JP4377900B2 - Liquid chromatograph - Google Patents

Description

  The present invention relates to a liquid chromatograph apparatus suitable for performing liquid feeding at a low flow rate.

  A plunger pump having two plungers is known as a liquid chromatograph pump. In such a plunger pump, two plungers are independently driven by a motor, and pulsation of the flow rate is reduced by cooperative driving of both plungers.

  In the example described in Japanese Patent Laid-Open No. 63-75375, the second plunger also makes one reciprocation while the first plunger makes one reciprocation. to correct. That is, the first plunger determines the flow rate, and the second plunger is used for correcting the pulsation of the first plunger.

JP-A-63-75375

  Usually, when operating a liquid chromatograph pump, first, an eluent is filled in the pump and piping, and bubbles are exhausted. When the preparatory work is thus completed, the pump is then started, and when the discharge pressure reaches a predetermined target value, the operation is switched to the steady operation. After the steady operation, measurement by liquid chromatograph is started.

  A liquid chromatograph pump requires a low flow rate. For example, a very low flow rate of microliter (μl) and nanoliter (nl) levels per minute is required. In such a low flow rate or extremely low flow rate pump, it takes a long time from the start of the preparation work to the start of steady operation. In other words, the rise time at the start of the pump becomes longer.

  An object of the present invention is to provide a liquid chromatograph apparatus capable of shortening the rise time when the pump is started.

  The liquid chromatograph apparatus of the present invention has first and second pumps provided with plungers, a suction port and a discharge port, and the liquid sucked through the suction port passes through the first and second pumps. It discharges from the said discharge outlet. In the start-up operation mode, the second pump is stopped and only the first pump is operated. When the discharge pressure at the discharge port reaches a predetermined value, the startup operation mode is switched to the steady operation mode. In the steady operation mode, the first pump is stopped and only the second pump is operated.

  According to the present invention, it is possible to shorten the rise time when the pump is started.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1 and 2 show a liquid chromatograph apparatus according to the present invention. The liquid chromatograph apparatus of this example includes a liquid feeding system, an injector 53, a column 54, a detector 55, and a storage tank 56. The liquid feeding system of this example performs liquid feeding at an extremely low flow rate of, for example, 0.1 nL (nanoliter) / min to 50 μL (micronliter) / min to the column 54.

The liquid feeding system of this example has a storage tank 51 for storing an eluent or a solvent liquid, a degasser 14 for removing gas in the liquid, an active valve 5 having four ports, and two plungers. The plunger pump device 1 includes linear motion mechanisms (actuators) 122 and 222 connected to the plunger, motors 121 and 221 that drive the linear motion mechanism, and a controller 50 that controls the motors 121 and 221 and the active valve 5.
The active valve 5 is connected to the storage tank 51 via the deaeration device 14 and the suction pipe 15.

  The plunger pump device 1 is connected to the active valve 5 via a suction pipe 16, an intermediate discharge pipe 17, and an intermediate suction pipe 18, and is connected to an injector 53 via a discharge pipe 19. A drain valve 9 is provided in the discharge pipe 19.

  The plunger pump device 1 has first and second pressurizing chambers 102 and 202, and these pressurizing chambers are liquid-tight by seals 124 and 224. First and second plungers 101 and 201 are disposed in the first and second pressurizing chambers 102 and 103, respectively. The first and second plungers 101 and 201 are slidably held by bearings 123 and 223.

  A suction passage 103 and a discharge passage 104 are connected to the first pressurizing chamber 102. The suction passage 103 is connected to the suction pipe 16. A suction check valve 105 is provided in the suction passage 103. The discharge passage 104 is connected to the intermediate discharge pipe 17. A suction passage 203 and a discharge passage 204 are connected to the second pressurizing chamber 202. The suction passage 203 is connected to the intermediate suction pipe 18. The discharge passage 204 is connected to the discharge pipe 19. A pressure sensor 60 is provided in the discharge passage 204. The pressure in the discharge passage 204 detected by the pressure sensor 60 is herein referred to as the pump discharge pressure.

  Hereinafter, a portion including the first pressurizing chamber 102, the first plunger 101, the motor 121 for driving the first pressurizing chamber 102, and the linear motion mechanism 122 is referred to as a first pump, and the second pressurizing chamber 202, the second plunger 201, and A portion including the motor 221 to be driven and the linear motion mechanism 222 will be referred to as a second pump. As shown, the diameter of the first plunger 101 is larger than the diameter of the second plunger 201, and therefore the flow rate of the first pump is larger than the flow rate of the second pump.

  The active valve 5 is a rotary valve that switches a flow path by an external drive unit (not shown), and has four ports 5a, 5b, 5c, and 5d and two flow paths 5e and 5f. The volume of the flow paths 5e and 5f is very small. The first port 5a is connected to the suction pipe 15, the second port 5b is connected to the suction pipe 16, the third port 5c is connected to the intermediate discharge pipe 17, and the fourth port 5d is connected to the intermediate suction pipe 18. Yes.

  FIG. 1 shows a state in which the first and second ports 5a and 5b are connected by the flow path 5e, but the third and fourth ports 5c and 5d are not connected. FIG. 2 shows a state in which the third and fourth ports 5c and 5d are connected by the flow path 5f, but the first and second ports 5a and 5b are not connected.

  The rotations of the motors 121 and 221 are converted into linear motions by the linear motion mechanisms 122 and 222, respectively, and reciprocate the first and second plungers 101 and 201, respectively. The controller 50 provides a drive signal to the motors 121 and 221 based on a signal from the pressure sensor 60 and a valve open / close signal to the active valve 5.

  An outline of the liquid supply path in the liquid supply system of this example will be described. First, as shown in FIG. 1, when the first and second ports 5 a and 5 b are connected by the flow path 5 e, the solution in the storage tank 51 passes through the deaerator 14 and the suction pipe 15. Then, it is guided to the first port 5 a of the active valve 5, and is guided to the suction passage 103 of the plunger pump device 1 via the first flow path 5 e, the second port 5 b and the suction pipe 16. The solution is further guided to the first pressurizing chamber 102 via the suction check valve 105.

  On the other hand, when the third and fourth ports 5c and 5d are connected by the second flow path 5f as shown in FIG. 2, the solution in the first pressurizing chamber 102 is discharged from the discharge passage 104 and the intermediate discharge. It is guided to the third port 5 c of the active valve 5 through the pipe 17, and is guided to the suction passage 203 of the plunger pump device 1 through the second flow path 5 f, the fourth port 5 d and the intermediate suction pipe 18. The solution is further guided to the injector 53 via the second pressurizing chamber 202, the discharge passage 204, and the discharge pipe 19.

  A sample to be analyzed is injected by the injector 53. Thereby, the sample is mixed in the solution. The solution containing the sample is introduced into the column 54, and the components contained in the sample are separated from each other. Each separated component is analyzed by the detector 55. The column 54 is filled with fine silica gel particles, and a load pressure of about 10 MPa is generated in the plunger pump device 1 due to fluid resistance when flowing through the column 54. The magnitude of the load pressure varies depending on the diameter of the column and the passing flow rate.

  With reference to FIG. 3, operation | movement of the liquid feeding system of this example is demonstrated. At the same time, refer to FIGS. 3A shows the opening / closing operation of the drain valve, FIG. 3B shows the opening / closing operation of the active valve 5 with respect to the first plunger 101, FIG. 3C shows the displacement of the first plunger 101, and FIG. 3D shows the operation of the active valve 5 with respect to the second plunger 201. FIG. 3E shows the displacement of the second plunger 201, FIG. 3F shows the first pump flow rate, FIG. 3G shows the second pump flow rate, and FIG. 3H shows the pump discharge pressure detected by the pressure sensor 60. The horizontal axis is time.

  Further, as in the example of FIG. 1, in the active valve 5, the first and second ports 5a and 5b are connected by the flow path 5e, and the third and fourth ports 5c and 5d are not connected. Is called “open” for the first plunger 101 and “closed” for the second plunger 201. At this time, the first pressurizing chamber 102 is connected to the solution in the storage tank 51 through the active valve 5, but is not connected to the second pressurizing chamber 202.

  As shown in FIG. 2, a state where the third and fourth ports 5 c and 5 d are connected by the flow path 5 f and the first and second ports 5 a and 5 b are not connected to the first plunger 101. This is referred to as “closed” and is referred to as “open” with respect to the second plunger 201. At this time, the first pressurizing chamber 102 is connected to the second pressurizing chamber 202 via the active valve 5, but is not connected to the solution in the storage tank 51. The active valve 5 is “closed” with respect to the second plunger 201 when it is “open” with respect to the first plunger 101. Conversely, when the first plunger 101 is “closed”, the second plunger 201 is “open”.

  Further, the first and second plungers 101 and 201 are arranged at the left end of the pressurizing chamber when they are retracted by the motors 121 and 221 and the linear motion mechanisms 122 and 222, that is, in FIGS. The state in which the pressure is applied is said to be at the bottom dead center, and is in a state where it is pushed in by the motor 21 and the linear motion mechanism 22, that is, in the state disposed at the right end of the pressurizing chamber in FIGS. Is said to be at top dead center.

  In this example, the first pump and the second pump are used in the eluent filling and bubble discharging mode before the start of the test, the first pump is used in the start-up operation mode, and an extremely low flow rate is supplied in the steady operation mode. When performing, the second pump is used.

  First, the bubble discharge and eluent filling mode will be described. In the bubble discharge and eluent filling mode, bubbles in the pump, passage, and pipe included in the liquid feeding system of this example are discharged to fill the eluent. As shown in FIG. 3A, the drain valve 9 is opened. Comparing FIG. 3B and FIG. 3D, the opening / closing operation of the active valve 5 with respect to the second plunger 201 is delayed by a half cycle with respect to the opening / closing operation with respect to the first plunger 101.

  Comparing FIG. 3C and FIG. 3E, the reciprocating motion of the second plunger 201 is delayed by a half cycle with respect to the reciprocating motion of the first plunger 101. When the first plunger 101 is pulled and moves from the top dead center to the bottom dead center, the second plunger 201 is pushed in and moves from the bottom dead center to the top dead center. That is, the suction process of the first pump is the discharge process of the second pump. Conversely, when the first plunger 101 is pushed in and moves from the bottom dead center to the top dead center, the second plunger 201 is pulled in and moves from the top dead center to the bottom dead center. That is, the discharge process of the first pump is the suction process of the second pump.

  Comparing FIG. 3F and FIG. 3G, when the first pump is a suction process, the second pump is a discharge process. Conversely, when the first pump is in the discharge process, the second pump is in the suction process.

  Comparing FIG. 3B to FIG. 3E, the operation of the first and second plungers 2 is delayed by a quarter cycle with respect to the opening / closing operation of the active valve 5. Accordingly, the opening / closing operation of the active valve 5 in FIG. 3B with respect to the first plunger 101, the reciprocating motion of the first plunger 101 in FIG. 3C, the opening / closing operation of the active valve 5 in FIG. 3D with respect to the second plunger 2, and the second operation in FIG. The reciprocating motion of the plunger 2 is delayed by a quarter period in order.

  For example, as shown in FIG. 3B, the active valve 5 changes from “closed” to “open” with respect to the first plunger 101. Next, as shown in FIG. 3C, the first plunger 101 changes from the top dead center to the bottom dead center, and the suction process of the first pump is performed with a delay of a quarter cycle. Next, the active valve 5 changes from “closed” to “open” with respect to the second plunger 2 as shown in FIG. Next, as shown in FIG. 3E, the second plunger 2 changes from the top dead center to the bottom dead center, and the suction process of the second pump is performed with a delay of a quarter cycle.

  As shown in FIG. 3B, the active valve 5 changes from “open” to “closed” with a half cycle delay with respect to the first plunger 101. Next, as shown in FIG. 3C, the first plunger 101 is changed from the bottom dead center to the top dead center with a quarter cycle delay, and the discharge process of the first pump is performed. Next, the active valve 5 changes from “open” to “closed” with respect to the second plunger 2 as shown in FIG. Next, as shown in FIG. 3E, the second plunger 2 changes from the bottom dead center to the top dead center with a quarter cycle delay, and the discharge process of the second pump is performed.

  As shown in FIG. 3H, the discharge pressure of the pump includes a fluctuation component of the first pump flow rate and the second pump flow rate, but is substantially constant.

  As shown in FIG. 3, in the bubble discharge and eluent filling mode, the first and second plungers are reciprocated a plurality of times. From the drain valve 9, the difference between the first pump flow rate and the second pump flow rate is discharged, and at the same time, the bubbles are also removed. In this example, since the upstream first pump has a large flow rate, bubbles accumulated in the downstream second pressurizing chamber 202 can be easily discharged. Thereby, the test preparation can be completed in a short time.

  When the bubble discharge and eluent filling mode ends, the first and second plungers and the active valve are arranged at the home positions described below.

  Next, an operation of shifting from the pump start operation to the steady operation will be described. The first and second plungers and the active valve are disposed at the home position. In the home position, the active valve 5 is “open” with respect to the first plunger 101 and “closed” with respect to the second plunger 201. The first and second plungers are disposed at the bottom dead center. Therefore, the first and second pressure chambers are filled with the eluent.

  Hereinafter, when the active valve 5 is “open” with respect to the first plunger 101, it is simply described that the active valve 5 is “open”. Therefore, the active valve 5 being “open” means that the first plunger 101 is “open” and the second plunger 201 is “closed” as shown in FIG. To do. When the active valve 5 is “closed” with respect to the first plunger 101, the active valve 5 is simply described as “closed”. Therefore, the active valve 5 being “closed” means that the first plunger 101 is “closed” and the second plunger 201 is “open” as shown in FIG. means.

  When in the home position, the active valve 5 is “open”. First, the drain valve 9 is closed as shown in FIG. 3A, and the active valve 5 is changed from “open” to “closed” as shown in FIGS. 3B and 3D. Therefore, as shown in FIG. 2, the first pressurizing chamber 102 is connected to the second pressurizing chamber 202 via the active valve 5. As shown in FIG. 3C, the first plunger 101 is moved from the bottom dead center toward the top dead center at a predetermined speed, and the discharge process of the first pump is performed. As can be seen from the gradient of the graph, the moving speed of the first plunger 101 in the start-up operation of the pump is smaller than that in the bubble discharge and eluent filling mode. As shown in FIG. 3E, since the second plunger 201 is disposed at the bottom dead center, the eluent discharged from the first pressurizing chamber 102 is guided to the second pressurizing chamber 202 via the active valve 5. From there, it is discharged to the discharge pipe 19. At this time, the second pump is not substantially operated. Therefore, as shown in FIG. 3F, the first pump flow rate is a predetermined value corresponding to the moving speed of the first plunger 101, but as shown in FIG. 3G, the second pump flow rate is zero.

  As shown in FIG. 3H, when the pump discharge pressure reaches the target pressure Pset, the operation is switched to the steady operation. The target pressure Pset is determined by the column diameter and the passage flow rate. When the discharge pressure of the pump reaches the target pressure Pset, the pressure sensor 60 notifies the controller 50 of that.

  The controller 50 transmits a command for the steady operation mode to the first and second pumps and the active valve 5. In the steady operation, the liquid feed flow rate is kept constant while the discharge pressure is kept at the target pressure Pset.

  In the steady operation, as shown in FIGS. 3B and 3D, the active valve 5 is changed from “closed” to “open”. Accordingly, as shown in FIG. 1, the second pressurizing chamber 202 is cut off from the first pressurizing chamber 102. As shown in FIG. 3C, the first plunger 101 stops. The first plunger 101 is disposed at a predetermined position between the bottom dead center and the top dead center. Next, as shown in FIG. 3E, the second plunger 201 is moved from the bottom dead center to the top dead center at a low speed. The discharge process of the second pump is executed at a low speed. As shown in FIG. 3F, the first pump flow rate becomes zero, and as shown in FIG. 3G, the second pump flow rate becomes the target flow rate Qset. In this example, by pushing the second plunger 201 at a constant low speed, the discharge pressure can be held at the target pressure Pset, and the liquid feed flow rate can be held at the target flow rate Qset.

  When the steady operation is performed in this way, the sample to be analyzed is injected by the injector 53, the mixed solution enters the column 54, and is separated into components, and then the components are analyzed by the detector 55.

  In this example, the start-up operation of the pump operates only the first pump, and in the steady operation, only the second pump is operated. By this operation method, the time to reach the target pressure, that is, the rise time when starting the pump can be shortened.

  Next, switching from start-up operation to steady operation will be described. In practice, due to the response time when switching the active valve 5 and the presence of the dead volume of the active valve 5, the pump pressure may overshoot the target pressure Pset, and the rise time may be longer. Therefore, next, we will explain the countermeasures.

  FIG. 4 explains another operation method of the liquid feeding system of this example, similarly to FIG. The discharge of bubbles and filling of the eluent are the same as in FIG.

  In this example, as in the example of FIG. 3, only the first pump is operated in the start-up operation of the pump. As shown in FIG. 4H, when the pump discharge pressure reaches a value (Pset−ΔPset) lower than the target pressure Pset by ΔPset, the operation is switched to the steady operation. When the steady operation is started, as shown in FIGS. 4B and 4D, the active valve 5 is changed from “closed” to “open”. As shown in FIG. 4C, the first plunger 101 stops. As shown in FIG. 4F, the first pump flow rate becomes zero, and as shown in FIG. 4G, the second pump flow rate becomes the target flow rate Qset. As shown in FIG. 4H, the discharge pressure of the pump increases and reaches the target pressure Pset.

  In this example, the overshoot with respect to the target pressure can be reduced by performing the operation switching time from the first plunger 101 to the second plunger 201 earlier by Δt compared to the operation method of FIG. Note that the gradient of the pump discharge pressure at the time Δt is smaller than the gradient of the pump discharge pressure during the start-up operation.

  In this example, the switching time of the plunger is adjusted in order to reduce overshoot, but other methods, for example, a method of reducing the feed speed of the first plunger 101 may be used. In this manner, adjusting the plunger switching time or reducing the feed speed of the first plunger 101 in order to reduce the overshoot is hereinafter referred to as pressure correction.

Next, the effect of this embodiment is demonstrated using FIG. 5 and FIG.
FIG. 5 shows the result of measuring the change in the discharge pressure of the pump when the pump is changed from the starting operation to the steady operation. A solid curve 501 in FIG. 5 indicates the pump discharge pressure when pressure correction is performed, and a broken curve indicates the pump discharge pressure when pressure correction is not performed.

  When pressure correction is not performed, the rise time of the pump becomes longer and the variation in rise time data becomes larger. On the other hand, when pressure correction is performed, the rise time of the pump is greatly shortened, and data variation in the rise time is almost eliminated. Although not shown in the figure, when pressure correction is not performed, the target pressure may not be reached depending on the target flow rate or target pressure of the second pump, but when pressure correction is performed, Such a phenomenon did not occur.

  With reference to FIG. 6, the flow rate relationship between the first pump and the second pump when pressure correction is performed by the first pump (operation of the first plunger) will be described. The set flow rate of the first pump (the value obtained by multiplying the cross-sectional area of the first plunger by the feed speed of the first plunger) is Q1, and the set flow rate of the second pump (the cross-sectional area of the second plunger is the feed speed of the first plunger). If the value obtained by multiplication is Q2, and the flow coefficient at that time is α, the following equation is obtained.

  Q1 = α ・ Q2 (Formula 1)

  FIG. 6 shows the relationship between the flow coefficient α and the rising characteristics of the pump. When the flow coefficient α is large, the rise time is shortened, but when it is too large, overshoot occurs. On the other hand, when α is small, the rise time becomes long, but no overshoot occurs. The flow coefficient α = 1 is when the set flow rate of the first pump is the same as the set flow rate of the second pump. When the flow coefficient α = 1, the pump pressure may not reach the target pressure. Accordingly, the flow coefficient α is at least greater than 1.

  There is an optimum value for the flow coefficient α. The optimum value of the flow coefficient α varies depending on the target pressure and the target flow rate. In other words, if the target pressure and the target flow rate are determined, the optimum value of the flow coefficient α can be obtained. For example, when analyzing by a liquid chromatograph using the present liquid feeding system, a map of the target pressure with respect to the target flow rate may be created in advance. It is also possible to automatically start up the liquid feeding system of this example using this map. For example, the user inputs a target pressure. The liquid feeding system reads the target flow rate corresponding to the target pressure from the map, and obtains the optimum value of the flow coefficient α from the target flow rate. In this way, the liquid feeding system is operated with the optimum value of the flow coefficient α as the input value.

  In the example of FIGS. 1 and 2, the diameter of the first plunger is configured to be larger than the diameter of the second plunger. However, the first plunger diameter is the same as the second plunger diameter, and the moving speed of the first plunger is the same. May be larger than the moving speed of the second plunger. Thereby, the flow rate of the first pump becomes larger than the flow rate of the second pump.

  With reference to FIG. 7 thru | or FIG. 9, the other example of the liquid chromatograph apparatus of this invention is demonstrated. The same parts as those in the first example of the liquid chromatograph shown in FIGS. 1 to 3 are denoted by the same reference numerals, and the description thereof is omitted as appropriate. In this example, the active valve 5 has two ports 5c and 5d and one flow path 5f.

  The first port 5c of the active valve 5 is connected to the discharge passage 104 of the first pump, and the second port 5d is connected to the suction passage 203 of the second pump. The suction passage 103 of the first pump is connected to the storage tank 51 via the deaeration device 14 and the suction pipe 16. A discharge check valve 106 is provided in the discharge passage 104 of the first pump. Similar to the first example, the flow rate of the first pump is larger than the flow rate of the second pump.

  FIG. 7 shows a state where the first and second ports 5c and 5d of the active valve 5 are connected by a flow path 5f. Here, this state is referred to as the active valve 5 being “open”. FIG. 8 shows a state where the first and second ports 5c and 5d of the active valve 5 are not connected. Here, this state is referred to as the active valve 5 being “closed”.

  With reference to FIG. 9, the operation method of the liquid feeding system of this example is demonstrated. First, the bubble discharge and eluent filling mode will be described. As shown in FIG. 9A, the drain valve 9 is opened, and the active valve 5 is opened as shown in FIG. 9B. As shown in FIG. 9C, the first plunger 101 is reciprocated at a high speed. At this time, as shown to FIG. 9D, the 2nd plunger is arrange | positioned at the bottom dead center. As shown in FIG. 9E, liquid is fed by the upstream first pump having a large flow rate, and bubbles in the first and second pumps are discharged to fill the eluent. The flow rate of the second pump on the downstream side where the flow rate is small is zero. As shown in FIG. 9G, the discharge pressure of the pump is zero.

  In this example, the bubbles are discharged and the eluent filling mode is performed by the first upstream pump having a large capacity, so that the bubbles accumulated in the downstream second pressurizing chamber can be easily discharged. Thereby, the test preparation can be completed in a shorter time. As shown in FIG. 9E, the flow rate from the pump is intermittent, but there is no problem because the flow rate pulsation in this mode has no effect on the measurement accuracy.

  Next, switching from start-up operation to steady operation will be described. In the starting operation of the pump, as shown in FIG. 9A, the drain valve 9 is “closed”, and the active valve 5 is held in the “open” state as shown in FIG. 9B. As shown in FIG. 9C, the first plunger 101 is moved from the bottom dead center toward the top dead center at a predetermined speed. At this time, as shown to FIG. 9D, the 2nd plunger is arrange | positioned at the bottom dead center. As shown in FIG. 9E, the flow rate of the first pump becomes a predetermined value corresponding to the moving speed of the first plunger 101. As shown in FIG. 9F, the flow rate of the second pump is zero. As shown in FIG. 9G, the discharge pressure of the pump increases. When the pump discharge pressure reaches the target pressure Pset, the operation is switched to the steady operation. In this example, when the position of the first plunger 101 becomes Xini, the discharge pressure of the pump reaches the target pressure Pset.

  In the steady operation, the active valve 5 is “closed” as shown in FIG. 9B. The position of the first plunger 101 is held at Xini as shown in FIG. 9C, and the second plunger 201 is pushed into the second pressurizing chamber 202 at a low speed as shown in FIG. 9D. At this time, the flow rate of the first pump is zero as shown in FIG. 9E, and the flow rate of the second pump becomes the target flow rate Q1 as shown in FIG. 9F.

  As described above, according to the liquid feeding system of this example, the discharge of bubbles and the filling of the eluent can be performed in a short time, and the number of times of switching of the active valve can be reduced, which has the effect of improving the durability of the active valve. is there.

  FIG. 10 shows an example of a high pressure gradient operation system. The high-pressure gradient operation system connects two liquid feeding systems and performs high-pressure gradient operation. The high pressure gradient operation system of this example includes two liquid feeding systems 10 a and 10 b, a main controller 70, and a mixer 62. The first pressure sensors 60a and 60b are respectively provided in the discharge passages of the first pumps of the two liquid feeding systems 10a and 10b, and the second pressure sensors 61a and 61b are respectively provided in the first pressurizing chamber. Yes. The two liquid delivery systems 10a and 10b may be the same as the liquid delivery system in FIG. 1 except that the second pressure sensors 61a and 61b are provided. Each of the two liquid feeding systems 10a and 10b may be the above-mentioned other liquid feeding systems instead of the liquid feeding system shown in FIG.

  The discharge pipes 19 a and 19 b of the two liquid feeding systems 10 a and 10 b are connected to the mixer 62. The discharge side of the mixer 62 is connected to the injector 53.

  The gradient operation will be described with reference to FIG. The gradient operation means that the liquid is fed while the mixing ratio of the two types of eluents A and B is changed stepwise with time. That is, the ratio of the two liquid feeding flow rates Qa and Qb is changed while keeping the total liquid feeding flow rate (Qt = Qa + Qb) constant. As shown in FIG. 11A, the flow rate Qa of the first eluent A increases stepwise with time, for example, changes stepwise from Qa = 1 to 99. As shown in FIG. 11B, the flow rate Qb of the second eluent B decreases with time, and changes stepwise from Qb = 99 to 1, for example. As shown in FIG. 11C, the total liquid feeding flow rate Qt = Qa + Qb is constant, and its value is 100. The total liquid feeding flow rate Qt is the flow rate of the mixer 62. FIG. 11D shows the mixing ratio of the solution at the discharge point S of the mixer 62. The mixing ratio of the first eluent A and the second eluent B increases stepwise with time. For example, Qb / Qa = 1 to 99. In this example, the gradient is 100 steps. Accordingly, when the total liquid feeding flow rate Qt is 1 μL / min, the minimum flow rate and resolution are 1/100, that is, 10 nL / min.

  FIG. 11E shows the discharge pressure of the pump. The discharge pipes 19 a and 19 b of the two pumps are connected via a mixer 62. Neglecting the pressure drop or pressure loss due to the mixer 62, the discharge pressures of the two pumps are the same. That is, the discharge pressure detected by the first pressure sensor 60a of the first pump is equal to the discharge pressure detected by the second pressure sensor 60b of the second pump. Furthermore, the discharge pressure detected by these pressure sensors 60 a and 60 b is equal to the discharge pressure of the mixer 62.

  As shown in FIG. 11C, even if the total liquid feeding flow rate Qt is constant, as shown in FIG. 11E, the discharge pressure of the pump changes by a maximum of about 1.5 to 2 times. This is because when the mixing ratio of the two eluents changes, the fluid resistance when passing through the column changes. If the pump discharge pressure is kept constant, the total liquid supply flow rate Qt is not constant.

  On the other hand, the relationship between the mixing ratio and the pressure fluctuation is known from past experimental data. Therefore, the pressure fluctuation curve when the total liquid feeding flow rate Qt is constant can be predicted. Therefore, the discharge pressure of the mixer 62 may be measured, compared with the predicted value of the pressure fluctuation curve, and the pump may be driven using the difference between the two as a feedback signal.

  The solid curve in FIG. 11E is a measured value of the pump discharge pressure, and the broken curve is a target pressure obtained from past experimental data.

  As shown in FIG. 10, the output of the first pressure sensor 60 a provided in the pump of the first liquid delivery system is fed back to the main controller 70. The main controller 70 compares the measured value from the first pressure sensor 60a with the target pressure, and obtains the deviation between them. This deviation is transmitted to the controllers 50a and 50b of each pump. The controllers 50a and 50b control each pump based on the deviation.

  When the pump discharge pressure is lower than the target pressure, the total liquid supply flow rate (Qt = Qa + Qb) decreases. Therefore, the total liquid supply flow rate may be increased. However, it is unclear which of the two liquid feeding flow rates Qa and Qb is greatly reduced. For example, when it is actually determined that the second liquid supply flow rate Qb is decreasing while the first liquid supply flow rate Qa is decreasing, and the second liquid supply flow rate Qb is increased, The accuracy of the mixing ratio deteriorates. This is a problem called mutual interference in gradient operation.

In this example, it is assumed that the two liquid feeding flow rates Qa and Qb increase or decrease at the same rate. Therefore, as shown in FIG. 11F, a feedback gain proportional to the flow rate ratio is given to the two liquid feeding flow rates Qa and Qb. That is, proportional control is performed. For example, when the ratio Qa: Qb of the two liquid flow rates is 20:80, the feedback gains of the two liquid flow rates Qa and Qb are given by (20/100) × K and (80/100) × K, respectively. . K is a constant. If the total liquid flow rate Qt is insufficient by 5, the command values for the two pumps are given by 20+ (20/100) × K × 5 and 80+ (80/100) × K × 5, respectively. For example, if K is 1, the former is 21 and the latter is 84. According to this method, a reduction in the accuracy of the mixing ratio due to the difference between the two pumps is inevitable, but mutual interference can be avoided.
As described above, a high-pressure gradient system excellent in liquid feeding stability and mixing accuracy can be provided.

  FIG. 12A shows an example in which the liquid chromatograph apparatus of the present invention and a mass spectrometer system are combined. The liquid chromatograph apparatus includes a liquid feeding system 52, an injector 53, a column 54, and a high voltage spray (atomizer) 56. In this example, an electrospray ionization (ESI) method used for analyzing highly polar substances such as proteins and peptides is used as an interface for connecting the liquid chromatograph apparatus and the mass spectrometer 58. In the electrospray ionization method, when a sample solution is fed into a capillary to which a high voltage of 3 to 5 kV is applied, a very fine spray (spray) is generated under atmospheric pressure, and sample molecules are ionized. Thus, ionized sample molecules are introduced into the mass spectrometer. The mass spectrometer analyzes the value obtained by dividing the mass by the electric charge, and specifies the molecular weight.

  FIG. 12B and FIG. 12C show an example of processing data in the mass spectrometer. The mass spectrum of FIG.12 (b) and the mass chromatogram of FIG.12 (c) are shown.

  In proteome analysis, proteins are extracted from the collected cells and analyzed. However, the amount of proteins contained in the cells is extremely small, and proliferation is impossible. Therefore, in order to increase the detection sensitivity of the liquid chromatograph and mass spectrometer system, it is necessary to reduce the flow rate in the liquid chromatograph. In addition, the analysis time takes several hours to input the sample and process the data.

  By introducing the liquid feeding system of the present invention into the liquid chromatograph apparatus and the mass spectrometer system described above, the amount of the analytical sample put into the liquid chromatograph can be reduced to a small amount. Further, in the liquid feeding system of the present invention, since the rise time at the start of the pump is short, a long analysis time can be secured. As a result, the number of data processing cases can be increased.

  Further, the pressure of the pump may be monitored, and when a predetermined value (for example, the target pressure described above) is reached, a sample may be input and analysis may be started. Thereby, power saving can be achieved.

  FIG. 13 shows another example of the liquid chromatograph apparatus of the present invention. The same parts as those in the liquid chromatograph apparatus shown in FIG. The feature of this example is that the first pump 1 and the second pump 2 are configured as separate pumps. The liquid feeding system of this example includes two storage tanks 51-1 and 51-2, two deaeration devices (degassers) 14-1 and 14-2, two plunger pump devices 1 and 2, and a linear motion mechanism (actuator) ) 122, 222, motors 121, 221 for driving the linear motion mechanism, and a controller 50.

  The two plunger pump devices 1 and 2 are connected to the injector 53 via the discharge pipe 19. The discharge pipe 19 is provided with a drain valve 9 and a pressure sensor 60.

  The two plunger pump devices 1 and 2 correspond to the first and second pumps, respectively. Similar to the first example, the flow rate of the first pump is larger than the flow rate of the second pump.

  The first and second plunger pump devices 1 and 2 have first and second pressurizing chambers 102 and 202, respectively, and these pressurizing chambers are liquid-tight by seals 124 and 224. First and second plungers 101 and 201 are disposed in the first and second pressurizing chambers 102 and 202, respectively. The first and second plungers 101 and 201 are slidably held by bearings 123 and 223.

  A suction passage 103 and a discharge passage 104 are connected to the first pressurizing chamber 102. The suction passage 103 is connected to the storage tank 51-1 via the suction pipe 16-1 and the deaeration device 14-1. A suction check valve 105 is provided in the suction passage 103. The discharge passage 104 is connected to the discharge pipe 19. A discharge check valve 106 is provided in the discharge passage 104.

  A suction passage 203 and a discharge passage 204 are connected to the second pressurizing chamber 202. The suction passage 203 is connected to the storage tank 51-2 via a suction pipe 16-2 and a deaeration device 14-2. A suction check valve 205 is provided in the suction passage 203. The discharge passage 204 is connected to the discharge pipe 19. A discharge check valve 206 is provided in the discharge passage 204.

  Next, the pump operation of the liquid feeding system will be described. In the bubble discharge and eluent filling mode, the drain valve 9 is opened, the two plunger pump devices are operated, and the bubbles in the pressurizing chamber and the passage are discharged, respectively. In the starting operation, the drain valve 9 is closed and only the first plunger 101 is operated. The flow rate of the first plunger 101 is larger than the flow rate of the second plunger 201. Therefore, the discharge pressure of the pump easily reaches the target pressure. When the discharge pressure of the pump reaches the target pressure, the start operation of the pump is changed to the steady operation. In steady operation, the drain valve 9 is closed, the first plunger pump device is stopped, and only the second plunger pump device is operated. The second plunger is pushed into the second pressurizing chamber 202 at a low speed. Thereby, a predetermined pump flow rate can be achieved while maintaining the discharge pressure of the pump at the target pressure.

  In this embodiment, a discharge check valve is provided on the discharge side of the pump, but the above-described active valve may be used.

  In the liquid feeding system of this example, two pumps are provided as separate elements, and both are connected by piping. Therefore, the work for disassembling the pump is facilitated, and maintenance work such as seal replacement is facilitated. In addition, advantages such as improved device layout can be obtained.

It is a figure which shows schematic structure of the 1st example of the liquid chromatograph apparatus of this invention, and shows the state which an active valve is "open" with respect to a 1st plunger, and is "closed" with respect to a 2nd plunger. It is a figure which shows schematic structure of the 1st example of the liquid chromatograph apparatus of this invention, and shows the state which an active valve is "closed" with respect to a 2nd plunger, and is "open" with respect to a 2nd plunger. It is a figure which shows an example of the drive method of the 1st example of the liquid chromatograph apparatus of this invention. It is a figure which shows the other example of the drive method of the 1st example of the liquid chromatograph apparatus of this invention. It is a figure which shows the experimental result of the pressure characteristic of the pump of this invention. It is a figure which shows the experimental result of the pressure characteristic of the pump of this invention. It is a figure which shows schematic structure of the 2nd example of the liquid chromatograph apparatus of this invention, and shows the state which an active valve is "open". It is a figure which shows schematic structure of the 2nd example of the liquid chromatograph apparatus of this invention, and shows the state which an active valve is "closed." It is a figure which shows an example of the drive method of the 2nd example of the liquid chromatograph apparatus of this invention. It is a figure which shows the example of the high voltage | pressure gradient driving | operation system of this invention. It is a figure which shows an example of the drive method of the high voltage | pressure gradient driving | operation system of this invention. FIG. 12A is a diagram showing an example of a liquid chromatograph apparatus and a mass spectrometer system of the present invention. FIG. 12B and FIG. 12C are diagrams showing the results of analysis by a mass spectrometer. It is a figure which shows schematic structure of the 3rd example of the liquid chromatograph apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Plunger pump apparatus, 5 ... Active valve, 5a, 5b, 5c ... Port, 5e, 5f ... Flow path, 9 ... Drain valve, 10 ... Plunger pump apparatus, 14, 14 '... Deaerator (degasser), 15 , 16 ... Suction pipe, 17 ... Discharge pipe, 18 ... Suction pipe, 19 ... Discharge pipe, 20 ... Plunger pump device, 50, 50a, 50b ... Controller, 51a, 51b ... Eluent, 53 ... Injector, 54 ... Column, 55 ... Detector, 56 ... Spray, 58 ... Mass spectrometer, 60, 60a, 60b, 61a, 61b ... Pressure sensor, 62 ... Mixer, 70 ... Main controller, 101 ... First plunger, 102 ... First pressurizing chamber , 103 ... Suction passage, 104 ... Discharge passage, 105 ... Suction check valve, 106 ... Discharge check valve, 121 ... Motor, 122 ... Direct acting mechanism DESCRIPTION OF SYMBOLS 123 ... Bearing, 124 ... Seal, 201 ... 2nd plunger, 202 ... 2nd pressurization chamber, 203 ... Suction passage, 204 ... Discharge passage, 205 ... Suction check valve, 206 ... Discharge check valve, 221 ... Motor, 222 ... Linear motion mechanism, 223 ... Bearing, 224 ... Seal

Claims (3)

A first liquid feeding device that sucks the first solution from the first suction pipe and discharges the first solution to the first discharge pipe, and a second liquid that sucks the second solution from the second suction pipe and discharges it to the second discharge pipe. And the first discharge pipe and the second discharge pipe are connected and discharged to the third discharge pipe while the mixing ratio of the first and second solutions is changed stepwise with time. In a liquid chromatograph apparatus for analyzing a sample with a detector after being introduced into the column and separated by the column,
The first liquid delivery device is disposed between the first suction pipe and the first discharge pipe, and is respectively supplied to a first pump and a second pump driven by a motor, and to the first discharge pipe. A first pressure sensor for detecting a discharge pressure of the first solution to be discharged;
A first position for connecting the first suction pipe to the first pump and blocking between the first pump and the second pump; and a path between the first suction pipe and the first pump. A first active valve movable between a second position connecting between the first pump and the second pump;
With
The second liquid delivery device is disposed between the second suction pipe and the second discharge pipe, and is respectively driven by a motor to a third pump and a fourth pump, and to the second discharge pipe. A second pressure sensor for detecting a discharge pressure of the second solution to be discharged;
A first position for connecting the second suction pipe to the third pump and blocking between the third pump and the fourth pump; and a path between the second suction pipe and the third pump. A second active valve movable between a second position connecting between the third pump and the fourth pump;
With
A liquid chromatograph that performs a gradient operation that gives a feedback gain proportional to a ratio of two liquid feeding flow rates to a signal for controlling the liquid feeding flow rates of the first and second liquid feeding devices. apparatus. The liquid chromatograph apparatus according to claim 1,
In the first liquid delivery device, the first active valve is disposed at the second position, the second pump is stopped, only the first pump is operated, and the discharge pressure of the first solution is When the target pressure is reached, the first active valve is disposed at the first position, the first pump is stopped, and the steady operation is performed in which only the second pump is operated,
In the second liquid delivery device, the second active valve is disposed at the second position, the fourth pump is stopped, only the third pump is operated, and the discharge pressure of the second solution is When the target pressure is reached, the second active valve is arranged at the first position, the third pump is stopped, and the steady operation is performed in which only the fourth pump is operated. Graph device. The liquid chromatograph apparatus according to claim 1,
A pressure fluctuation curve indicating the relationship between the mixing ratio and the pressure fluctuation when the total liquid flow rate is constant is obtained in advance from past experimental data, and the first discharge pipe and the second discharge pipe are connected. The discharge pressure of the mixer is measured, and the discharge pressure is compared with the pressure fluctuation curve.
A liquid chromatograph apparatus characterized in that the first and second liquid feeding apparatuses are operated as feedback signals .

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