JP2006343271A - Autosampler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an autosampler not requiring a user to customize operation by a command, when performing cutoff operation of a sample loop, concerning the autosampler for injecting a sample by a whole quantity injection system. <P>SOLUTION: An injection time calculation means for calculating an injection time corresponding to the injection quantity of each sample based on the injection time per unit sample injection quantity set beforehand is provided, and a passage is switched so that the sample loop filled with the sample is inserted into a moving phase passage when starting sample injection. Then, the passage is switched so that the sample loop is separated from the moving phase passage at the point of time when the injection time has elapsed after start of the sample injection. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an automatic sample introduction device (autosampler) for introducing a sample into a liquid chromatograph.

  In an analysis using a liquid chromatograph, an autosampler is used to automatically introduce a plurality of samples into a column in a predetermined order. As such an autosampler, a sample employing a so-called total injection method in which a predetermined amount of sample is collected from a sample bottle and injected into a mobile phase flow channel is widely used (for example, patent documents). 1). In injecting a sample by the total amount injection method, first, a predetermined amount of sample is sucked from a sample bottle by a needle, and the sample is filled in a sample loop (metering loop) connected to the base of the needle. Subsequently, the needle was inserted into the sample injection port, and the other end of the sample loop and the sample injection port were connected to the pipe connected to the mobile phase container and the column by the flow path switching valve, respectively. Conducted to piping. As a result, the sample loop is inserted into the mobile phase flow path, and the sample filled in the sample loop is pushed out as the mobile phase passes through the sample loop, and the entire amount is introduced into the column. Is done.

  In liquid chromatographic analysis, so-called gradient analysis is often performed in which sample components are eluted while sequentially changing the mobile phase composition using a plurality of types of solvents. When such a gradient analysis is performed on a plurality of samples, each time the analysis for one sample is completed, the flow channel is initialized by replacing it with a mobile phase having the same composition as that at the start of the analysis. There is a need. Therefore, as the number of samples increases, the time loss due to the initialization of the mobile phase becomes a big problem.

  In order to shorten the time required for the initialization of the mobile phase as described above, it is desirable to reduce the capacity of the entire analysis system including the liquid chromatograph apparatus and the autosampler. However, the sample loop of the autosampler has a relatively large capacity in order to give versatility to sample measurement. For this reason, in the full-volume injection type autosampler as described above, if the gradient analysis is performed with the sample loop inserted in the mobile phase flow path, it takes a long time to return the mobile phase to the initial state. there were.

  Therefore, conventionally, when performing a gradient analysis using a full-volume injection type autosampler, the sample loop is disconnected from the mobile phase flow channel when the sample injection into the mobile phase flow channel is completed (this is called “cut” The operation of the autosampler has been customized as “off”.

JP 2003-215118 A

  However, such customization of the sample injection operation has to be performed using a BASIC program or a similar command. In this case, it is necessary to understand the operation contents defined for each command and the meaning of various numerical parameters (for example, the number of times, time, amount, etc.) associated with each command. It was difficult to do this. In addition, the time from the start of sample injection until the sample loop is cut off (in the present invention, this is referred to as “injection time”) has to be obtained manually by the user. Furthermore, even simple operation changes need to be programmed on a command basis, and if the sample injection volume or mobile phase flow rate changes, the program must be changed for optimization. It was a lot of work.

  Therefore, the problem to be solved by the present invention is that an autosampler that injects a sample by the full volume injection method does not require the user to customize the operation by a command when performing a cut-off operation of the sample loop. Is to provide.

The first aspect of the autosampler according to the present invention, which has been made to solve the above-mentioned problems, is by inserting a sample loop in a mobile phase flow path for sending a mobile phase to a liquid chromatograph, In an autosampler for injecting a sample filled in the sample loop into the mobile phase flow path,
a) channel switching means for switching between a state in which the sample loop is inserted in the mobile phase channel and a state in which the sample loop is disconnected from the mobile phase channel;
b) setting means for setting the injection time per predetermined sample injection amount;
c) an injection time calculating means for calculating an injection time corresponding to the injection amount of each sample based on the injection time per predetermined sample injection amount set by the setting means;
d) At the time of sample injection, the sample loop is inserted into the mobile phase flow path, and the flow path switching means is controlled so that the sample loop is disconnected from the mobile phase flow path after the injection time has elapsed from the start of sample injection. Control means;
It is characterized by having.

Further, the second aspect of the autosampler according to the present invention is the sample filled in the sample loop by inserting the sample loop in the mobile phase flow path for sending the mobile phase to the liquid chromatograph. In an autosampler for injecting into the mobile phase flow path,
a) channel switching means for switching between a state in which the sample loop is inserted in the mobile phase channel and a state in which the sample loop is disconnected from the mobile phase channel;
b) setting means for setting a liquid feeding multiple indicating how many times the volume of the injected sample is to be delivered after sample injection;
c) injection time calculation means for calculating the mobile phase flow rate at the time of sample injection and the injection time according to the injection amount of each sample, based on the liquid feeding multiple set by the setting means;
d) At the time of sample injection, the sample loop is inserted into the mobile phase flow path, and the flow path switching means is controlled so that the sample loop is disconnected from the mobile phase flow path after the injection time has elapsed from the start of sample injection. Control means;
It is characterized by having.

  Furthermore, it is desirable that the autosampler of the present invention is provided with a sample loop cleaning means for cleaning the sample loop.

  According to the first aspect of the autosampler according to the present invention, the injection amount of each sample is set based on a preset injection time per predetermined sample injection amount (for example, injection time per 1 μL of sample injection amount). The injection time corresponding to the value is automatically calculated, and the cut-off operation of the sample loop is executed at an appropriate timing. In addition, according to the second aspect of the autosampler according to the present invention, each sample is set based on a preset number of times of feeding that indicates how many times the volume of the injected sample is to be fed after sample injection. The injection time is automatically calculated according to the injection amount and the liquid flow rate of the mobile phase, and the sample loop cut-off operation is executed at an appropriate timing.

  Therefore, according to the autosampler of the present invention, when the sample loop is cut off, the user himself / herself customizes the operation program by the command, and a plurality of types of programs corresponding to the sample injection amount and the mobile phase flow rate are prepared. This saves time and simplifies the time for setting conditions and preparation. As a result, the burden on the user can be reduced and the time required for the entire analysis can be shortened.

  Furthermore, when the sample loop cleaning means is provided in the autosampler of the present invention, the sample loop remaining in the sample loop is mixed into the next sample by cleaning the sample loop each time the injection of each sample is completed. It is possible to prevent the occurrence of errors due to the operation.

  Hereinafter, the best mode for carrying out the present invention will be described based on examples.

  1 to 3 show a schematic configuration of a liquid chromatograph autosampler according to an embodiment of the present invention. This autosampler injects a sample by a full-volume injection method. FIG. 1 shows a flow path configuration when measuring a sample from a sample bottle, and FIG. 2 shows a flow when a measured sample is injected into a mobile phase flow path. FIG. 3 shows a state in which the sample loop is cut off after sample injection.

  The autosampler according to the present embodiment is roughly composed of an operation unit 100 that performs sample weighing and injection operations and a control unit 200 that controls the operation unit 100. The operating unit 100 is provided with a high pressure valve 11 having six ports and a low pressure valve 12 having five ports. These are rotary flow path switching valves, and the connection state between adjacent ports can be switched by a rotating operation.

  The port a of the high-pressure valve 11 is connected to a flow path connected to a liquid feed pump 13 for supplying a mobile phase, the port b is connected to one end of a sample loop 14, and the port c is further connected to a metering pump 15. However, the sample injection port 16 is connected to the port e, and the flow path to the column of the liquid chromatograph is connected to the port f. In addition, two mobile phase vessels 17 and 18 containing different types of solvents are connected to the liquid feed pump 13, and the opening degree of valves 19 and 20 provided in each mobile phase vessel 17 and 18 is adjusted. By doing so, the composition of the mobile phase fed by the liquid feed pump 13 can be changed.

  Further, the container 21 storing the cleaning liquid is connected to the port g of the low pressure valve 12, the needle cleaning port 22 is connected to the port i, the metering pump 15 is connected to the port j, and the port k is connected to the port d of the high pressure valve 11. Has been.

  A needle 23 for aspirating and injecting a sample is provided at the end of the sample loop 14, and the needle 23 can be moved in a horizontal direction and a vertical direction by a driving mechanism (not shown). Thereby, the needle 23 can be moved onto the sample bottle, the sample injection port 16 and the needle washing port 22 arranged in the sample rack 24 and inserted into them.

  Further, the operation unit 100 includes a container for storing a cleaning liquid for cleaning the outside of the needle 23, a liquid feed pump, and a cleaning port, in addition to the above-described channel for measuring and injecting the sample. A needle outer cleaning flow path 25 is provided.

  On the other hand, as shown in FIG. 4, the control unit 200 includes an input unit 31 having a keyboard and the like, and a display unit 32 having a monitor and the like, and analysis conditions input using the input unit 31. A storage unit 33 for storing the injection time, an injection time calculation unit 34 for calculating the injection time of each sample based on the information stored in the storage unit, the valves 11 and 12 of the operation unit 100, the needle drive mechanism, the metering pump 15 and the like. An operation control unit 35 that controls the operation and a central control unit 36 that controls these operations are provided. The central control unit 36, the storage unit 33, and the injection time calculation unit 34 can be configured by, for example, a personal computer equipped with a predetermined program, and the operation control unit 35 is a computer installed in the autosampler body. Or the like.

  In the autosampler of this embodiment, when the sample loop 14 is cut off after sample injection, the user uses the input unit 31 in advance to specify the sample number, injection order, injection amount for each sample, and the like. Is created, and the injection time per 1 μL of the sample injection volume is set and stored in the storage unit 33.

  Hereinafter, measurement and injection of the sample and cut-off of the sample loop by the autosampler of the present embodiment will be described with reference to the flowchart shown in FIG.

  First, when the user performs a predetermined operation with the input unit 31 to instruct the start of analysis, the high pressure valve 11 and the low pressure valve 12 are switched to the state shown in FIG. As a result, the high pressure valve 11 is in a position (load position) where the ports b and c, d and e, and f and a communicate with each other, and the liquid feed pump 13 and column, the sample loop 14 and the metering pump 15 are respectively connected to the high pressure valve 11. (S1).

  Subsequently, the needle 23 is inserted into a predetermined sample bottle on the sample rack 24 by the drive mechanism, and a predetermined amount of sample is sucked by the suction operation of the metering pump 15 and filled in the sample loop 14 (S2). When the measurement of the sample is completed, the needle 23 is inserted into the injection port 16, and the high pressure valve 11 and the low pressure valve 12 are switched to the state shown in FIG. As a result, the high pressure valve 11 is in a position (injection position) in which the ports a and b, c and d, and e and f communicate with each other (S3). As a result, the sample loop 14 is inserted between the flow path connected to the liquid feed pump 13 and the flow path leading to the column, and the sample filled in the sample loop 14 together with the mobile phase is injected into the injection port 16. (S4).

Subsequently, the injection time t per 1 μL of the sample injection amount and the injection amount i (μL) of the sample to be injected, which are set in advance by the user, are read from the storage unit 33, and the injection time T of the sample is determined as the injection time. By the calculation unit 34, the following formula:
T = i × t
(S5).

  When the injection time T obtained by the above equation has elapsed since the start of sample injection, the high-pressure valve 11 is switched to the load position again, and the sample loop 14 is cut from the mobile phase flow path as shown in FIG. It is turned off (S6). Thereafter, gradient analysis by liquid chromatography is performed while sequentially changing the composition of the mobile phase.

  After waiting until the analysis is completed (S7), initialization is performed by replacing the inside of the flow path with a mobile phase having the same composition as that at the start of analysis (S8). At this time, since the mobile phase composition in the sample loop 14 remains at the start of analysis, it is not necessary to perform initialization. When the initialization of the mobile phase is completed, it is determined whether or not the injection of all the samples has been completed (S9). If it has been completed, a series of operations is completed. If the injection of all the samples has not been completed, the process returns to S2 and the measurement of the next sample is started.

  As described above, according to the autosampler of this embodiment, even when the sample loop is cut off in the gradient analysis, the apparatus automatically calculates the injection time according to the injection amount of each sample, and at an appropriate timing. Perform sample loop cutoff. Therefore, it is not necessary for the user to obtain the injection time by manual calculation, and it is possible to save the trouble of customizing the operation by the command.

In the present embodiment, the injection time calculation unit 34 calculates the injection time according to the injection amount of each sample based on the injection time per 1 μL of the sample injection amount set in advance. A liquid feeding multiple a indicating how many times the volume of the injected sample is to be delivered after sample injection is set, and injection is performed according to the mobile phase flow rate r at the time of sample injection and the injection quantity i of each sample. Time T is expressed by the following equation:
T = a × i / r
It is good also as what is calculated from.

  A schematic configuration of an autosampler having a sample loop cleaning function according to the second embodiment of the present invention is shown in FIGS. Constituent elements common to the first embodiment are denoted by the same reference numerals, and description thereof is omitted as appropriate.

  The high-pressure valve 11 has six ports a to f, and can take a position (load position) for communicating adjacent ports as shown in FIG. 6 and a position (injection position) for communicating as shown in FIG. . A flow path connected to a liquid feed pump 13 for feeding a mobile phase is connected to port a, one end of a sample loop 14 is connected to port b, a sample injection port 16 is connected to port e, and port f is connected to port f Is connected to the flow path to the column of the liquid chromatograph. The port d is connected to the drain via the check valve 26.

  The low pressure valve 12 includes a common valve m provided at the center of rotation and six ports g to l provided around the common valve m, and the common port m is set to one of the other ports g to l by a rotating operation. In addition to the communication, the two adjacent ports among the ports g to l are selectively communicated with each other. The common port m and the port i are connected to the metering pump 15, the port g is a cleaning liquid container 21a containing the cleaning liquid A, the port h is a cleaning liquid container 21b containing the cleaning liquid B, and the port j is a high pressure valve 11. The needle washing port 22 is connected to the port c, the port k is connected to the needle washing port 22, and the mobile phase container 17 is connected to the port l.

  In the autosampler of this embodiment, each valve is in the state shown in FIG. 6, the sample loop 14 is connected to the metering pump 15 to suck the sample, and in the state shown in FIG. 14 is inserted into the mobile phase flow path, and the sample is injected into the injection port 16. Thereafter, when the injection time of the sample calculated by the injection time calculation means 34 has elapsed, the sample loop 14 is cut off by switching the high pressure valve 11 to the load position (FIG. 8).

  The sample weighing / injection operation and the sample loop cut-off operation are performed in substantially the same procedure as in the flowchart of FIG. 5, but in the autosampler of this embodiment, after the sample loop cut-off is completed, The following sample loop cleaning operation is executed between S6 and S7.

  In the sample loop cleaning operation, first, as shown in FIG. 9, the common port m of the low-pressure valve 12 and the port l connected to the mobile phase container 17 are communicated, and the suction pump of the metering pump 15 causes the syringe to enter the syringe. Aspirate the mobile phase. Subsequently, as shown in FIG. 10, the port i and the port j of the low-pressure valve 12 are communicated, and the mobile phase in the syringe is sent out by the discharge operation of the metering pump 15. As a result, the mobile phase is fed into the sample loop 14 and discharged to the drain via the injection port and the check valve 26. The mobile phase is repeatedly sucked and discharged as described above, and when the predetermined amount of liquid is delivered, the cleaning operation is terminated, and the steps after S7 are executed.

  Here, the case where only the mobile phase is used as the cleaning liquid for the sample loop has been described, but the cleaning liquids A and B may be used as necessary. In this case, it is desirable to first clean the sample loop using one or both of the cleaning liquids A and B, and then clean the sample loop using the mobile phase.

  As described above, according to the automatic sample injection device of the present embodiment, the sample loop is cleaned each time the sample is injected, so that an error caused by mixing the sample remaining in the sample loop into the next sample is eliminated. Therefore, more accurate analysis can be performed.

The schematic diagram which shows the flow-path structure at the time of sample measurement in the autosampler which concerns on 1st Example of this invention. Schematic which shows the flow-path structure at the time of sample injection in the autosampler of the Example. Schematic which shows the state by which the sample loop was cut off in the auto sampler of the Example. The block diagram which shows the structure of the control part of the auto sampler of the Example. The flowchart which shows the operation | movement procedure in the auto sampler of the Example. Schematic which shows the flow-path structure at the time of sample measurement in the autosampler which concerns on the 2nd Example of this invention. Schematic which shows the flow-path structure at the time of sample injection in the autosampler of the Example. Schematic which shows the state by which the sample loop was cut off in the auto sampler of the Example. Schematic which shows the flow-path structure at the time of attracting | sucking a washing | cleaning liquid in the autosampler of the Example. Schematic which shows the flow-path structure at the time of discharging a washing | cleaning liquid in the autosampler of the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Operation part 200 ... Control part 11 ... High pressure valve 12 ... Low pressure valve 13 ... Liquid feed pump 14 ... Sample loop 15 ... Metering pump 16 ... Sample injection port 17, 18 ... Mobile phase container 19, 20 ... Valve 21, 21a, 21b ... Cleaning liquid container 22 ... Needle cleaning port 23 ... Needle 24 ... Sample rack 25 ... Needle outer cleaning flow path 26 ... Check valve 31 ... Input unit 32 ... Display unit 33 ... Storage unit 34 ... Injection time calculation unit 35 ... Operation control Unit 36 Central control unit

Claims (3)

In an autosampler for injecting a sample filled in the sample loop into the mobile phase channel by inserting the sample loop in the mobile phase channel for sending the mobile phase to the liquid chromatograph,
a) channel switching means for switching between a state in which the sample loop is inserted in the mobile phase channel and a state in which the sample loop is disconnected from the mobile phase channel;
b) setting means for setting the injection time per predetermined sample injection amount;
c) an injection time calculating means for calculating an injection time corresponding to the injection amount of each sample based on the injection time per predetermined sample injection amount set by the setting means;
d) At the time of sample injection, the sample loop is inserted into the mobile phase flow path, and the flow path switching means is controlled so that the sample loop is disconnected from the mobile phase flow path after the injection time has elapsed from the start of sample injection. Control means;
An autosampler characterized by comprising: In an autosampler for injecting a sample filled in the sample loop into the mobile phase channel by inserting the sample loop in the mobile phase channel for sending the mobile phase to the liquid chromatograph,
a) channel switching means for switching between a state in which the sample loop is inserted in the mobile phase channel and a state in which the sample loop is disconnected from the mobile phase channel;
b) setting means for setting a liquid feeding multiple indicating how many times the volume of the injected sample is to be delivered after sample injection;
c) injection time calculation means for calculating the mobile phase flow rate at the time of sample injection and the injection time according to the injection amount of each sample, based on the liquid feeding multiple set by the setting means;
d) At the time of sample injection, the sample loop is inserted into the mobile phase flow path, and the flow path switching means is controlled so that the sample loop is disconnected from the mobile phase flow path after the injection time has elapsed from the start of sample injection. Control means;
An autosampler characterized by comprising: The autosampler according to claim 1 or 2, further comprising a sample loop cleaning means for cleaning the sample loop.

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