxiliary AC voltage generator (not shown), an electric field is formed in a space surrounded by these electrodes.
The ions generated in the space can be confined. In addition, a collision gas introduction pipe for introducing a gas into the ion trap 2 after sorting the ions and colliding parent ions with the gas molecules to release daughter ions into the ion trap chamber 2. 25 and a purification gas introduction pipe 26 for purifying the inside of the ion trap chamber 2 are provided. The collision gas introduction pipe 25 is connected to a gas source 33, and the purification gas introduction pipe 26 is connected to a gas source. The gas source 33 is, for example, a He gas source, and the gas source 34 is an Ar or Xe gas source. A temperature control section 27 is provided between the gas sources 33, 34 and the introduction pipes 25, 26, and the temperature of each gas is controlled by the temperature control section 27 to a predetermined temperature. The temperature control unit 27 is configured to heat and cool the introduction pipes 25 and 26 with a Peltier element or the like. The analysis room 3 is a time-of-flight type detector in which a detection element 32 is arranged in a flight tube 31. Also,
S1 to S4 are temperature sensors, and the temperature sensors S1 to S4
Enters the detection circuit 41, and the temperatures of the ion trap chamber 2 and the analysis chamber 3 are calculated. The signal detected by the detection circuit 41 enters the CPU 42, and when the temperature is different from the temperatures of the ion trap chamber 2 and the analysis chamber 3 set by the CPU 42, a signal is sent to the temperature control unit 27 to reach a predetermined temperature. Thus, the temperature of the gas introduced into the ion trap chamber 2 is adjusted. Next, the operation of the LC / MS of this embodiment will be described. First, the voltages applied to the desolvation tube 9, the first ion lens 7, the second ion lens 8, and the ion trap chamber 2 are adjusted. Of the ions generated from the droplets sprayed from the nozzle 6, ions having a target mass number pass through the desolvation pipe 9 and are introduced into the first ion lens 7. The ions introduced into the first ion lens 7 pass through the orifice of the skimmer 10 and are introduced into the second ion lens 8.
The ions introduced into the second ion lens 8 converge with higher efficiency and enter the ion trap chamber 2. In the ion trap chamber 2, by applying an appropriate voltage to the ring electrode 21 and the end cap electrodes 23 and 24, ions can be confined in the space. And
When an auxiliary AC voltage of opposite phase is applied to the two end cap electrodes 23 and 24, ions having a mass number corresponding to the frequency of the AC voltage resonate and vibrate, and the vibrated ions are removed from the ion trap chamber 2. Is done. After the selection of ions, a gas is introduced from the collision gas introduction pipe 25, and the parent ions are cleaved by collision with the gas molecules to generate daughter ions. The signals from the temperature sensors S1 to S4 during the analysis are sent from the detection circuit 41 to the CPU 42.
to go into. The CPU calculates the temperature of the ion trap chamber 2 by averaging the signals of the temperature sensors S1 and S2, and calculates the temperature of the analysis chamber 3 by averaging the signals of the temperature sensors S3 and S4. The CPU 42 compares the temperature of the ion trap chamber 2 and the temperature of the analysis chamber 3 set in advance,
A signal is sent to the temperature control section 27 to adjust the temperature of the gas introduced into the ion trap chamber 2 so as to reach a predetermined temperature. The gas whose temperature has been adjusted also enters the analysis chamber 3, and the inside of the analysis chamber 3 is also maintained at a predetermined temperature. Thereby, thermal expansion of the analysis chamber 3 is suppressed. The generated daughter ions are two end cap electrodes 2
The voltage applied to 3, 24 is adjusted and released to the analysis chamber 3 at a time. In the analysis room 3, ions are detected due to the difference in flight time. After the ions are released from the ion trap chamber 2, the gas to be introduced is switched, and the purified gas introduction pipe 2 is switched.
Purification gas (for example, Ar) is introduced from 6. The inside of the ion trap chamber 2 is replaced by the purified gas, and the inside of the chamber becomes an inert atmosphere. Since the temperature of this gas is also controlled in the same manner as described above, the analysis chamber 3 is always kept at a constant temperature. According to the present invention, the temperature of the analysis chamber is always kept constant by the gas introduced into the ion trap chamber 2 whose temperature is controlled, and the expansion of the analysis chamber can be suppressed. Therefore, the flight distance of the ions does not change, and the accuracy and reproducibility of the analysis result are improved.

[Brief description of the drawings] FIG. 1 is a schematic diagram of an LC / MS according to the present invention. [Explanation of symbols] 1: Ionization room 2: Ion trap room 3: Analysis room 25: Impact gas introduction pipe 26: Purified gas introduction pipe 27: Temperature control unit

Claims (1)

Claims: 1. A liquid chromatograph unit, an ionization unit for ionizing a liquid sample provided from the liquid chromatograph unit, an ion trap unit for confining the ionized sample, and an ion trap unit for confining the ionized sample. In a liquid chromatograph / mass spectrometer equipped with an analysis unit for performing analysis according to a difference in time of flight, a unit for introducing a gas into the ion trap unit, a unit for controlling the temperature of the introduced gas, and at least a temperature of the analysis unit. A liquid chromatograph mass spectrometer, wherein a detecting means for detecting the temperature is provided, and the temperature of the gas to be introduced is adjusted according to the detected value of the temperature detecting means.