Malfunctioning location inference method and liquid chromatograph

Abstract

To infer a malfunctioning consumable from among a plurality of consumables in a plunger pump or to infer a malfunctioning plunger pump from among the plurality of plunger pumps.SOLUTION: A liquid chromatograph 100 includes: a double-plunger pump 6 having a first plunger pump 9a, a second plunger pump 10a, and a plurality of consumables 11a to 14a; a pressure sensor 8a that detects a pressure of a solvent discharged by the double-plunger pump 6; a dispensing unit 2; a separation column 3; and a control unit 16 that infers a malfunctioning consumable among the plurality of consumables, on the basis of a first pressure detected by the pressure sensor 8a in a first section in which the first plunger pump 9a discharges the solvent into a channel 101 and a second pressure detected by the pressure sensor 8a in a second section in which the second plunger pump 10a discharges the solvent into the channel 101.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a fault location estimation method and a liquid chromatograph. [Background technology]

[0002] An apparatus used in liquid chromatography analysis is called a liquid chromatograph. In general, a liquid chromatograph is equipped with a liquid delivery pump, a dispensing unit for introducing a sample into the liquid chromatograph, a separation column, a detector, a waste liquid container, and a system control unit for controlling them. In general, a liquid delivery pump used in a liquid chromatograph has a configuration in which two plunger pumps are connected in series. This is called a double plunger pump. The upstream plunger pump (first plunger pump) draws in, compresses, and discharges the solvent. Since the first plunger pump alone cannot deliver a constant flow rate, another plunger pump (second plunger pump) is connected downstream. The second plunger pump operates to cancel the pulsating flow of the first plunger pump (discharges the solvent when the first plunger pump draws in and compresses the solvent), so that the liquid delivery pump as a whole can deliver a constant flow rate.

[0003] Furthermore, in order to perform more sophisticated liquid chromatography, a method called high-pressure gradient liquid delivery is commonly used. This is a method in which two sets of the above-mentioned double plunger pumps are connected in parallel, and different solvents (e.g., water and an organic solvent) are delivered from each, allowing the mixing ratio of the solvents to be freely manipulated. Therefore, a total of four plunger pumps are required to perform high-pressure gradient liquid delivery.

[0004] In addition, each plunger pump is equipped with a plunger seal to prevent leakage from the plunger. Also, check valves are installed on the inlet and outlet sides of the plunger pump upstream of the double plunger pump to prevent backflow. The plunger seals and check valves are consumable parts and deteriorate due to wear, etc.

[0005] In addition, to check whether liquid chromatography analysis is being performed correctly, a known internal standard substance may be mixed into the sample in advance, separate from the substance to be analyzed. This is generally called the internal standard method. By checking the detection intensity and detection time of the internal standard substance, it is possible to check that the device is functioning properly.

[0006] In a general known example, an abnormality in a liquid chromatograph is detected and the fault location is estimated by monitoring a pressure gauge installed in the liquid delivery pump or a signal from an internal standard substance. If it is estimated that the fault is in the liquid delivery pump, in many cases, consumable parts are replaced. Patent Document 1 discloses a method of detecting an abnormality in each unit using a flow meter installed in the liquid delivery pump and an actinometer installed in the detection unit. Patent Document 2 discloses a method of detecting pressure pulsation based on a pressure gauge attached to the liquid delivery pump and stopping the device. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2017-156093 A [Patent Document 2] International Publication No. 2020 / 183774 Summary of the Invention [Problem to be solved by the invention]

[0008] Generally, if it is assumed that the failure is in the liquid delivery pump, in most cases the consumable parts are replaced. However, since it is not possible to determine which part of the liquid delivery pump is at fault, if a failure in the liquid delivery pump is suspected, all of the consumable parts are often replaced, which poses the problem of increased parts costs. In particular, in the case of a liquid delivery pump with high-pressure gradient function, there are four plunger pumps, so replacing all of the consumable parts would be expensive and would take a long time to complete.

[0009] Therefore, an object of the present disclosure is to estimate which consumable item has failed among a plurality of consumable items in a plunger pump, or to estimate which plunger pump has failed among a plurality of plunger pumps. [Means for solving the problem]

[0010] The fault location estimation method disclosed herein is a fault location estimation method for estimating the fault location of a liquid chromatograph, and includes the steps of discharging a solvent into a flow path by a double plunger pump having a first plunger pump, a second plunger pump arranged downstream of the first plunger pump, and a plurality of consumables related to the discharge of the solvent, introducing a sample into the flow path, detecting the pressure of the solvent discharged by the double plunger pump, separating the sample into its components by a separation column, detecting each of the components separated by the separation column, and estimating a faulty consumable among the plurality of consumables based on a first pressure detected in a first section where the first plunger pump discharges the solvent into the flow path and a second pressure detected in a second section where the second plunger pump discharges the solvent into the flow path.

[0011] The liquid chromatograph of the present disclosure also includes a double plunger pump having a first plunger pump, a second plunger pump arranged downstream of the first plunger pump, and a plurality of consumables related to the discharge of a solvent, a pressure sensor detecting the pressure of the solvent discharged by the double plunger pump, a dispensing unit introducing a sample into a flow path, a separation column connected downstream of the dispensing unit for separating the sample into its components, a detection unit detecting each of the components separated by the separation column, and a control unit estimating a faulty consumable among the plurality of consumables based on a first pressure detected by the pressure sensor in a first section where the first plunger pump discharges the solvent into the flow path and a second pressure detected by the pressure sensor in a second section where the second plunger pump discharges the solvent into the flow path.

[0012] The fault location estimation method disclosed herein is a fault location estimation method for estimating the fault location of a liquid chromatograph, and includes the steps of mixing multiple types of solvents using multiple plunger pumps and discharging them into a flow path, introducing a sample into the flow path, separating the sample into its components using a separation column, detecting each of the components separated by the separation column, obtaining the retention time of an internal standard substance supplied to the flow path when detecting the sample components, and comparing the retention time with a predetermined value to determine whether the retention time is ahead or behind, and estimating which plunger pump among the multiple plunger pumps is faulty based on the retention time determination result.

[0013] The liquid chromatograph of the present disclosure also includes a plurality of plunger pumps that mix a plurality of types of solvents and discharge them into a flow path, a dispensing unit that introduces a sample into the flow path, a separation column connected downstream of the dispensing unit that separates the sample into its components, a detection unit that detects each component separated by the separation column, and a control unit that, when detecting the components of the sample, acquires a retention time of an internal standard substance supplied to the flow path, compares the retention time with a predetermined value to determine whether the retention time is ahead or behind, and estimates which of the plurality of plunger pumps is faulty based on the retention time determination result. Effect of the Invention

[0014] According to the present disclosure, it is possible to estimate a faulty consumable item from among multiple consumable items in a plunger pump, or to estimate a faulty plunger pump from among multiple plunger pumps. As a result, it is expected that the cost of parts can be reduced and the time required for recovery work can be shortened. Problems, configurations, and effects other than those described above will be made clear in the following description of the embodiments. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a liquid chromatograph according to a first embodiment. [Diagram 2] 11 is a graph showing the displacement of each plunger when a solvent is normally pumped by the first double plunger pump. [Diagram 3]FIG. 11 is a diagram showing transitions between sections during normal liquid delivery by a first double plunger pump and a second double plunger pump. [Figure 4] 4 shows an example of the measurement results when a sample is measured by the liquid chromatograph of Example 1. [Diagram 5] FIG. 2 is a diagram showing a reference table held by the liquid chromatograph of Example 1. [Figure 6] 4 is a flowchart for estimating a fault location of a liquid delivery pump in the liquid chromatograph of the first embodiment. [Figure 7] 4 is an example of measurement results when an abnormality occurs when a sample is measured by the liquid chromatograph of Example 1. [Figure 8] 13 is actual data of a pressure sensor of the first double plunger pump. [Figure 9] FIG. 1 is a schematic diagram showing the configuration of a liquid chromatograph according to a second embodiment. [Figure 10] 13 is a flowchart for estimating a fault location of a liquid delivery pump in the liquid chromatograph of Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, the components (including element steps, etc.) are not necessarily essential unless otherwise specified or considered to be obviously essential in principle.

[0017] Example 1 <Configuration example of liquid delivery pump and liquid chromatograph> FIG. 1 is a schematic diagram showing the configuration of a liquid chromatograph of Example 1. As shown in FIG. 1, the liquid chromatograph 100 includes a first double plunger pump 6, a second double plunger pump 7, a dispensing unit 2, a separation column 3, a detection unit 4, a waste liquid container 5, and a control unit 16 that controls them. The dispensing unit 2 introduces a sample 1 into the liquid chromatograph 100 (flow path 101). The separation column 3 is connected downstream of the dispensing unit 2 and separates the sample 1 into each component. The detection unit 4 detects each component separated by the separation column 3 and creates a chromatogram. The waste liquid container 5 is a container for discarding the measured solvent and sample. The dispensing unit 2, the separation column 3, the detection unit 4, and the waste liquid container 5 can be those generally used in liquid chromatographs, so their detailed configurations will not be described in detail.

[0018] The liquid chromatograph 100 of the first embodiment performs liquid chromatography using a liquid delivery method called high-pressure gradient liquid delivery. To this end, in the liquid chromatograph 100, a plurality of types of solvents are mixed and discharged into a flow path by a plurality of plunger pumps (a first double plunger pump 6 and a second double plunger pump 7) connected in parallel. For example, the first double plunger pump 6 discharges water contained in a solvent bottle 15a, and the second double plunger pump 7 discharges an organic solvent (e.g., methanol) contained in a solvent bottle 15b.

[0019] <First double plunger pump 6> The first double plunger pump 6 includes a pressure sensor 8a, a first plunger pump 9a, a second plunger pump 10a, and a number of consumables related to the discharge of the solvent. The first plunger pump 9a and the second plunger pump 10a are connected in series, with the first plunger pump 9a disposed on the upstream side and the second plunger pump 10a disposed on the downstream side.

[0020] The pressure sensor 8a is disposed downstream of the second plunger pump 10a. The pressure sensor 8a measures the pressure (discharge pressure) of the solvent (liquid) discharged from the second plunger pump 10a, and outputs the pressure value to the control unit 16.

[0021] The control unit 16 controls the operations of the first plunger pump 9a and the second plunger pump 10a by giving command values ​​to these pumps, based on the discharge pressure measured by the pressure sensor 8a and a predetermined operation sequence.

[0022] The first plunger pump 9a has a first check valve 13a, a second check valve 14a, and a first seal 11a. The first check valve 13a is disposed in a flow path of a suction port of the first plunger pump 9a, and the second check valve 14a is disposed in a flow path of a discharge port of the first plunger pump 9a. The first check valve 13a and the second check valve 14a restrict the flow of the solvent. The first seal 11a prevents leakage of the liquid from the first plunger pump 9a.

[0023] The second plunger pump 10a has a second seal 12a. The second seal 12a prevents leakage of liquid from the second plunger pump 10a.

[0024] A solvent (for example, water) contained in a solvent bottle 15a is pushed out by a first plunger pump 9a and a second plunger pump 10a, and is supplied to the dispensing section 2 and the separation column 3 downstream.

[0025] <Second double plunger pump 7> The second double plunger pump 7 has the same configuration as the first double plunger pump 6, and includes a pressure sensor 8b, a first plunger pump 9b, a second plunger pump 10b, a first seal 11b, a second seal 12b, a first check valve 13b, and a second check valve 14b. A solvent (e.g., methanol) contained in a solvent bottle 15b is pushed out by the first plunger pump 9b and the second plunger pump 10b, and is supplied to the downstream dispensing section 2 and separation column 3. A detailed description of the second double plunger pump 7 is omitted because it is similar to that of the first double plunger pump 6.

[0026] The solvent discharged from the first double plunger pump 6 and the solvent discharged from the second double plunger pump 7 are joined at the joining section 102 and mixed at a desired concentration ratio. As a result, in the liquid chromatograph 100 of the first embodiment, the components in the sample 1 can be separated and eluted while continuously changing the concentration ratio of the eluents (water, methanol).

[0027] In this specification, the "lower limit" refers to the lowest position within the range in which the plunger pumps (9a, 9b, 10a, 10b) can move within the pressurized chamber. On the other hand, the "upper limit" refers to the highest position within the range in which the plunger pumps (9a, 9b, 10a, 10b) can move within the pressurized chamber. Furthermore, the "ascension" of the plunger pumps (9a, 9b, 10a, 10b) refers to movement in the direction in which the solvent in the pressurized chamber is compressed or discharged, and the "descent" of the plunger refers to movement in the direction in which the solvent is sucked into the pressurized chamber.

[0028] The solvent contained in the solvent bottle 15a is pushed out by the first plunger pump 9a and the second plunger pump 10a of the first double plunger pump 6 and supplied to the dispensing section 2. The solvent contained in the solvent bottle 15b is pushed out by the first plunger pump 9b and the second plunger pump 10b of the second double plunger pump 7 and supplied to the dispensing section 2. The sample 1 to be analyzed is injected into the solvent supplied to the dispensing section 2. The solvent into which the sample 1 is injected is introduced into the separation column 3 and separated into individual components. The detection section 4 then detects the absorbance, fluorescence intensity, refractive index, and the like according to the sample components. The separation column 3 is a reversed-phase column. The separation column 3 may be a normal-phase column. This separation column 3 is filled with microparticles, and a load pressure of several tens of megapascals to more than a hundred megapascals is generated in the double plunger pump (6, 7) due to the fluid resistance when the solvent flows through the gaps between the microparticles. The magnitude of this load pressure varies depending on the diameter of the separation column 3 and the flow rate passing through it.

[0029] <Control unit 16> The control unit 16 has a processor 17, a main memory unit 18, an auxiliary memory unit 19, and an interface 20. The processor 17 is a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), an ASIC, or the like. The main memory unit 18 is a dynamic random access memory (DRAM) or the like, and is used as a working area for the processor 17. The auxiliary memory unit 19 is a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof, and stores various programs and various data. The interface 20 is a device controller that controls the operation of the first double plunger pump 6, the second double plunger pump 7, and the like, which are connected to the control unit 16, a monitor interface that outputs a video signal to the display unit 21, and a network controller that performs communication control.

[0030] For example, the auxiliary storage unit 19 stores a program for estimating a faulty double plunger pump from among a plurality of double plunger pumps (6, 7) and estimating a faulty consumable item from among a plurality of consumable items in the estimated faulty double plunger pump. The auxiliary storage unit 19 also stores a reference table 500 (see FIG. 5) that is referenced when the above-mentioned program is executed. The reference table 500 may be stored in the auxiliary storage unit 19 inside the control unit 16, or may be stored in a storage unit outside the control unit 16.

[0031] <Liquid delivery method> An outline of a method for normally delivering a solvent using the first double plunger pump 6 of the first embodiment will be described. Here, "normal delivery" refers to a method for delivering a solvent discharged from the first double plunger pump 6 to the dispensing section 2, the separation column 3, and the detection section 4 to analyze the sample 1. In addition, since the first double plunger pump 6 and the second double plunger pump 7 shown in FIG. 1 have the same device configuration, a description of the delivery method by the second double plunger pump 7 will be omitted. Note that the second double plunger pump 7 performs the same operation as the first double plunger pump 6, but with a delay of half a cycle.

[0032] Fig. 2 is a graph showing the displacement of each plunger when the first double plunger pump 6 normally pumps a solvent. In both of the two graphs shown in Fig. 2, the horizontal axis indicates time, and the vertical axis indicates, from the top, the displacement of the first plunger pump 9a and the displacement of the second plunger pump 10a. The upward direction of the displacement of the first plunger pump 9a and the displacement of the second plunger pump 10a is defined as the positive direction, and the downward direction is defined as the negative direction. In normal liquid pumping, both the first plunger pump 9a and the second plunger pump 10a operate based on the lower limit point.

[0033] In normal liquid delivery, both the first plunger pump 9a and the second plunger pump 10a operate periodically. Two periods are shown in Fig. 2. The drive period a is composed of four sections b, c, d, and e, and is repeated in this order. The length of the drive period a is, for example, 2 seconds, 4 seconds, 6 seconds, etc. Each section will be explained.

[0034] Section b is called the section where only the second plunger pump 10a delivers the amount of liquid delivered that is specified by the user of the device. The first plunger pump 9a moves to the lower limit and then stops until section b ends. The first plunger pump 9a is displaced in the negative direction, but because the second check valve 14a closes the flow path, the movement of the first plunger pump 9a does not affect the delivery flow rate.

[0035] Section c is called the compression section. In this section, the second plunger pump 10a discharges the amount of liquid sent specified by the device user. The control unit 16 calls up the stored compression ratio parameters and calculates the amount of solvent compression (plunger displacement) required for compression by the first plunger pump 9a together with the pressure value received from the pressure sensor 8a. Thereafter, under the control of the control unit 16, the first plunger pump 9a moves in the forward direction by the calculated compression amount. Until the pressure in the pressurizing chamber of the first plunger pump 9a exceeds the discharge pressure, the movement of the first plunger pump 9a does not affect the discharge flow rate because the second check valve 14a is closed.

[0036] Section d is called the cross liquid delivery section. In this section, the second plunger pump 10a moves to the lower limit. The first plunger pump 9a moves in the positive direction and discharges a flow rate value that is the sum of the flow rate for suction generated by the second plunger pump 10a moving in the negative direction and the flow rate specified by the device user. As a result, the first double plunger pump 6 as a whole discharges the liquid delivery amount specified by the device user.

[0037] Section e is called the section where the first plunger pump 9a pumps the liquid alone. In this section, the first plunger pump 9a pumps the amount of liquid specified by the user. The second plunger pump 10a stops until section e ends.

[0038] After the end of the single liquid sending section e by the first plunger pump 9a, the process moves to section b, and the same cyclic operation is repeated.

[0039] In the above sections b to e, it is important to note that in sections b and c, the second plunger pump 10a mainly delivers the liquid, and in sections d and e, the first plunger pump 9a mainly delivers the liquid. It is also important to note that different check valves are opened and closed in each section.

[0040] For example, if the first seal 11a of the first plunger pump 9a breaks down, liquid leakage occurs from the first plunger pump 9a, and the first plunger pump 9a cannot pump liquid. As a result, the amount of liquid pumped by the double plunger pump decreases in sections d and e, and the liquid pumping pressure decreases. After that, when the system moves to section b, the second check valve 14a closes the flow path and the second plunger pump 10a takes over the liquid pumping, so that the amount of liquid pumped by the double plunger pump 6 recovers to the flow rate specified by the device user, and the liquid pumping pressure also returns to its normal value.

[0041] Similarly, for example, if the first check valve 13a of the first plunger pump 9a breaks down, a backflow occurs from the first plunger pump 9a to the upstream, and the first plunger pump 9a cannot pump liquid. Therefore, in sections d and e, the amount of liquid pumped by the double plunger pump 6 decreases, and the liquid pumping pressure decreases. After that, when the system moves to section b, the second check valve 14a closes the flow path, and the second plunger pump 10a takes over the liquid pumping, so that the amount of liquid pumped by the double plunger pump 6 recovers to the flow rate specified by the device user, and the liquid pumping pressure also returns to its normal value.

[0042] For example, if the second check valve 14a of the first plunger pump 9a breaks down, a backflow occurs from the downstream second plunger pump 10a to the upstream first plunger pump 9a, so the second plunger pump 10a cannot pump liquid. Therefore, in sections b and c, the amount of liquid pumped by the double plunger pump 6 decreases, and the liquid pumping pressure decreases. After that, when the section moves to section d, the plunger pump that pumps liquid shifts from the second plunger pump 10a to the first plunger pump 9a. When the first plunger pump 9a pumps liquid, the second check valve 14a is in an open state as in the past, so even if the second check valve 14a breaks down and loses its valve function, it is possible to pump liquid in the same way as usual. Therefore, the amount of liquid pumped by the double plunger pump 6 is restored to the flow rate specified by the device user, and the liquid pumping pressure also returns to a normal value.

[0043] For example, if the second seal 12a of the second plunger pump 10a breaks down, the liquid delivery flow rate and liquid delivery pressure will decrease in all of sections b to e. This is because the inside of the cylinder of the second plunger pump 10a is also used when the first plunger pump 9a is delivering liquid, so liquid leakage will occur regardless of the timing when either pump is delivering liquid.

[0044] In this way, by checking in which section, from section b to section e, the pressure value drops, it is possible to identify the part that is most likely to be faulty.

[0045] FIG. 3 is a diagram showing the transition of sections during normal liquid delivery by the first double plunger pump 6 and the second double plunger pump 7. The two double plunger pumps 6 and 7 operate with a drive period a shifted by half a period. In other words, when the first double plunger pump 6 is in sections b and c, the second double plunger pump 7 is in sections d and e. Here, the period when the first double plunger pump 6 is in sections b and c, and the second double plunger pump 7 is in sections d and e, is called section f (first section). Conversely, the period when the first double plunger pump 6 is in sections d and e, and the second double plunger pump 7 is in sections b and c is called section g (second section).

[0046] <Internal standard method> 4 is an example of the measurement results when a sample is measured by the liquid chromatograph of Example 1. The horizontal axis indicates the elapsed time from the start of measurement, and the vertical axis indicates the detection value in the detection unit 4. There are three peaks in FIG. 4, which are, from the left, peaks derived from an internal standard, target material A, and target material B. An apparatus user uses liquid chromatograph 100 for the purpose of measuring target materials A and B.

[0047] The device user mixes a known internal standard substance at a known concentration with the sample to be measured and measures the sample. Then, as shown in FIG. 4, a detection peak originating from the internal standard substance appears. The retention time and peak height of the detection peak originating from the internal standard substance are stored in advance in the control unit 16, and by checking against these values, it is confirmed whether the liquid chromatograph 100 is operating normally. For example, in FIG. 4, the retention time of the internal standard substance is about 26 seconds, and it is confirmed whether this value is within a preset range of time stored in the control unit 16, for example, a range of 25 to 27 seconds, to ensure the normality of the device. If it is not within the preset range of time, the device user is notified of an abnormality in the device.

[0048] The retention time of the internal standard substance varies depending on the composition of the separation column 3 and the solvent ratio of the high-pressure gradient liquid delivery performed by the double plunger pumps 6 and 7, and the specified range of time is determined by prior experiments.

[0049] For example, a reversed-phase column may be used as the separation column 3, with water pumped from the first double plunger pump 6 and methanol pumped from the second double plunger pump 7. The internal standard and the ratio of water to methanol pumped will vary depending on the target substance to be measured. These are determined by the user of the device through prior consideration and experimentation.

[0050] Generally, a feature of a reversed-phase column is that the retention time becomes faster as the ratio of an organic solvent such as methanol increases, and the retention time becomes slower as the ratio of water increases. For example, when an internal standard substance is measured with a mixture ratio of 50% water and 50% methanol, if the retention time is 26 seconds, when the mixture ratio is 40% water and 60% methanol, the retention time will be 20 seconds. In this way, the retention time of the internal standard substance changes depending on the characteristics of the separation column 3 and the ratio of the solvents being pumped.

[0051] In a similar example, if the internal standard, which had a retention time of about 26 seconds in the past, were to lead by about 20 seconds, the amount of liquid delivered by the double plunger pump delivering water would decrease, and the ratio of methanol delivered would increase relatively. Conversely, if the retention time of the internal standard were to be delayed to about 30 seconds, the amount of liquid delivered by the double plunger pump delivering methanol would decrease, and the ratio of water delivered would increase relatively.

[0052] In this way, by focusing on the retention time of the internal standard, it is possible to identify a double plunger pump in which the liquid delivery rate is decreasing.

[0053] <Reference table> 5 is a diagram showing a reference table held by the liquid chromatograph of Example 1. Here, a reference table 500 stored in the auxiliary storage unit 19 of the control unit 16 will be described. The reference table 500 includes information on the section in which the pressure abnormality occurred, information on whether the retention time of the internal standard substance is ahead of or behind a specified range time, and information on the faulty consumable. The control unit 16 refers to the reference table 500 to estimate which consumable is faulty.

[0054] The reference table 500 is a data table assuming a configuration in which the separation column 3 is a reversed-phase column, the double plunger pump 6 discharges water, and the double plunger pump 7 discharges methanol. According to the reference table 500, if the retention time of the internal standard substance precedes a specified range of time, it is determined that the double plunger pump 6 has a malfunction. Also, if the retention time of the internal standard substance lags behind the specified range of time, it is determined that the double plunger pump 7 has a malfunction.

[0055] According to the reference table 500, if the retention time of the internal standard substance precedes the specified range time and the section in which the pressure abnormality occurs is only section f, it is determined that the second check valve 14a of the double plunger pump 6 has failed. If the retention time of the internal standard substance precedes the specified range time and the section in which the pressure abnormality occurs is only section g, it is determined that the first seal 11a or the first check valve 13a of the double plunger pump 6 has failed. If the retention time of the internal standard substance precedes the specified range time and the section in which the pressure abnormality occurs is section f and section g, it is determined that the second seal 12a of the double plunger pump 6 has failed.

[0056] According to the reference table 500, if the retention time of the internal standard is delayed beyond the specified range time and the section in which the pressure abnormality occurs is only section f, it is determined that the first seal 11b or the first check valve 13b of the double plunger pump 7 has failed. If the retention time of the internal standard is delayed beyond the specified range time and the section in which the pressure abnormality occurs is only section g, it is determined that the second check valve 14b of the double plunger pump 7 has failed. If the retention time of the internal standard is delayed beyond the specified range time and the section in which the pressure abnormality occurs is section f and section g, it is determined that the second seal 12b of the double plunger pump 7 has failed.

[0057] <Fault location estimation> Fig. 6 is a flowchart for estimating a fault location of a liquid delivery pump (the first double plunger pump 6 and the second double plunger pump 7 are collectively referred to as a liquid delivery pump) in the liquid chromatograph of Example 1. For example, each step of the flowchart in Fig. 6 is executed by the processor 17 of the control unit 16 executing a program for estimating a faulty consumable item.

[0058] Here, a reversed phase column is used for the separation column 3, water is pumped from the first double plunger pump 6, and methanol is pumped from the second double plunger pump .

[0059] <Example of fault location estimation> An example of an actual measurement of sample 1 using the liquid chromatograph configuration shown in FIG. 1 and an abnormality will be described below.

[0060] 7 shows an example of the measurement results when an abnormality occurs when a sample is measured by the liquid chromatograph of Example 1. The horizontal axis indicates the elapsed time from the start of the measurement, and the vertical axis indicates the detected value at the detection unit 4. The sample measured is the same as that shown in FIG.

[0061] According to the flow chart shown in Fig. 6, first, the control unit 16 measures the internal standard (step S601). Specifically, the first double plunger pump 6 and the second double plunger pump 7 discharge the solvent into the flow path 101, and introduce the sample 1 and the internal standard into the flow path 101. Then, the pressure sensors 8a and 8b detect the pressure of the solvent discharged by the first double plunger pump 6 and the second double plunger pump 7. Then, the separation column 3 separates the sample 1 into each component, and the detection unit 4 detects each component separated by the separation column 3. At this time, each component of the sample 1 and the components of the internal standard are measured.

[0062] When the measurement of the internal standard is completed, the control unit 16 checks the measurement result of the internal standard (step S602). The measurement result of the internal standard is checked to see whether the retention time, peak height, peak area, half width, or a combination thereof falls within a specified range stored in the control unit 16. The retention time, peak height, peak area, half width, or a combination thereof of the internal standard is called the feature amount of the internal standard.

[0063] If there is no abnormality in the characteristic amount of the internal standard (step S603: NO), the control unit 16 ends this flowchart (step S604). On the other hand, if there is an abnormality in the characteristic amount of the internal standard (step S603: YES), the control unit 16 determines whether or not there is an abnormality in the retention time (step S605).

[0064] In the measurement results shown in Fig. 7, the peak time of the internal standard is about 23 seconds, which is earlier than the normal peak time (about 26 seconds) of the internal standard in Fig. 4. In this embodiment, for example, the normal range of retention time is from 25 seconds to 27 seconds. In this case, the control unit 16 determines that the measurement result of the internal standard (peak time (about 23 seconds)) is abnormal (step S605: YES), and executes the process of step S607.

[0065] On the other hand, when the control unit 16 determines that the measurement result of the internal standard is not abnormal (step S605: NO), it suspects a malfunction other than that of the liquid delivery pump (step S606) and ends this flowchart (step S604).

[0066] The control unit 16 checks for a change in the retention time that is not within the normal range (step S607). In the example of FIG. 7, since the retention time is ahead of the predetermined value (step S607: ahead), the control unit 16 refers to the reference table 500 and determines that the first double plunger pump 6 is broken (step S608). On the other hand, if the retention time is behind the predetermined value (step S607: behind), the control unit 16 refers to the reference table 500 and determines that the second double plunger pump 7 is broken (step S609). When a reversed-phase column is used for the separation column 3 and the retention time is ahead, it is considered that the amount of water delivered is reduced and the ratio of methanol delivered is increased. Therefore, the first double plunger pump 6, which delivers water, is most likely to be broken. Also, when the retention time is delayed, it is considered that the amount of methanol delivered is reduced and the ratio of water delivered is increased. Therefore, the second double plunger pump 7, which delivers methanol, is most likely to be broken.

[0067] After determining that the first double plunger pump 6 is broken (step S608), the control unit 16 checks the value of the pressure sensor 8a of the first double plunger pump 6 and checks the section of the pressure abnormality (step S610). Figure 8 shows actual data of the pressure sensor 8a of the first double plunger pump 6. The horizontal axis represents time, and the vertical axis represents the pressure value.

[0068] According to Fig. 8, it can be seen that the pressure (second pressure) drops in section f and the pressure (first pressure) rises in section g. As described above, this indicates that the amount of liquid delivered by the second plunger pump 10a has decreased and the amount of liquid delivered by the first plunger pump 9a is normal. In the example of Fig. 8, since the control unit 16 has confirmed the pressure drop in section f, it concludes that a failure of the second check valve 14a of the first double plunger pump 6 is suspected (step S612).

[0069] Also, if it is confirmed that the pressure (second pressure) rises in section f and the pressure (first pressure) drops in section g, it can be determined that the amount of liquid sent by the first plunger pump 9a has decreased and the amount of liquid sent by the second plunger pump 10a is normal. Therefore, since the control unit 16 has confirmed the pressure drop in section g, it concludes that a failure of the first seal 11a or the first check valve 13a of the first double plunger pump 6 is suspected (step S613).

[0070] Furthermore, if it is confirmed that the pressure is dropping in all sections, it can be determined that the liquid delivery rate is decreasing as a whole in the first double plunger pump 6. Therefore, since the control unit 16 has confirmed the pressure drop in all sections, it concludes that a failure of the second seal 12a of the first double plunger pump 6 is suspected (step S614).

[0071] On the other hand, after determining that the second double plunger pump 7 has failed (step S609), the control unit 16 checks the value of the pressure sensor 8b of the second double plunger pump 7 and checks the section of the pressure abnormality (step S611).

[0072] If it is confirmed that the pressure drops in section f and rises in section g, it can be determined that the amount of liquid sent by the first plunger pump 9b has decreased and the amount of liquid sent by the second plunger pump 10b is normal. Therefore, since the control unit 16 confirmed the pressure drop in section f, it concludes that a failure of the first seal 11b or the first check valve 13b of the second double plunger pump 7 is suspected (step S615).

[0073] Furthermore, if it is confirmed that the pressure rises in section f and drops in section g, it can be determined that the amount of liquid delivered by the second plunger pump 10b has decreased and the amount of liquid delivered by the first plunger pump 9b is normal. Therefore, since the control unit 16 has confirmed the pressure drop in section g, it concludes that a failure of the second check valve 14a of the second double plunger pump 7 is suspected (step S616).

[0074] Furthermore, if it is confirmed that the pressure is dropping in all sections, it can be determined that the liquid delivery rate is decreasing overall in the second double plunger pump 7. Therefore, since the control unit 16 has confirmed the pressure drop in all sections, it concludes that a failure of the second seal 12b of the second double plunger pump 7 is suspected (step S617).

[0075] If no section with abnormal pressure is confirmed in steps S610 and S611, it is determined that there is no fault, and this flow chart is terminated (step S604).

[0076] In the above-described first embodiment, it is possible to determine whether the first double plunger pump 6 or the second double plunger pump 7 has a malfunction based on the change in the retention time of the internal standard substance.

[0077] In the above-described first embodiment, it is possible to identify the location of the failure in the consumables (first seal 11a, second seal 12a, first check valve 13a, second check valve 14a, first seal 11b, second seal 12b, first check valve 13b, second check valve 14b) from the section where the pressure abnormality is occurring.

[0078] <Method to estimate which consumable is faulty among multiple consumables in a plunger pump> As described above, the method for estimating a faulty consumable from among a plurality of consumables in the plunger pump in the liquid chromatograph of the first embodiment (the method for estimating a faulty part) is as follows: Discharging the solvent into the flow path 101 by the first double plunger pump 6 and the second double plunger pump 7; Introducing the sample 1 into the flow channel 101 via the dispensing unit 2 (step S601); Detecting the pressure of the solvent discharged by the first double plunger pump 6 and the second double plunger pump 7 (step S601); Separating the sample 1 into components using a separation column 3 (step S601); Detecting each component separated in the separation column 3 by the detection unit 4 (step S601); The method includes estimating a faulty consumable among the multiple consumables based on a first pressure detected in a first section (section g) in which the first plunger pump 9a (or 9b) discharges the solvent into the flow path, and a second pressure detected in a second section (section f) in which the second plunger pump 10a (or 10b) discharges the solvent into the flow path (steps S610 to S617).

[0079] The fault location estimation method is as follows: When detecting the components of the sample 1, a retention time of the internal standard substance supplied to the flow path 101 is acquired, and the retention time is compared with a predetermined value to determine whether it is ahead or behind (step S607); The method further includes estimating a faulty double plunger pump among the multiple double plunger pumps (the first double plunger pump 6 and the second double plunger pump 7) based on the determination result of the retention time, the type of the separation column 3 (reverse phase column, normal phase column), and the type of the solvent (water, methanol) (steps S607 to S609).

[0080] It is possible to estimate the defective consumables mentioned above. If the first pressure is not abnormal and the second pressure is abnormal, it is assumed that the second check valve is broken (steps S612 and S616). If the first pressure is abnormal and the second pressure is not abnormal, it is assumed that the first seal or the first check valve is faulty (steps S613 and S615). When the first pressure and the second pressure are abnormal, it is assumed that the second seal has failed (steps S614 and S617).

[0081] <Method for estimating which plunger pump is faulty among multiple plunger pumps> As described above, the method for estimating a faulty plunger pump from among a plurality of plunger pumps in the liquid chromatograph of the first embodiment (the method for estimating a faulty part) is as follows: Mixing multiple types of solvents using multiple double plunger pumps (6, 7) and discharging the mixed solvent into the flow path 101 (step S601); Introducing the sample 1 into the flow channel 101 via the dispensing unit 2 (step S601); Separating the sample 1 into components using a separation column 3 (step S601); Detecting each component separated in the separation column 3 by the detection unit 4 (step S601); When detecting the components of the sample 1, a retention time of the internal standard substance supplied to the flow path 101 is acquired, and the retention time is compared with a predetermined value to determine whether it is ahead or behind (step S607); and estimating a faulty plunger pump among the plurality of double plunger pumps (6, 7) based on the determination result of the retention time.

[0082] The above-mentioned faulty plunger pump can be estimated as follows: The method includes estimating which plunger pump among a plurality of double plunger pumps (6, 7) is faulty based on the determination result of the retention time, the type of the separation column 3 (reverse phase column, normal phase column), and the type of the solvent (water, methanol).

[0083] When the type of separation column to be used is determined, it is not necessary to provide the above-mentioned information on the type of separation column 3. When the type of solvent to be used is determined, it is not necessary to provide the above-mentioned information on the type of solvent.

[0084] Example 2 In the first embodiment, a liquid chromatograph having a high-pressure gradient liquid delivery function as shown in Fig. 1 is taken as an example. However, the present invention is also applicable to liquid chromatographs that do not have a high-pressure gradient liquid delivery function.

[0085] For example, a liquid chromatograph 900 configured with one double plunger pump 906 as shown in Fig. 9 will be described. This configuration has only one double plunger pump 906, and delivers only a solvent that has been prepared in advance. The liquid chromatograph 900 of Example 2 includes a dispensing unit 902 for introducing a sample 901 into the liquid chromatograph 900, a separation column 903, a detection unit 904, a waste liquid container 905, the double plunger pump 906, and a control unit 916.

[0086] Further, double plunger pump 906 has a pressure sensor 908, a first plunger pump 909, a second plunger pump 910, a first seal 911, a second seal 912, a first check valve 913, a second check valve 914, and a solvent bottle 915. The details of each part of double plunger pump 906 are similar to those in the first embodiment, and therefore the description thereof will be omitted.

[0087] Fig. 10 is a flowchart for estimating a fault location of a liquid delivery pump in a liquid chromatograph of Example 2. The processing from step S1001 to step S1004 in Fig. 10 is similar to the processing from step S601 to step S604 in Fig. 6 of Example 1, and therefore the description thereof will be omitted.

[0088] In the second embodiment, the control unit 916 checks for an abnormality in the liquid delivery pressure (step S1005). If the liquid delivery pressure is pulsating or is lower than usual (step S1005: YES), it is determined that there is a pressure abnormality and the process of step S1007 is executed.

[0089] On the other hand, if the control unit 916 determines that the measurement result of the internal standard is not abnormal (step S1005: NO), it suspects a malfunction other than that of the liquid delivery pump (step S1006) and ends this flowchart (step S1004).

[0090] The control unit 16 checks the value of the pressure sensor 908 of the double plunger pump 906, and checks the section where the pressure is abnormal (step S1007).

[0091] If it is confirmed that the pressure drops in sections b and c and that the pressure rises in sections d and e, it can be determined that the amount of liquid sent by the second plunger pump 910 has decreased and the amount of liquid sent by the first plunger pump 909 is normal. Therefore, since the control unit 16 has confirmed the pressure drop in sections b and c, it concludes that a malfunction of the second check valve 914 is suspected (step S1008).

[0092] Furthermore, if it can be confirmed that the pressure rises in sections b and c and drops in sections d and e, it can be determined that the amount of liquid sent by first plunger pump 909 has decreased and the amount of liquid sent by second plunger pump 910 is normal. Therefore, since the control unit 16 has confirmed the pressure drop in sections d and e, it concludes that a failure of first seal 911 or first check valve 913 is suspected (step S1009).

[0093] Moreover, if it is confirmed that the pressure is dropping in all sections, it can be determined that the liquid delivery rate is decreasing overall in the double plunger pump 906. Therefore, since the control unit 16 has confirmed the pressure drop in all sections, it concludes that a failure of the second seal 912 of the double plunger pump 906 is suspected (step S1010).

[0094] (Modification) The present invention is not limited to the above-mentioned embodiment, but includes various modified examples. The above-mentioned embodiment has been described in detail to clearly explain the present invention, and is not necessarily limited to those having all of the configurations described. It is also possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

[0095] In the first embodiment, the retention time is used as a feature amount of the measurement result of the internal standard to judge whether or not the multiple double plunger pumps (6, 7) are abnormal. In the first embodiment, it is possible to change the value used for the judgment according to the measurement content to be performed. Specifically, instead of the retention time of the internal standard, the half-width, peak height, peak symmetry, etc. of the internal standard may be used to judge whether or not the double plunger pumps (6, 7) are abnormal. In addition, the specified range to be compared with the feature amount (half-width, peak height, peak symmetry, etc.) of the internal standard is actually determined according to the purpose of the device user.

[0096] It is also possible to use a standard substance for the sole purpose of inspecting the normality of a liquid chromatograph, even if there is no measurement purpose. For example, a known standard substance for which normal data has been obtained in advance can be measured for the purpose of inspecting the device, and the normality of the device and the location of a failure in the event of an abnormality can be identified from the measurement results.

[0097] It is also possible to prescribe the type and range of pressure abnormality in the control unit. For example, a state in which periodic (predetermined period) pressure fluctuation occurs at or above a predetermined pressure fluctuation value (e.g., 5 MPa) may be determined as a pressure abnormality (pressure pulsation abnormality), and a state in which the average pressure value for a predetermined period (e.g., several seconds) falls below a predetermined pressure average value (e.g., 10 MPa) may be determined as a pressure abnormality (minimum pressure value abnormality).

[0098] The above-mentioned predetermined fluctuation value is a pressure fluctuation value at which the analysis of the target substance becomes difficult. The analysis of the target substance includes calculation of the retention time, half-width, peak height, peak area, or peak symmetry in the chromatogram obtained by the detection result by the detection unit.

[0099] The pressure fluctuation value that makes it difficult to analyze the measurement target substance is a pressure fluctuation value at which the retention time, half width, peak height, peak area, or peak symmetry of the internal standard measured together with the measurement target substance exceeds the statistical distribution range of the liquid chromatograph in the normal state. This statistical distribution range in the normal state is a range calculated from the average value and standard deviation of the retention time, half width, peak height, peak area, and peak symmetry of the internal standard obtained when the liquid chromatograph is operating normally. For example, it is also possible to pre-obtain statistical data of the retention time, half width, peak height, and peak symmetry of the measurement result of the internal standard substance when the device is normal, and to determine the average value and standard deviation of each, thereby defining the statistical distribution range in the normal state. For example, it is also possible to define the case where the respective average values ​​are deviated from each other by more than three times the standard deviation as an abnormality of the device.

[0100] It is also possible to define a normal range for the measurement results of the internal standard based on statistical data when the device is operating normally, and define a pressure abnormality as a pressure fluctuation that deviates from the normal range. For example, if a periodic pressure fluctuation of 5 megapascals or more occurs and deviates from the normal range of the internal standard, the pressure abnormality can be defined as a periodic pressure fluctuation of 5 megapascals or more.

[0101] In addition, when the fault location is identified, the present invention also includes a case where the device is immediately stopped and the device user is notified of the fault location. For example, the liquid chromatograph has a display monitor (display unit 21) for the device user, and the display monitor can display the estimated fault location and notify the device user. [Explanation of symbols]

[0102] 1...sample, 2...dispensing section, 3...separation column, 4...detection section, 5...waste liquid container, 6...first double plunger pump, 7...second double plunger pump, 8a, 8b...pressure sensor, 9a, 9b...first plunger pump, 10a, 10b...second plunger pump, 11a, 11b...first seal, 12a, 12b...second seal, 13a, 13b...first check valve, 14a, 14b...second check valve, 15a, 15b...solvent bottle, 16...control section, 17...processor, 18...main memory section, 19...auxiliary memory section, 20...interface, 100...liquid chromatograph, 900...liquid chromatograph, 901...sample, 902...dispensing section, 903...separation column, 904: detection unit; 905: waste liquid container; 906: double plunger pump; 908: pressure sensor; 909: first plunger pump; 910: second plunger pump; 911: first seal; 912: second seal; 913: first check valve; 914: second check valve; 915: solvent bottle; 916: control unit

Claims

1. A failure location estimation method for estimating a failure location of a liquid chromatograph, comprising: discharging the solvent into the flow path using a double plunger pump including a first plunger pump, a second plunger pump disposed downstream of the first plunger pump, and a plurality of consumables related to discharging the solvent; introducing a sample into the flow path; detecting the pressure of the solvent discharged by the double plunger pump; Separating the sample into components using a separation column; detecting each component separated by the separation column; estimating a faulty consumable item among the plurality of consumable items based on a first pressure detected in a first section in which the first plunger pump discharges the solvent into the flow path and a second pressure detected in a second section in which the second plunger pump discharges the solvent into the flow path; discharging a solvent different from the solvent into the flow path by one or more double plunger pumps different from the double plunger pump; When detecting the components of the sample, acquiring a retention time of an internal standard substance supplied to the flow path, and comparing the retention time with a predetermined value to determine whether the retention time is ahead or behind; and and estimating a faulty double plunger pump among the plurality of double plunger pumps based on the determination result of the retention time, the type of the separation column, and the type of the solvent. A fault location estimation method characterized by:

2. A failure location estimation method for estimating a failure location of a liquid chromatograph, comprising: discharging the solvent into the flow path using a double plunger pump including a first plunger pump, a second plunger pump disposed downstream of the first plunger pump, and a plurality of consumables related to discharging the solvent; introducing a sample into the flow path; detecting the pressure of the solvent discharged by the double plunger pump; Separating the sample into components using a separation column; Detecting each component separated by the separation column; and and estimating a faulty consumable item among the plurality of consumable items based on a first pressure detected in a first section in which the first plunger pump discharges the solvent into the flow path and a second pressure detected in a second section in which the second plunger pump discharges the solvent into the flow path, the plurality of consumables include a first seal of the first plunger pump, a first check valve disposed upstream of the first plunger pump, a second check valve disposed downstream of the first plunger pump, and a second seal of the second plunger pump; estimating the faulty consumable item If the first pressure is not abnormal and the second pressure is abnormal, it is assumed that the second check valve has failed; When the first pressure is abnormal and the second pressure is not abnormal, it is assumed that the first seal or the first check valve has failed; and inferring that the second seal has failed when the first pressure and the second pressure are abnormal. A fault location estimation method characterized by:

3. The pressure abnormality is a state in which the fluctuation of the pressure value over a predetermined period of time exceeds a predetermined pressure fluctuation value, or a state in which the average pressure value over a predetermined period of time is equal to or less than a predetermined average pressure value.

3. The method for estimating a fault location according to claim 2.

4. The predetermined pressure fluctuation value is a pressure fluctuation value at which analysis of the measurement target substance becomes difficult.

4. The method for estimating a fault location according to claim 3.

5. The analysis of the target substance includes calculating the retention time, half-width, peak height, peak area, or peak symmetry in the chromatogram obtained by the detection result of each component.

5. The method for estimating a fault location according to claim 4.

6. The pressure fluctuation value at which analysis of the target substance becomes difficult is a pressure fluctuation value at which the retention time, half-width, peak height, peak area, or peak symmetry of an internal standard substance measured together with the target substance exceeds the normal statistical distribution range of the liquid chromatograph.

5. The method for estimating a fault location according to claim 4.

7. The statistical distribution range of the liquid chromatograph under normal conditions is a range calculated from the average values ​​and standard deviations of the retention time, half-width, peak height, peak area, and peak symmetry of the internal standard obtained when the liquid chromatograph is operating normally.

7. The method for estimating a fault location according to claim 6.

8. a double plunger pump including a first plunger pump, a second plunger pump disposed downstream of the first plunger pump, and a plurality of consumables related to the discharge of a solvent; a pressure sensor for detecting the pressure of the solvent discharged by the double plunger pump; a dispensing unit that introduces a sample into the flow channel; a separation column connected downstream of the dispensing unit to separate the sample into components; a detection unit for detecting each component separated by the separation column; a control unit that estimates a faulty consumable item among the plurality of consumable items based on a first pressure detected by the pressure sensor in a first section in which the first plunger pump discharges the solvent into the flow path and a second pressure detected by the pressure sensor in a second section in which the second plunger pump discharges the solvent into the flow path; one or more double plunger pumps that are different from the double plunger pump and that discharge a solvent different from the solvent into the flow path, The control unit acquires a retention time of an internal standard substance supplied to the flow path when detecting components of the sample, compares the retention time with a predetermined value, determines whether the retention time is ahead or behind, and estimates a faulty double plunger pump among the plurality of double plunger pumps based on the determination result of the retention time, the type of the separation column, and the type of the solvent. A liquid chromatograph characterized by:

9. a storage unit that stores a reference table including information on sections where pressure abnormalities have occurred and information on faulty consumables; The control unit estimates a faulty consumable item among the plurality of consumable items based on the first pressure, the second pressure, and the reference table.

9. The liquid chromatograph according to claim 8.

10. a double plunger pump including a first plunger pump, a second plunger pump disposed downstream of the first plunger pump, and a plurality of consumables related to the discharge of a solvent; a pressure sensor for detecting the pressure of the solvent discharged by the double plunger pump; a dispensing unit that introduces a sample into the flow channel; a separation column connected downstream of the dispensing unit to separate the sample into components; a detection unit for detecting each component separated by the separation column; a control unit that estimates a faulty consumable item among the plurality of consumable items based on a first pressure detected by the pressure sensor in a first section in which the first plunger pump discharges the solvent into the flow path and a second pressure detected by the pressure sensor in a second section in which the second plunger pump discharges the solvent into the flow path, the plurality of consumables include a first seal of the first plunger pump, a first check valve disposed upstream of the first plunger pump, a second check valve disposed downstream of the first plunger pump, and a second seal of the second plunger pump; The control unit If the first pressure is not abnormal and the second pressure is abnormal, it is assumed that the second check valve has failed; When the first pressure is abnormal and the second pressure is not abnormal, it is assumed that the first seal or the first check valve has failed; and inferring that the second seal has failed when the first pressure and the second pressure are abnormal. A liquid chromatograph characterized by:

11. The pressure abnormality is a state in which the fluctuation of the pressure value over a predetermined period of time exceeds a predetermined pressure fluctuation value, or a state in which the average pressure value over a predetermined period of time is equal to or less than a predetermined average pressure value.

11. The liquid chromatograph according to claim 10.

12. A display unit that displays information about the estimated defective consumable item is further provided.

9. The liquid chromatograph according to claim 8.

13. A failure location estimation method for estimating a failure location of a liquid chromatograph, comprising: Mixing multiple types of solvents using multiple plunger pumps and discharging the mixture into the flow path; introducing a sample into the flow path; Separating the sample into components using a separation column; detecting each component separated by the separation column; When detecting the components of the sample, acquiring a retention time of an internal standard substance supplied to the flow path, and comparing the retention time with a predetermined value to determine whether the retention time is ahead or behind; and and estimating a faulty plunger pump among the plurality of plunger pumps based on the determination result of the retention time. A fault location estimation method characterized by:

14. estimating the faulty plunger pump includes: and estimating a faulty plunger pump among the plurality of plunger pumps based on the determination result of the retention time, the type of the separation column, and the type of the solvent.

14. The method for estimating a fault location according to claim 13.

15. a plurality of plunger pumps that mix a plurality of types of solvents and discharge the mixed solvent into the flow path; a dispensing unit that introduces a sample into the flow channel; a separation column connected downstream of the dispensing unit to separate the sample into components; a detection unit for detecting each component separated by the separation column; and a control unit that, when detecting components of the sample, acquires a retention time of an internal standard substance supplied to the flow path, compares the retention time with a predetermined value to determine whether the retention time is ahead or behind, and estimates a faulty plunger pump among the plurality of plunger pumps based on the determination result of the retention time. A liquid chromatograph characterized by:

16. The control unit estimates which plunger pump among the plurality of plunger pumps is faulty based on the determination result of the retention time, the type of the separation column, and the type of the solvent.

16. The liquid chromatograph of claim 15.

17. a memory unit for storing a lookup table including information on whether the retention time of the internal standard substance is ahead of or behind a specified time range, and information on a malfunctioning plunger pump; The control unit estimates a faulty plunger pump among the plurality of plunger pumps based on the determination result of the retention time and the reference table.

16. The liquid chromatograph of claim 15.

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