Mass spectrometer and mass spectroscopic method

Abstract

To prevent occurrence of unnecessary time between two cycle measurement sections temporally adjacent to each other in a mass spectrometer.SOLUTION: A plurality of measurement sections Sa1-Sa5 are set on a retention time axis on the basis of a plurality of compound peak observation periods. The starting time and the ending time of each of the measurement sections Sa1-Sa5 are corrected so as to prevent occurrence of a blank period (remainder time) r1-r5 between two measurement sections temporally adjacent to each other, and thereby the actual starting time and the actual ending time of each of the measurement sections Sb1-Sb5 are determined. Specifically, the actual starting time of the i-th cycle measurement section is adjusted to the actual ending time of the i-1-th cycle measurement section.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a mass spectrometer and a mass spectrometry method, and particularly to a technique for setting a plurality of cycle measurement intervals.

Background Art

[0002] A mass spectrometry system is composed of, for example, a gas chromatograph and a mass spectrometer (see, for example, Patent Document 1). In the gas chromatograph, a plurality of compounds are separated from a sample. In the mass spectrometer, mass spectrometry is performed on each of the separated compounds.

[0003] For example, a mass spectrometer having a first mass analyzer and a second mass analyzer has an SRM (Selected Reaction Monitoring) mode. This mode is also called the MRM (Multiple Reaction Monitoring) mode. The SRM mode is similar to the SIM (Selected Ion Monitoring) mode in terms of cyclically and sequentially selecting a plurality of mass-to-charge ratios.

[0004] In the SRM mode, for example, based on a plurality of compound peak observation periods set on the retention time axis, a plurality of cycle measurement intervals (hereinafter, sometimes simply referred to as measurement intervals) are set on the retention time axis. In each measurement interval, a measurement sequence for detecting a plurality of types of ions in a time-division manner is repeatedly executed. The repetition period of the measurement sequence is also called the cycle time (loop time). The cycle time is the time required to execute the measurement sequence once.

[0005] In a plurality of ion detection steps constituting a measurement sequence, a plurality of operating conditions corresponding to a plurality of transitions are set. A transition corresponds to a combination of the mass-to-charge ratio of a precursor ion selected by a first mass spectrometer and the mass-to-charge ratio of a product ion selected by a second mass spectrometer. Note that, even in a mode other than the SRM mode (for example, the SIM mode), a plurality of measurement intervals can be set based on a plurality of compound peak observation periods.

[0006] In each measurement interval, if the time length of the measurement interval does not match an integer multiple of the cycle time, a remaining time shorter than the cycle time will occur at the end of the measurement interval. The remaining time is a blank time during which no measurement is performed and is wasted time.

[0007] Patent Document 2 discloses a technique for adjusting a compound peak observation period (the length of a measurement event). Patent Document 3 discloses a technique for adjusting an ion detection time (event time). Patent Document 4 discloses a technique for adjusting an ion detection time (dwell time). None of Patent Documents 1 to 4 disclose a technique for preventing wasted time from occurring between two temporally adjacent measurement intervals.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0009] An object of the present invention is to prevent waste time from occurring between two cycle measurement intervals that are adjacent in time. Alternatively, an object of the present invention is to optimize the start time and end time of each cycle measurement interval.

Means for Solving the Problems

[0010] The mass spectrometer according to the present invention includes a first table for managing a plurality of compound peak observation periods set on a retention time axis, and a plurality of cycles set on the retention time axis based on the plurality of compound peak observation periods. A second table for managing measurement intervals, and a processor for determining the actual start time and actual end time of each cycle measurement interval by correcting the start time and end time of each cycle measurement interval so that a blank period does not occur between two cycle measurement intervals that are adjacent in time. It is characterized by including.

[0011] The mass spectrometry method according to the present invention includes a step of setting a plurality of cycle measurement intervals on the retention time axis based on a plurality of compound peak observation periods set on the retention time axis, and two cycle measurement intervals that are adjacent in time. A step of determining the actual start time and actual end time of each cycle measurement interval by correcting the start time and end time of each cycle measurement interval so that a blank period does not occur between them. It is characterized by including.

Effects of the Invention

[0012] According to the present invention, waste time does not occur between two cycle measurement intervals that are adjacent in time. Alternatively, according to the present invention, the start time and end time of each cycle measurement interval are optimized.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

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Figure 10

Figure 11

Mode for Carrying Out the Invention

[0014] Hereinafter, embodiments will be described with reference to the drawings.

[0015] (1) Outline of the Embodiment The mass spectrometer according to the embodiment includes a first table, a second table, and a processor. The first table is a table for managing a plurality of compound peak observation periods set on the retention time axis. The second table is a table for managing a plurality of cycle measurement intervals set on the retention time axis based on the plurality of compound peak observation periods. The processor determines the actual start time and the actual end time of each cycle measurement interval by correcting the start time and the end time of each cycle measurement interval so that no blank period occurs between two temporally adjacent cycle measurement intervals.

[0016] According to the above configuration, since no wasted time occurs between two temporally adjacent cycle measurement intervals, problems such as missing sample points and local increase in sample intervals do not occur when sampling the compound peak waveform.

[0017] The above blank period is a wasted period during which measurements are not taken despite being able to perform measurements. The time required to operate the mass spectrometer, such as the time for setting the operating conditions, is not included in the blank time. The start time and end time of each cycle measurement interval are both planned times, provisional times, or times before correction. In contrast, the actual start time and actual end time of each cycle measurement interval are both times after correction. The cycle measurement interval is a period during which a measurement sequence for detecting multiple types of ions in sequence is repeatedly executed. The cycle measurement interval can also be referred to as a loop measurement interval.

[0018] Some of all the cycle measurement intervals may be subject to correction. As long as the blank period is excluded, there may be a start time that is maintained after correction among the multiple start times, or there may be an end time that is maintained after correction among the multiple end times.

[0019] In an embodiment, the processor determines the actual start time of the i-th cycle measurement interval based on the actual end time of the (i - 1)-th cycle measurement interval while incrementing i one by one (where i is an integer of 2 or more). Further, the processor determines the actual end time of the i-th cycle measurement interval according to the actual start time of the i-th cycle measurement interval and the cycle time applied to the i-th cycle measurement interval.

[0020] By aligning the actual start time of the i-th cycle measurement interval with the actual end time of the (i - 1)-th cycle measurement interval, the blank time between the (i - 1)-th cycle measurement interval and the i-th cycle measurement interval can be excluded. Note that if no blank time occurs immediately before a certain cycle measurement interval, the start time of that cycle measurement interval may be directly determined as the actual start time.

[0021] When the pre-padding method is selected as the blank period exclusion method, the processor determines the actual end time of the i-th cycle measurement interval before the end time of the i-th cycle measurement interval (i.e., the start time of the (i + 1)-th cycle measurement interval). According to the pre-padding method, since the number of executions of the measurement sequence within the i-th cycle measurement interval is maintained, the control of the operation of the mass spectrometer becomes easy. In that case, the pre-padding amount of the (i + 1)-th cycle measurement interval is a time shorter than the cycle time applied to the i-th cycle measurement interval.

[0022] When the extension method is selected as the blank period exclusion method, the processor determines the actual end time of the i-th cycle measurement interval after the end time of the i-th cycle measurement interval (i.e., the start time of the (i + 1)-th cycle measurement interval). According to the extension method, usually, the number of executions of the measurement sequence within the i-th cycle measurement interval increases by one. In that case, the amount of backward movement of the actual start time of the (i + 1)-th cycle measurement interval (i.e., the extension amount of the i-th cycle measurement interval) is a time shorter than the cycle time applied to the i-th cycle measurement interval.

[0023] When the selection method is selected as the blank period exclusion method, the processor calculates the difference time between the predicted measurement end time within the i-th cycle measurement interval and the start time of the (i + 1)-th cycle measurement interval. Then, the processor selects a method for determining the actual end time of the i-th cycle measurement interval based on the difference time. In that case, the difference time may be compared with other times. Examples of other times include the cycle time applied to the (i + 1)-th cycle measurement interval, the extension amount in the case of adopting the above extension method, a preset threshold value, and the like. The above measurement end time is the predicted measurement end time when the measurement sequence is repeatedly executed more times without exceeding the end time of the i-th cycle measurement interval.

[0024] When the first method is selected as the above method, the processor determines the actual end time of the i-th cycle measurement interval before the end time of the i-th cycle measurement interval. That is, in that case, the pre-padding method is implemented. On the other hand, when the second method is selected as the above method, the processor determines the actual end time of the i-th cycle measurement interval after the end time of the i-th cycle measurement interval. That is, in that case, the extension method is implemented.

[0025] In an embodiment, the processor has a function of executing a correction mode and a function of executing a non-correction mode. In the correction mode, the actual start time and the actual end time of each cycle measurement interval are determined by correcting the start time and the end time of each cycle measurement interval so that no blank period occurs. In the non-correction mode, the start time and the end time of each cycle measurement interval are adopted as they are without being corrected.

[0026] According to the above configuration, the advantages of correcting the cycle measurement interval can be obtained, and the occurrence of the disadvantages caused by the correction can be prevented. The former advantage includes preventing the omission of sample points. The latter disadvantage includes a significant deviation of the actual cycle measurement interval from the planned cycle measurement interval.

[0027] In an embodiment, the processor selects a correction mode or a non-correction mode based on the cycle time applied to each cycle measurement interval. Specifically, the processor selects the correction mode when the cycle time is smaller than the threshold value, and selects the non-correction mode when the cycle time is larger than the threshold value. In an embodiment, the cycle time corresponds to the upper limit of the correction amount. When the upper limit of the correction amount is larger than the threshold value, the execution of the correction mode is restricted.

[0028] The mass spectrometer according to the embodiment further includes a first mass spectrometer, a collision cell, a second mass spectrometer, and a detector. The first mass spectrometer applies a first mass spectrometry to the ions generated from the sample. The collision cell accumulates and discharges the ions that have passed through the first mass spectrometer. The second mass spectrometer applies a second mass spectrometry to the ions discharged from the collision cell. The detector detects the ions that have passed through the second mass spectrometer. The processor controls the operations of the first mass spectrometer, the collision cell, and the second mass spectrometer according to the measurement sequence applied to each cycle measurement period. According to the accumulation time and the discharge time of the collision cell, the execution conditions of the correction mode may be determined, or the execution possibility of the correction mode may be determined.

[0029] The mass spectrometry method according to the embodiment includes a setting step and a correction step. In the setting step, a plurality of cycle measurement intervals are set on the retention time axis based on a plurality of compound peak observation intervals set on the retention time axis. In the correction step, the actual start time and the actual end time of each cycle measurement interval are determined by correcting the start time and the end time of each cycle measurement interval so that no blank period occurs between two temporally adjacent cycle measurement intervals.

[0030] A program for executing the above mass spectrometry method is installed in an information processing apparatus via a network or via a portable storage medium. The information processing apparatus has a non-temporary storage medium for storing the program. The information processing apparatus corresponds to a mass spectrometry system or a mass spectrometer, or is an information processing apparatus within the mass spectrometry system.

[0031] (2) Details of the Embodiment FIG. 1 shows a configuration example of a mass spectrometry system according to an embodiment. The illustrated mass spectrometry system 10 includes a gas chromatograph (GC) 12, a mass spectrometer 14, and an information processing device 16. The mass spectrometer 14 and the information processing device 16 constitute a mass analyzer. The mass spectrometer 14 operates according to an operation mode selected from a plurality of operation modes. The plurality of operation modes include a scan mode, a SIM mode, and an SRM mode. Hereinafter, on the premise of executing the SRM mode, the configuration and operation of the mass spectrometry system 10 will be described.

[0032] The gas chromatograph 12 has a column that separates or extracts a plurality of compounds from a sample. The separated plurality of compounds are sequentially sent to the mass spectrometer 14. A liquid chromatograph may be provided instead of the gas chromatograph 12.

[0033] The mass spectrometer 14 includes an ion source 18, a first mass analyzer 20, a collision cell 22, a second mass analyzer 24, a detector 26, and a power supply unit 28. The collision cell 22 is provided as needed. The ion source 18 is, for example, an ion source according to the electron ionization method. An ion source according to another ionization method may be provided. In the ion source 18, each compound separated from the sample is ionized.

[0034] The first mass analyzer 20 is constituted by, for example, a quadrupole mass analyzer. The first mass analyzer 20 is a mass filter that allows only ions having a selected mass-to-charge ratio (m / z) to pass through. The collision cell 22 has quadrupoles and contains a collision gas therein. Ions (precursor ions) collide with the collision gas, causing dissociation in the ions and generating product ions. The collision cell 22 according to the embodiment repeats the accumulation of ions and the discharge of the accumulated ions within an ion detection period (transition setting period). The transition corresponds to a combination of the mass-to-charge ratio of the precursor ions and the mass-to-charge ratio of the product ions.

[0035] The second mass spectrometer 24 is constituted by, for example, a quadrupole mass spectrometer. The second mass spectrometer 24 is a mass filter that allows only ions having a specified mass-to-charge ratio to pass through. The ions that have passed through the second mass spectrometer are detected by the detector 26. The detection signal output from the detector 26 is sent to the information processing device 16 via a signal processing circuit (not shown).

[0036] Power is supplied from the power supply unit 28 to the ion source 18, the first mass spectrometer 20, the collision cell 22, the second mass spectrometer 24, and the detector 26, and a voltage signal is also supplied. The information processing device 16 controls the operation of the mass spectrometer 14 through the control of the power supply unit 28.

[0037] The information processing device 16 is constituted by a computer. The information processing device 16 has a processor 30 and a memory 34. The processor 30 is constituted by a CPU that executes programs. The memory 34 is a semiconductor memory. The information processing device 16 further has an input device 36 and a display 38. The input device 36 is constituted by a keyboard, a pointing device, etc. The display 38 is constituted by a liquid crystal display, etc.

[0038] The processor 30 functions as a control unit 40 and an arithmetic unit 41. The control unit 40 has, in addition to the function of controlling the operation of the mass spectrometer 14, the function of setting a plurality of compound peak observation periods, the function of setting a plurality of measurement intervals (a plurality of cycle measurement intervals) based on the plurality of compound peak observation periods, the function of correcting the plurality of measurement intervals, etc. In FIG. 1, the function of correcting the plurality of measurement intervals is expressed as a correction unit 42.

[0039] The calculation unit 41 has a mass spectrum generation function, a chromatogram generation function, and the like. A mass spectrum, a chromatogram, and the like are displayed on the display 38. Using the input device 36, a cycle time or a target cycle time that is commonly applied over a plurality of measurement intervals is input by the user, or a cycle time or a target cycle time is input for each measurement interval. The target cycle time is a reference value when automatically setting the cycle time in consideration of various conditions.

[0040] The mass spectrometer according to the embodiment (that is, the mass spectrometer 14 and the information processing device 16) has a correction mode and a non-correction mode. When the correction mode is executed, a plurality of planned measurement intervals are corrected, and the operation of the mass spectrometer 14 is controlled according to the corrected plurality of measurement intervals. When the non-correction mode is executed, the operation of the mass spectrometer 14 is controlled according to the plurality of planned measurement intervals. Hereinafter, the configuration and operation of the information processing device 16 will be described assuming the correction mode exclusively.

[0041] The memory 34 has a compound table 44 as a first table and a measurement interval table 46 as a second table. The compound table 44 is a table for managing a plurality of compound peak observation periods. The measurement interval table 46 is a table for managing a plurality of measurement intervals (a plurality of cycle measurement intervals) set based on the plurality of compound peak observation periods.

[0042] In the correction mode, the correction unit 42 corrects the time length of each measurement interval so that it is an integer multiple of the cycle of the cycle measurement executed in the measurement interval. That is, the start time and the end time of each measurement interval are corrected so that no blank time occurs. Thereby, the actual start time and the actual end time of each measurement interval are determined.

[0043] The start time is the planned start time, that is, the start time before correction. The end time is the planned end time, that is, the end time before correction. The actual start time is the start time after correction, and the actual end time is the end time after correction. Note that in the non-correction mode, the start time and end time of each measurement interval are directly adopted. In that case, usually, there is a time difference shorter than the cycle of the cycle measurement between the end time of each measurement interval and the actual end time, which can be called the remaining time. The remaining time will be described in detail later.

[0044] Figure 2 shows an example of the compound table 44. The compound table 44 has a plurality of records 48 corresponding to a plurality of compounds separated from the sample. Each record 48 has information 50 for identifying the compound, information 52 indicating the predicted appearance time of the compound peak, information 54 indicating the start time of the compound peak observation period, information 56 indicating the end time of the compound peak observation period, information 58 indicating the mass-to-charge ratio of the precursor ion, information 60 indicating the mass-to-charge ratio of the product ion, and so on.

[0045] The combination of the mass-to-charge ratio of the precursor ion and the mass-to-charge ratio of the product ion is the transition 61. Usually, one record 48 contains a plurality of transitions 61. For example, it includes one transition corresponding to the quantitative ion and one or more transitions corresponding to the confirmation ion.

[0046] In each record 48, the predicted appearance time of the compound peak, the start time of the compound peak observation period, and the end time of the compound peak observation period are usually set in advance. They may also be set based on the user's designation.

[0047] Figure 3 shows an example of the measurement interval table 46. The measurement interval table 46 has a plurality of records 62 corresponding to a plurality of measurement intervals. The plurality of measurement intervals are automatically set based on the overlapping state of the plurality of compound peak observation periods. The plurality of measurement intervals may also be set based on the user's designation.

[0048] Each record 62 includes information 64 for identifying a measurement interval, information 66 indicating a start time, information 68 indicating an end time, information 70 indicating a corrected start time (actual start time), information 72 indicating a corrected end time (actual end time), information 74 indicating a repetition period (cycle time) of a measurement sequence, and the like. A cycle time is determined for each measurement interval, or a common cycle time is determined over a plurality of measurement intervals. The cycle time may be specified by a user or may be automatically determined.

[0049] In the correction mode, an actual start time and an actual end time are calculated and registered in the measurement interval table 46. They may be registered in other tables. In the non-correction mode, the calculation of the actual start time and the actual end time is not performed.

[0050] Using FIG. 4, the setting of a plurality of measurement intervals based on a plurality of compound peak observation periods and a plurality of remaining times occurring within the plurality of measurement intervals will be described. In FIG. 4, the horizontal axis is the retention time (RT) axis. Note that in FIG. 4, the ion flight time in the mass spectrometer, that is, the delay time, is not reflected.

[0051] The chromatogram 76 includes a plurality of compound peaks 84, 86, 88. The reference numeral 78 indicates a compound peak observation period group. The compound peak observation period group 78 is composed of three compound peak observation periods 90, 92, 94. For example, the compound peak observation period 90 is a period that spreads in the positive and negative directions centered on the predicted appearance time RT1, and the spread width in each direction is ΔRT1. Measurement conditions for measuring compound ions are associated with each of the compound peak observation periods 90, 92, 94.

[0052] More specifically, the compound peak observation period 90 is a period from the start time A1 to the end time B1, the compound peak observation period 92 is a period from the start time A2 to the end time B2, and the compound peak observation period 94 is a period from the start time A3 to the end time B3.

[0053] Based on the compound peak observation period group 78, the measurement interval group 80 is set. Specifically, based on the delimiter times C1 to C6 defined by a plurality of start times A1 to A3 and a plurality of end times B1 to B3, a measurement interval group 80 consisting of five measurement intervals from measurement interval Sa1 to measurement interval Sa5 is set. Each of the measurement intervals Sa1 to Sa5 is before correction.

[0054] The measurement interval Sa1 is the interval from start time X1 to end time Y1. X1 coincides with A1. The measurement interval Sa2 is the interval from start time X2 to end time Y2. X2 coincides with A2 and also coincides with Y1. The measurement interval Sa3 is the interval from start time X3 to end time Y3. X3 coincides with B1 and also coincides with Y2. The measurement interval Sa4 is the interval from start time X4 to end time Y4. X4 coincides with A3 and also coincides with Y3. The measurement interval Sa5 is the interval from start time X5 to end time Y5. X5 coincides with B2 and also coincides with Y4. Y5 coincides with B3.

[0055] The symbol 82 indicates five packet sequences corresponding to the five measurement intervals Sa1 to Sa5. Each packet sequence is composed of a plurality of packets 96, 98 consecutive on the hold time axis. Each packet 96, 98 corresponds to one execution of the measurement sequence. The number of packets represents the number of executions of the measurement sequence. The width of each packet 96, 98 represents the cycle time. Each individual measurement sequence consists of a plurality of ion detection operations for detecting a plurality of types of ions. Each ion detection operation includes one or more ion accumulation and ejection operations in the collision cell.

[0056] The packet 98 represents one measurement sequence executed within the measurement interval Sa2. Specifically, the packet 98 consists of a portion 100 corresponding to a plurality of ion detection operations for observing the compound peak 84 and a portion 102 corresponding to a plurality of ion detection operations for observing the compound peak 86.

[0057] Since the measurement interval group 80 is defined based on the compound peak observation period group 78, the time lengths of the individual measurement intervals Sa1 to Sa5 usually do not become an integer multiple of the cycle time applied to the measurement interval. When the time length of each measurement interval is divided by the cycle time applied to each measurement interval, a quotient Q and a remainder R are generated. The quotient Q corresponds to the number of executions of the measurement sequence. The remainder R corresponds to the remaining time. At the end of each of the individual measurement intervals Sa1 to Sa5, remaining times r1 to r5 shorter than the cycle time are inevitably generated. The remaining times r1 to r5 are times when ion measurement is not being performed and are blank periods.

[0058] Reference numeral 104 indicates the plot timing. A plurality of detection values corresponding to a plurality of types of ions obtained by one execution of the measurement sequence are plotted on the chromatograph coordinate system. Usually, the plurality of detection values obtained by one execution of the measurement sequence are plotted on the same coordinates (reference time) in the horizontal direction. When the remaining times r1 to r5 occur, the plot interval temporarily expands under the influence, and thus the quality of the compound peak waveform deteriorates.

[0059] FIG. 5 shows a correction method according to an embodiment. The correction method according to the embodiment is a correction method following the pre-filling method. Note that the measurement interval group 80 and the five packet sequences 82 are the same as those shown in FIG. 4.

[0060] Reference numeral 110 indicates the five packet sequences after correction. Reference numeral 112 indicates the measurement interval group after correction.

[0061] The actual start time Xb1 of the first measurement interval Sb1 is the same as the start time Xa1 before correction. The actual end time Yb1 of the first measurement interval Sb2 is determined by dividing the time length from the actual start time Xb1 of the first measurement interval Sb1 to the end time (end time before correction) Ya1 of the first measurement interval Sb1 by the cycle time applied to the first measurement interval Sb1. Specifically, the actual end time Yb1 is determined by multiplying the quotient obtained by the division by the cycle time. Alternatively, it is determined by subtracting the remainder from the end time Ya1 before correction.

[0062] Note that although the end time of the first measurement interval is corrected, the start time of the first measurement interval is maintained. Focusing on this point, it may be understood that special processing or exceptional processing is applied only to the first measurement interval. Under such an understanding, each subsequent measurement interval from the second one is the original object to be corrected.

[0063] The actual start time and actual end time of each subsequent measurement interval from the second one are calculated as follows. Hereinafter, i is an integer of 2 or more.

[0064] The actual start time of the i-th measurement interval is set to the same time as the actual end time of the (i - 1)-th measurement interval. This eliminates the remaining time. The actual end time of the i-th measurement interval is determined by dividing the time length from the actual start time of the i-th measurement interval to the end time (end time before correction) of the i-th measurement interval by the cycle time applied to the i-th measurement interval. Specifically, it is determined by multiplying the quotient obtained by the division by the cycle time. Alternatively, it is determined by subtracting the remainder obtained by the division from the end time of the i-th measurement interval.

[0065] By repeating the above calculations while incrementing i one by one, the start times Xa2 to Xa5 and end times Ya2 to Ya5 are corrected in order from the second measurement interval to the last measurement interval. That is, the actual start times Xb2 to Xb5 and actual end times Yb2 to Yb5 are determined in order from the second measurement interval to the last measurement interval (see reference numeral 123).

[0066] In FIG. 5, the packets 116, 118, and 120 shown in gray are, as a result of the above correction, the added packets. In the illustrated example, three measurement sequences will be added.

[0067] According to the above correction, excess time is eliminated, and at the same time, the measurement time can be increased. The reference numeral 122 indicates the plotting timing of a plurality of detection values. According to the above correction, it is possible to prevent a problem in which the plot interval locally increases due to the influence of excess time. That is, the quality of the displayed compound peak waveform can be improved.

[0068] FIG. 6 shows an operation example according to an embodiment. The content shows the functions of the correction unit shown in FIG. 1. S8 is a correction step, and S22 is a sample measurement step.

[0069] In S10, the count value k is initialized, that is, 1 is assigned to k. k is an integer of 1 or more. In S12, it is determined whether k is greater than 1. When k = 1, S16 is executed. For example, for the first measurement interval, in S16, the start time before correction is regarded as the actual start time, and the actual end time is specified based on the actual start time and the cycle time.

[0070] For the second and subsequent measurement intervals, S14 is executed. In S14, the actual start time of the k-th measurement interval is specified based on the actual end time of the (k - 1)-th measurement interval. Specifically, the actual start time of the k-th measurement interval is aligned with the actual end time of the (k - 1)-th measurement interval. Then, in S16, for the k-th measurement interval, the actual end time is specified based on the actual start time and the cycle time.

[0071] In S18, the actual start time and the actual end time are registered in the measurement interval table. In S20, it is determined whether k has reached the maximum value kmax of the measurement interval numbers. If k has not reached the maximum value kmax, in S21, after k is incremented by one, each step after S12 is executed again. If k has reached the maximum value kmax, in S22, the measurement of the sample is executed. Note that the maximum value kmax is stored in the memory 34.

[0072] In FIG. 7, the compound peak 144 according to the comparative example is shown. The horizontal axis is the retention time axis, and the vertical axis is the intensity axis. Each point 146 represents a detected value. There is an extra time 148 between a certain measurement interval 140 and the next measurement interval 142. The reference numeral 150 indicates the plot interval within the measurement interval 140. The plot interval is the same as the plot interval in the next measurement interval 142. Affected by the extra time 148, a large plot interval 152 has occurred within the compound peak 144. The plot interval 152 is larger than the plot interval 150. At the position where the large plot interval 152 has occurred, the smoothness of the waveform has decreased (see reference numeral 145).

[0073] In FIG. 8, the compound peak 144A according to the embodiment is shown. The horizontal axis is the retention time axis, and the vertical axis is the intensity axis. By excluding the extra time, the plot interval 152A at the transition part between the two measurement intervals is the same as the plot interval 150. The entire compound peak 144A has become smooth.

[0074] As shown in FIG. 9, in the mass spectrometer according to the embodiment, the correction mode and the non-correction mode are selected according to the situation. Specifically, when a common cycle time is determined over a plurality of measurement intervals, the correction mode or the non-correction mode is selected based on the common cycle time.

[0075] In S30, the common cycle time Ct is compared with a threshold value Ct1. If the common cycle time Ct is smaller than the threshold value Ct1, a correction mode is executed in S32. In the correction mode, as already described, the start time and the end time of each measurement interval are corrected. On the other hand, if the common cycle time Ct is larger than the threshold value Ct1, a non-correction mode is executed in S34. In the non-correction mode, the start time and the end time of each measurement interval are adopted as they are.

[0076] When the common cycle time is large, if the extra time is uniformly excluded, there will be a problem that the correction amount becomes large and the corrected measurement interval group will be greatly different from the planned measurement interval group. As shown in FIG. 9, if the correction mode or the non-correction mode is selected according to the magnitude of the common cycle time, it is possible to exclude the extra time as long as the above problem does not occur.

[0077] For each measurement interval, the correction mode or the non-correction mode may be selected according to the magnitude of the cycle time applied to the measurement interval. The correction mode or the non-correction mode may be selected according to other criteria.

[0078] Next, a modification example will be described. FIG. 10 shows an extension method as a first modification example. FIG. 11 shows a selection method as a second modification example. In FIGS. 10 and 11, the same elements as those shown in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted.

[0079] In FIG. 10, the measurement interval group 80 before correction and the five packet sequences 82 before correction are the same as those shown in FIG. 4. The reference numeral 124 indicates the five packet sequences after correction. The reference numeral 126 indicates the measurement interval group after correction.

[0080] First, the first measurement interval Sa1 is the object to be processed. The start time Xa1 before correction is defined as the actual start time Xb1. By dividing the time length from the actual start time Xb1 to the end time Ya1 before correction by the cycle time applied to the first measurement interval Sa1, the quotient P is obtained. By adding 1 to P and multiplying the result (P + 1) by the cycle time, the actual end time Yb1 is specified. The actual end time Yb1 is the time that is later than the end time Ya1 before correction by the extension amount.

[0081] For the second and subsequent measurement intervals, the following processing is performed. i is an integer of 2 or more.

[0082] The actual start time of the i-th measurement interval is made the same as the actual end time of the (i - 1)-th measurement interval (see reference numeral 128). This eliminates the remaining time. Next, by dividing the time length from the actual start time of the i-th measurement interval to the end time of the i-th measurement interval by the cycle time applied to the i-th measurement interval, the quotient P is specified. By multiplying (P + 1) by the cycle time, the actual measurement time is calculated. The actual end time is specified as the point in time when the actual measurement time has elapsed from the actual start time.

[0083] By repeating the above calculations while incrementing i one by one, the start times Xa2 to Xa5 and end times Ya2 to Ya5 are corrected in order from the second measurement interval to the last measurement interval. That is, the actual start times Xb2 to Xb5 and actual end times Yb2 to Yb5 of each measurement interval are specified in order from the second measurement interval to the last measurement interval (see reference numeral 129). The plurality of packets represented in gray each indicate a packet (measurement sequence) added under the extension method.

[0084] In the second modification example shown in FIG. 11, reference numeral 80A indicates a group of measurement intervals before correction. The group of measurement intervals 80A before correction has a plurality of measurement intervals Sa1 to Sa3 arranged on the holding time axis. Reference numeral 82A indicates a plurality of packet sequences before correction. Reference numeral 130 indicates a plurality of packet sequences after correction. Reference numeral 132 indicates a group of measurement intervals after correction.

[0085] In the second modification example, for each measurement interval, a pre-padding method or an extension method is selectively applied. Specifically, in the first measurement interval Sa1, the time length from the start time Xa1 (= actual start time Xb1) to the end time Ya1 is divided by the cycle time applied to the first measurement interval Sa1. Thereby, the quotient Q is specified. By multiplying the quotient Q by the cycle time, the actual measurement time is specified. The time point when the actual measurement time has elapsed from the start time Xa1 is the predicted measurement end time. The difference between the predicted measurement end time and the end time Ya1 is specified as the remaining time r1.

[0086] In the illustrated example, the remaining time r1 generated at the end of the first measurement interval Sa1 is compared with the time (usually the cycle time) t1 from the start time Xa2 of the second measurement interval Sa2 to the first reference time. When r1 < t1, the pre-padding method is selected, and when r1 > t1, the extension method is selected. In the illustrated example, the pre-padding method is selected between the first measurement interval Sb1 and the second measurement interval Sb2 (see reference numeral 134).

[0087] For the second measurement interval Sa2 as well, in the same manner as above, the remaining time r2 is calculated. The remaining time r2 is compared with the time t2 from the start time Xa2 of the third measurement interval Sa3 to the first reference time. When r2 < t2, the pre-padding method is selected, and when r2 > t2, the extension method is selected. In the illustrated example, the extension method is selected between the second measurement interval Sa2 and the third measurement interval Sa3 (see reference numeral 136). The gray packets indicate the added packets. The same process is sequentially applied to other measurement intervals.

[0088] As the reference time to be compared with the remaining times r1 and r2, time information other than the above may be adopted. For example, by multiplying the cycle time by Q + 1, another measurement end time may be predicted, and the difference u1 between that other measurement end time and the end time of the measurement period may be used as the reference time. In that case, if r1 < u1, the pre-packing method is selected, and if r1 > u1, the extension method is selected. The difference u1 corresponds to the extension amount. That is, it is a comparison between the pre-packing amount and the extension amount.

[0089] As described above, also in the second modification example, from the second measurement section to the last measurement section, in order, the start time and end time of each measurement section are corrected. That is, from the second measurement section to the last measurement section, in order, the actual start time and actual end time of each measurement section are determined (refer to reference numeral 139).

[0090] According to the correction method described above, wasted time does not occur between two temporally adjacent cycle measurement sections. Also, the start time and end time of each cycle measurement section are optimized. When the pre-packing method is adopted as the correction method, the calculation amount can be reduced and the control becomes simple.

[0091] In the above embodiment, a mass spectrometer including a first mass spectrometer that selects precursor ions and a second mass spectrometer that selects product ions generated from the precursor ions was used, but a mass spectrometer having only a single mass spectrometer may be used. When performing qualitative analysis or quantitative analysis of a plurality of compounds generated from a sample using such a mass spectrometer, the start time and end time of each cycle measurement section may be corrected so that a blank period does not occur between two temporally adjacent cycle measurement sections. In that case, the cycle measurement is performed according to the SIM mode.

Explanation of reference numerals

[0092] 10 Mass spectrometry system, 12 gas chromatograph, 14 mass spectrometer, 16 information processing device, 30 processor, 40 control unit, 42 correction unit, 44 compound table, 46 measurement interval table.

Claims

1. A first table for managing a plurality of compound peak observation periods set on a retention time axis, a second table for managing a plurality of cycle measurement periods set on the retention time axis based on the plurality of compound peak observation periods, a processor that determines the actual start time and actual end time of each cycle measurement period by correcting the start time and end time of each cycle measurement period so that no blank period occurs between two adjacent cycle measurement periods in time, A mass spectrometer characterized by including.

2. In the mass spectrometer according to Claim 1, the processor, while incrementing i one by one (where i is an integer of 2 or more), determines the actual start time of the i-th cycle measurement period based on the actual end time of the (i - 1)-th cycle measurement period, and determines the actual end time of the i-th cycle measurement period according to the actual start time of the i-th cycle measurement period and the cycle time applied to the i-th cycle measurement period, A mass spectrometer characterized by this.

3. In the mass spectrometer according to Claim 2, the processor, determines the actual end time of the i-th cycle measurement period earlier than the end time of the i-th cycle measurement period, A mass spectrometer characterized by this.

4. In the mass spectrometer according to Claim 2, the processor, determines the actual end time of the i-th cycle measurement period later than the end time of the i-th cycle measurement period, A mass spectrometer characterized by this.

5. In the mass spectrometer according to Claim 2, the processor, calculates the difference time between the predicted measurement end time within the i-th cycle measurement period and the start time of the (i + 1)-th cycle measurement period, and selects a method for determining the actual end time of the i-th cycle measurement period based on the difference time, A mass spectrometer characterized by this.

6. In the mass spectrometer according to Claim 5, the processor, when the first method is selected as the method, determines the actual end time of the i-th cycle measurement period earlier than the end time of the i-th cycle measurement period, when the second method is selected as the method, determines the actual end time of the i-th cycle measurement period later than the end time of the i-th cycle measurement period, A mass spectrometer characterized by this.

7. In the mass spectrometer according to Claim 1, The processor has a function of executing a correction mode and a function of executing a non-correction mode, in the correction mode, by correcting the start time and the end time of each cycle measurement period so that the blank period does not occur, the actual start time and the actual end time of each cycle measurement period are determined, in the non-correction mode, the start time and the end time of each cycle measurement period are adopted as they are without being corrected, A mass spectrometer characterized by the above.

8. In the mass spectrometer according to claim 7, the processor selects the correction mode or the non-correction mode based on the cycle time applied to each cycle measurement period, A mass spectrometer characterized by the above.

9. In the mass spectrometer according to claim 8, the processor, selects the correction mode when the cycle time is less than a threshold value, selects the non-correction mode when the cycle time is greater than the threshold value, A mass spectrometer characterized by the above.

10. In the mass spectrometer according to any one of claims 1 to 9, a first mass spectrometer that applies first mass spectrometry to ions generated from a sample, a collision cell that accumulates and discharges the ions that have passed through the first mass spectrometer, a second mass spectrometer that applies second mass spectrometry to the ions discharged from the collision cell, a detector that detects the ions that have passed through the second mass spectrometer, including, the processor controls the operations of the first mass spectrometer, the collision cell, and the second mass spectrometer according to a measurement sequence applied to each cycle measurement period, A mass spectrometer characterized by the above.

11. A step of setting a plurality of cycle measurement periods on the retention time axis based on a plurality of compound peak observation periods set on the retention time axis, a step of determining the actual start time and the actual end time of each cycle measurement period by correcting the start time and the end time of each cycle measurement period so that a blank period does not occur between two temporally adjacent cycle measurement periods, A mass spectrometry method characterized by including the above.

12. A program executed in an information processing apparatus, a function of setting a plurality of cycle measurement periods on the retention time axis based on a plurality of compound peak observation periods set on the retention time axis, A function that determines the actual start time and actual end time of each cycle measurement interval by correcting the start time and end time of each cycle measurement interval so that no blank period occurs between two temporally adjacent cycle measurement intervals; A program characterized by including the above.

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