Quality analysis apparatus and quality analysis 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 relates 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-sharing 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 the multiple ion detection steps that constitute the measurement sequence, multiple operating conditions corresponding to multiple transitions are set. A transition corresponds to a combination of the mass-to-charge ratio of the precursor ion selected by the first mass spectrometer and the mass-to-charge ratio of the product ion selected by the second mass spectrometer. In modes other than SRM mode (e.g., SIM mode), multiple measurement intervals may be set based on the observation periods of multiple compound peaks.

[0006] If the duration of each measurement interval does not coincide with an integer multiple of the cycle time, a remainder shorter than the cycle time will occur at the end of the measurement interval. This remainder is a blank time during which no measurement is performed and is therefore wasted time.

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

[0008] [Patent Document 1] Japanese Patent Publication No. 2019-211301 [Patent Document 2] Japanese Patent Publication No. 2012-132799 [Patent Document 3] International Publication No. 2016 / 002046 [Patent Document 4] U.S. Patent No. 10892152 [Overview of the project] [Problems that the invention aims to solve]

[0009] The objective of this invention is to prevent wasted time between two temporally adjacent cycle measurement intervals. Alternatively, the objective of this invention is to optimize the start and end times of each cycle measurement interval. [Means for solving the problem]

[0010] The mass spectrometer according to the present invention includes: a first table for managing a plurality of compound peak observation periods set on the retention time axis; a second table for managing a plurality of cycle measurement intervals set on the retention time axis based on the plurality of compound peak observation periods; and a processor 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 time-adjacent cycle measurement intervals. Each cycle measurement interval is a period during which a measurement sequence for detecting multiple types of ions in time-division multiplexing is repeatedly executed, and the processor determines the actual start time of the i-th cycle measurement interval based on the actual end time of the i-1th cycle measurement interval, while increasing i by one (where i is an integer of 2 or more), and 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, which is the repetition period of the measurement sequence applied to the i-th cycle measurement interval. It is characterized by the following:

[0011] The mass spectrometry method according to the present invention includes the steps of setting a plurality of cycle measurement intervals on a retention time axis based on a plurality of compound peak observation periods set on the retention time axis, and 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 no blank period occurs between two temporally adjacent cycle measurement intervals. Each cycle measurement interval is a period during which a measurement sequence for detecting multiple types of ions in time-division is repeatedly executed. In the process of determining the actual start and end times of each cycle measurement interval, the actual start time of the i-th cycle measurement interval is determined based on the actual end time of the i-1th cycle measurement interval, while increasing i by one each time (where i is an integer of 2 or more). The actual end time of the i-th cycle measurement interval is determined according to the actual start time of the i-th cycle measurement interval and the cycle time, which is the repetition period of the measurement sequence applied to the i-th cycle measurement interval. It is characterized by the following: [Effects of the Invention]

[0012] According to the present invention, no wasted time occurs between two temporally adjacent cycle measurement intervals. Alternatively, according to the present invention, the start and end times of each cycle measurement interval are optimized. [Brief explanation of the drawing]

[0013] [Figure 1] This is a block diagram showing an example configuration of a mass spectrometry system according to an embodiment. [Figure 2] This figure shows an example of a compound table. [Figure 3] It is a diagram showing an example of a measurement interval table. [Figure 4] It is a diagram showing the remaining time that occurs at the end of each measurement interval. [Figure 5] It is a diagram showing a correction method according to an embodiment. [Figure 6] It is a flowchart showing an operation example according to an embodiment. [Figure 7] It is a diagram showing a waveform according to a comparative example. [Figure 8] It is a diagram showing a waveform according to an embodiment. [Figure 9] It is a flowchart showing the selection of a correction mode and a non-correction mode. [Figure 10] It is a flowchart showing a first modification example. [Figure 11] It is a flowchart showing a second modification example.

Mode for Carrying Out the Invention

[0014] Hereinafter, embodiments will be described based on the drawings.

[0015] (1) Outline of 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 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.

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

[0017] The blank period described above is a wasted period during which measurements are not taken despite the possibility of doing so. Time required to operate the mass spectrometer, such as time to set operating conditions, is not included in the blank period. The start and end times of each cycle measurement interval are the planned time, provisional time, or uncorrected time. In contrast, the actual start and end times of each cycle measurement interval are the corrected time. A cycle measurement interval is a period during which a measurement sequence for detecting multiple types of ions in sequence is repeatedly executed. A cycle measurement interval can also be called a loop measurement interval.

[0018] A portion of all cycle measurement intervals may be subject to correction. Insofar as blank periods are excluded, some start times may be maintained after correction among multiple start times, and some end times may be maintained after correction among multiple end times.

[0019] In one embodiment, the processor determines the actual start time of the i-th cycle measurement interval based on the actual end time of the i-1th cycle measurement interval, while incrementing i by one (where i is an integer of 2 or greater). The processor also 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-th cycle measurement interval, the blank time between the i-th cycle measurement interval and the i-th cycle measurement interval can be eliminated. If no blank time occurs immediately before a certain cycle measurement interval, the start time of that cycle measurement interval may be used as the actual start time.

[0021] If the pre-filling method is selected as the blank period exclusion method, the processor sets the actual end time of the i-th cycle measurement interval to be earlier than the end time of the i-th cycle measurement interval (i.e., the start time of the (i+1)th cycle measurement interval). With the pre-filling method, the number of executions of the measurement sequence within the i-th cycle measurement interval is maintained, making it easier to control the operation of the mass spectrometer. In this case, the amount of pre-filling for the (i+1)th cycle measurement interval is shorter than the cycle time applied to the i-th cycle measurement interval.

[0022] If the extension method is selected as the blank period exclusion method, the processor sets the actual end time of the i-th cycle measurement interval to be later than the end time of the i-th cycle measurement interval (i.e., the start time of the (i+1)th cycle measurement interval). Under the extension method, the number of executions of the measurement sequence within the i-th cycle measurement interval is usually increased by one. In this case, the amount of delay in the actual start time of the (i+1)th cycle measurement interval (i.e., the amount of extension of the i-th cycle measurement interval) will be shorter than the cycle time applied to the i-th cycle measurement interval.

[0023] If 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. The processor then selects a method to determine the actual end time of the i-th cycle measurement interval based on the difference time. In this case, the difference time may be compared with other times. Other times include the cycle time applied to the (i+1)th cycle measurement interval, the extension amount if the above extension method is adopted, a pre-set threshold, etc. The above measurement end time is the expected measurement end time if the measurement sequence is repeated more times without exceeding the end time of the i-th cycle measurement interval.

[0024] If the first method is selected as described above, the processor sets the actual end time of the i-th cycle measurement interval to be earlier than the actual end time of the i-th cycle measurement interval. In other words, the pre-filling method is implemented. On the other hand, if the second method is selected as described above, the processor sets the actual end time of the i-th cycle measurement interval to be later than the actual end time of the i-th cycle measurement interval. In other words, the extension method is implemented.

[0025] In the embodiment, the processor has a function to perform a correction mode and a function to perform a non-correction mode. In the correction mode, the start and end times of each cycle measurement interval are corrected so that no blank period occurs, thereby determining the actual start and end times of each cycle measurement interval. In the non-correction mode, the start and end times of each cycle measurement interval are used as they are, without correction.

[0026] The above configuration allows for the acquisition of advantages through correction of the cycle measurement interval, while preventing the occurrence of disadvantages resulting from such correction. The former advantage is the prevention of sample point loss. The latter disadvantage is a significant discrepancy between the planned cycle measurement interval and the actual cycle measurement interval.

[0027] In the embodiment, the processor selects either 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 less than a threshold, and selects the non-correction mode when the cycle time is greater than the threshold. In the embodiment, the cycle time corresponds to the upper limit of the correction amount. If the upper limit of the correction amount is greater than the threshold, the execution of the correction mode is restricted.

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

[0029] The mass spectrometry method according to this embodiment includes a setting step and a correction step. In the setting step, multiple cycle measurement intervals are set on the retention time axis based on multiple compound peak observation periods set on the retention time axis. In the correction step, the actual start time and end time of each cycle measurement interval are determined 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.

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

[0031] (2) Details of the embodiment Figure 1 shows an example configuration 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 the mass spectrometer. The mass spectrometer 14 operates according to an operating mode selected from among multiple operating modes. The multiple operating modes include scan mode, SIM mode, and SRM mode. The configuration and operation of the mass spectrometry system 10 will be described below assuming the execution of SRM mode.

[0032] The gas chromatograph 12 has columns for separating or extracting multiple compounds from a sample. The separated 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 spectrometer 20, a collision cell 22, a second mass spectrometer 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 that follows an electron ionization method. An ion source that follows another ionization method may be provided. In the ion source 18, each compound separated from the sample is ionized.

[0034] The first mass spectrometer 20 is composed of, for example, a quadrupole mass spectrometer. The first mass spectrometer 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 a quadrupole and contains a collision gas inside. Ions (precursor ions) collide with the collision gas, causing dissociation in the ions and generating product ions. In this embodiment, the collision cell 22 repeatedly accumulates ions and discharges the accumulated ions during the 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 composed of, 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 and voltage signals are 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. 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 comprised of a computer. The information processing device 16 has a processor 30 and a memory 34. The processor 30 is comprised of 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 device 38. The input device 36 is comprised of a keyboard, a pointing device, etc. The display device 38 is comprised of 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 functions to control the operation of the mass spectrometer 14, as well as functions to set multiple compound peak observation periods, set multiple measurement intervals (multiple cycle measurement intervals) based on the multiple compound peak observation periods, and correct multiple measurement intervals. In Figure 1, the function to correct multiple measurement intervals is represented as a correction unit 42.

[0039] The calculation unit 41 has a mass spectrum generation function, a chromatogram generation function, etc. The display unit 38 displays the mass spectrum, chromatogram, etc. Using the input unit 36, the user can input a cycle time or target cycle time that is commonly applied across multiple measurement intervals, or a cycle time or target cycle time for each measurement interval. The target cycle time serves as a reference value when automatically setting the cycle time considering various conditions.

[0040] The mass spectrometer (i.e., the mass spectrometer 14 and the information processing device 16) according to this embodiment 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 plurality of corrected 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.

[0041] 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 multiple compound peak observation periods. The measurement interval table 46 is a table for managing multiple measurement intervals (multiple cycle measurement intervals) set based on multiple compound peak observation periods.

[0042] In correction mode, the correction unit 42 corrects the time length of each measurement interval so that it becomes an integer multiple of the period of the cycle measurement performed in that measurement interval. In other words, the start and end times of each measurement interval are corrected so that no blank time occurs. This determines the actual start and end times of each measurement interval.

[0043] The start time is the planned start time, i.e., the uncorrected start time. The end time is the planned end time, i.e., the uncorrected end time. The actual start time is the corrected start time, and the actual end time is the corrected end time. In uncorrected mode, the start and end times of each measurement interval are used as they are. In this case, a time difference shorter than the cycle measurement period usually occurs between the end time and the actual end time of each measurement interval, which can be called excess time. Excess time will be explained in detail later.

[0044] Figure 2 shows an example of a compound table 44. The compound table 44 has multiple records 48 corresponding to multiple compounds separated from the sample. Each record 48 contains information 50 that identifies the compound, information 52 that indicates the expected appearance time of the compound peak, information 54 that indicates the start time of the compound peak observation period, information 56 that indicates the end time of the compound peak observation period, information 58 that indicates the mass-to-charge ratio of the precursor ion, information 60 that indicates the mass-to-charge ratio of the product ion, etc.

[0045] The combination of the mass-to-charge ratio of the precursor ion and the mass-to-charge ratio of the product ion is a transition 61. A single record 48 typically contains multiple transitions 61. For example, it may include one transition corresponding to the quantitative ion and one or more transitions corresponding to the confirmation ion.

[0046] In each record 48, the expected time of compound peak appearance, 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 user specifications.

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

[0048] Each record 62 includes information 64 that identifies the measurement interval, information 66 indicating the start time, information 68 indicating the end time, information 70 indicating the corrected start time (actual start time), information 72 indicating the corrected end time (actual end time), information 74 indicating the repeat period (cycle time) of the measurement sequence, etc. A cycle time is defined for each measurement interval, or a common cycle time is defined across multiple measurement intervals. The cycle time may be specified by the user or it may be determined automatically.

[0049] In correction mode, the actual start and end times are calculated and registered in the measurement interval table 46. These may also be registered in other tables. In non-correction mode, the actual start and end times are not calculated.

[0050] Figure 4 illustrates the setting of multiple measurement intervals based on the observation periods of multiple compound peaks, and the multiple remaining time intervals that occur within these intervals. In Figure 4, the horizontal axis represents the retention time (RT) axis. Note that Figure 4 does not reflect the ion time of flight, or delay time, in the mass spectrometer.

[0051] Chromatogram 76 contains multiple compound peaks 84, 86, and 88. The symbol 78 indicates a group of compound peak observation periods. This group 78 consists of three compound peak observation periods 90, 92, and 94. For example, compound peak observation period 90 is a period that extends in both the positive and negative directions around the predicted appearance time RT1, with the extent of the extension in each direction being ΔRT1. Measurement conditions for measuring compound ions are associated with each compound peak observation period 90, 92, and 94.

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

[0053] Based on the compound peak observation period group 78, a measurement interval group 80 is set. Specifically, based on the delimiter times C1 to C6 defined by multiple start times A1 to A3 and multiple 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 measurement interval Sa1 to Sa5 is before correction.

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

[0055] Reference numeral 82 indicates five packet sequences corresponding to five measurement intervals Sa1 to Sa5. Each packet sequence consists of multiple packets 96,98 that are consecutive on the holding 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 measurement sequence consists of multiple ion detection operations to detect multiple types of ions. Each ion detection operation includes one or more ion accumulation and discharge operations in the collision cell.

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

[0057] Since the measurement interval group 80 is defined based on the compound peak observation period group 78, the duration of each measurement interval Sa1 to Sa5 is usually not an integer multiple of the cycle time applied to that measurement interval. Dividing the duration of each measurement interval by the cycle time applied to that measurement interval yields a quotient Q and a remainder R. The quotient Q corresponds to the number of times the measurement sequence is executed. The remainder R corresponds to the remainder time. At the end of each measurement interval Sa1 to Sa5, a remainder time r1 to r5, shorter than the cycle time, inevitably occurs. The remainder time r1 to r5 is the time during which no ion measurements are performed, and is a blank period.

[0058] Reference numeral 104 indicates the plotting timing. Multiple detection values ​​corresponding to multiple types of ions, obtained during a single measurement sequence, are plotted on the chromatographic coordinate system. Typically, multiple detection values ​​obtained during a single measurement sequence are plotted on the same horizontal coordinate (reference time). If there is excess time r1~r5, the plotting interval will temporarily widen due to its influence. This degrades the quality of the compound peak waveform.

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

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

[0061] The actual start time Xb1 of the first measurement interval Sb1 is the same as the pre-correction start time Xa1. 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 (pre-correction end time) 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 from that division by the cycle time. Alternatively, it can be determined by subtracting the remainder from the pre-correction end time Ya1.

[0062] Note that the end time of the first measurement interval is corrected, but the start time of the first measurement interval is maintained. Focusing on this point, it may be understood that a special or exceptional process is applied only to the first measurement interval. Under this understanding, each subsequent measurement interval becomes subject to its original correction.

[0063] The actual start and end times for each measurement interval from the second onward are calculated as follows. In the following, i is an integer greater than or equal to 2.

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

[0065] By repeating the above calculation while increasing i by one, the start times Xa2 to Xa5 and end times Ya2 to Ya5 are corrected sequentially 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 sequentially from the second measurement interval to the last measurement interval (see reference numeral 123).

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

[0067] The above correction eliminates excess time and simultaneously increases the measurement time. Reference numeral 122 indicates the plotting timing of multiple detected values. The above correction prevents the problem of the plotting interval locally increasing due to the influence of excess time. In other words, it improves the quality of the displayed compound peak waveform.

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

[0069] In S10, the count value k is initialized, that is, 1 is assigned to k. k is an integer greater than or equal to 1. In S12, it is determined whether k is greater than 1 or not. If k=1, S16 is executed. For example, for the first measurement interval, in S16, the start time before correction is considered the actual start time, and the actual end time is determined based on the actual start time and cycle time.

[0070] For the second and subsequent measurement intervals, S14 is executed. In S14, the actual start time of the kth measurement interval is determined based on the actual end time of the k-1th measurement interval. Specifically, the actual start time of the kth measurement interval is set to match the actual end time of the k-1th measurement interval. Then, in S16, the actual end time of the kth measurement interval is determined based on the actual start time and cycle time.

[0071] In S18, the actual start time and 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 k is incremented by one, and each step from S12 onwards is executed again. If k has reached the maximum value kmax, in S22 the measurement of the sample is performed. The maximum value kmax is stored in memory 34.

[0072] Figure 7 shows the compound peak 144 related to the comparative example. The horizontal axis is the retention time axis, and the vertical axis is the intensity axis. Each point 146 represents the detected value. There is a time delay 148 between one measurement interval 140 and the next measurement interval 142. The reference numeral 150 indicates the plot interval within measurement interval 140. This plot interval is the same as the plot interval in the next measurement interval 142. Due to the influence of the time delay 148, a large plot interval 152 occurs within the compound peak 144. Plot interval 152 is larger than plot interval 150. At the location where the large plot interval 152 occurs, the smoothness of the waveform is reduced (see reference numeral 145).

[0073] Figure 8 shows compound peak 144A according to the embodiment. The horizontal axis is the retention time axis, and the vertical axis is the intensity axis. Due to the exclusion of excess time, the plot interval 152A at the transition between the two measurement intervals is the same as the plot interval 150. Compound peak 144A is smoothed across its entirety.

[0074] As shown in Figure 9, in the mass spectrometer according to this embodiment, a correction mode and a non-correction mode are selected depending on the situation. Specifically, when a common cycle time is defined across multiple measurement intervals, the correction mode or non-correction mode is selected based on that common cycle time.

[0075] In S30, the common cycle time Ct is compared with the threshold Ct1. If the common cycle time Ct is less than the threshold Ct1, the correction mode is executed in S32. In the correction mode, as already explained, the start and end times of each measurement interval are corrected. On the other hand, if the common cycle time Ct is greater than the threshold Ct1, the non-correction mode is executed in S34. In the non-correction mode, the start and end times of each measurement interval are used as they are.

[0076] When the common cycle time is large, uniformly excluding excess time results in a large correction amount, leading to a problem where the corrected measurement interval group differs significantly from the planned measurement interval group. As shown in Figure 9, if a correction mode or non-correction mode is selected according to the size of the common cycle time, it is possible to exclude excess time as long as the above problem does not occur.

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

[0078] Next, we will describe some variations. Figure 10 shows the extension method as the first variation. Figure 11 shows the selection method as the second variation. In Figures 10 and 11, elements similar to those shown in Figure 4 are denoted by the same reference numerals, and their descriptions are omitted.

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

[0080] First, the first measurement interval Sa1 is processed. The pre-correction start time Xa1 is set as the actual start time Xb1. The quotient P is obtained by dividing the time length from the actual start time Xb1 to the pre-correction end time Ya1 by the cycle time applied to the first measurement interval Sa1. Adding 1 to P and multiplying (P+1) by the cycle time determines the actual end time Yb1. The actual end time Yb1 is later than the pre-correction end time Ya1 by the extension amount.

[0081] The second and subsequent measurement intervals are processed as follows: i is an integer greater than or equal to 2.

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

[0083] By repeating the above calculation while increasing i by one, the start times Xa2-Xa5 and end times Ya2-Ya5 are corrected sequentially from the second measurement interval to the last measurement interval. That is, the actual start times Xb2-Xb5 and actual end times Yb2-Yb5 for each measurement interval are identified sequentially from the second measurement interval to the last measurement interval (see reference numeral 129). The multiple packets shown in gray represent packets (measurement sequences) added under the extension scheme.

[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 another 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-padding 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-padding 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 the 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 the actual end time of each measurement section are determined (see 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 the end time of each cycle measurement section are optimized. When the pre-padding 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 the 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. The cycle measurement in that case 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 the observation periods of multiple compound peaks set on the retention time axis, A second table for managing a plurality of cycle measurement intervals set on the retention time axis based on the plurality of compound peak observation periods, A processor that determines the actual start and end times of each cycle measurement interval by correcting the start and end times of each cycle measurement interval so that no blank period occurs between two temporally adjacent cycle measurement intervals, Includes, Each of the aforementioned cycle measurement intervals is a period during which a measurement sequence for detecting multiple types of ions in a time-resolved manner is repeatedly executed. The aforementioned processor, While increasing i by one each time (where i is an integer greater than or equal to 2), Based on the actual end time of the (i-1)th cycle measurement interval, the actual start time of the i-th cycle measurement interval is determined. The actual end time of the i-th cycle measurement interval is determined according to the actual start time of the i-th cycle measurement interval and the cycle time, which is the repetition period of the measurement sequence applied to the i-th cycle measurement interval. A mass spectrometer characterized by the following features.

2. In the mass spectrometer according to claim 1, The actual start time of the i-th cycle measurement interval is the same as the actual end time of the i-1 cycle measurement interval. A mass spectrometer characterized by the following features.

3. In the mass spectrometer according to claim 1, The aforementioned processor, The actual end time of the i-th cycle measurement interval is set to be earlier than the end time of the i-th cycle measurement interval. A mass spectrometer characterized by the following features.

4. In the mass spectrometer according to claim 1, The aforementioned processor, The actual end time of the i-th cycle measurement interval is set to be later than the end time of the i-th cycle measurement interval. A mass spectrometer characterized by the following features.

5. In the mass spectrometer according to claim 1, The aforementioned processor, The difference time between the predicted end time of measurement within the i-th cycle measurement interval and the start time of the (i+1)-th cycle measurement interval is calculated. A method is selected to determine the actual end time of the i-th cycle measurement interval based on the aforementioned difference time. A mass spectrometer characterized by the following features.

6. In the mass spectrometer according to claim 5, The aforementioned processor, If the first method is selected as the aforementioned method, the actual end time of the i-th cycle measurement interval is set to be earlier than the end time of the i-th cycle measurement interval. If the second method is selected as the aforementioned method, the actual end time of the i-th cycle measurement interval is set to be later than the end time of the i-th cycle measurement interval. A mass spectrometer characterized by the following features.

7. In the mass spectrometer according to claim 1, The processor has a function to perform a correction mode and a function to perform a non-correction mode. In the correction mode, the actual start and end times of each cycle measurement interval are determined by correcting the start and end times of each cycle measurement interval so that the blank period does not occur. In the aforementioned uncorrected mode, the start and end times of each cycle measurement interval are used as they are without correction. A mass spectrometer characterized by the following features.

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

9. In the mass spectrometer according to claim 8, The aforementioned processor, The correction mode is selected when the cycle time is less than the threshold. The uncorrected mode is selected when the cycle time is greater than the threshold. A mass spectrometer characterized by the following features.

10. In the mass spectrometer according to any one of claims 1 to 9, A first mass spectrometer that applies first-order mass spectrometry to ions generated from a sample, A collision cell for accumulating and discharging ions that have passed through the first mass spectrometer, A second mass spectrometer that applies second mass spectrometry to ions discharged from the collision cell, A detector for detecting ions that have passed through the second mass spectrometer, Includes, The processor controls the operation of the first mass spectrometer, the collision cell, and the second mass spectrometer according to the measurement sequence applied to each cycle measurement period. A mass spectrometer characterized by the following features.

11. A step of setting multiple cycle measurement intervals on the retention time axis based on multiple compound peak observation periods set on the retention time axis, The process of determining the actual start and end times of each cycle measurement interval by correcting the start and end times of each cycle measurement interval so that no blank period occurs between two temporally adjacent cycle measurement intervals, Includes, Each of the aforementioned cycle measurement intervals is a period during which a measurement sequence for detecting multiple types of ions in a time-resolved manner is repeatedly executed. In the process of determining the actual start time and actual end time of each cycle measurement interval, While increasing i by one each time (where i is an integer greater than or equal to 2), Based on the actual end time of the (i-1)th cycle measurement interval, the actual start time of the i-th cycle measurement interval is determined. The actual end time of the i-th cycle measurement interval is determined according to the actual start time of the i-th cycle measurement interval and the cycle time, which is the repetition period of the measurement sequence applied to the i-th cycle measurement interval. A mass spectrometry method characterized by the following features.

12. A program executed in an information processing device, A function to set multiple cycle measurement intervals on the retention time axis based on multiple compound peak observation periods set on the retention time axis, A function to determine the actual start and end times of each cycle measurement interval by correcting the start and end times of each cycle measurement interval so that no blank period occurs between two temporally adjacent cycle measurement intervals, Includes, Each of the aforementioned cycle measurement intervals is a period during which a measurement sequence for detecting multiple types of ions in a time-resolved manner is repeatedly executed. When the function that determines the actual start time and actual end time of each cycle measurement interval is executed, While increasing i by one each time (where i is an integer greater than or equal to 2), Based on the actual end time of the (i-1)th cycle measurement interval, the actual start time of the i-th cycle measurement interval is determined. The actual end time of the i-th cycle measurement interval is determined according to the actual start time of the i-th cycle measurement interval and the cycle time, which is the repetition period of the measurement sequence applied to the i-th cycle measurement interval. A program characterized by the following features.

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