Abstract:
In the present invention, differences in liquid feed properties between liquid chromatographic devices are determined, a liquid feed time table that takes these differences into account is acquired by way of system changes, and flow control is performed by a pump. Furthermore, the liquid feed time table after the system changes is divided into a plurality of intervals, and instructions are sent to the pump after approximate calculations are performed. Thus, by efficiently performing system change processes, the same measurement results can be obtained in a plurality of different liquid chromatograph devices, regardless of the differences in liquid feed properties.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a liquid chromatograph and particularly relates to system conversion among a plurality of liquid chromatographs. 
       BACKGROUND ART 
       [0002]    An analytical technique using a liquid chromatograph needs to be highly accurate. A measuring method can be exemplified as contents to be set in the liquid chromatograph when a chromatogram is measured, and examples thereof include a flow rate, a sample injection amount, a temperature setting of a column oven, a sampling interval of a detector, and a response. 
         [0003]    PTL 1 discloses a technique for acquiring a correction value using data or the like of a column at the time of conversion of a measuring method of a certain device (conventional liquid chromatograph) to a measuring method of another device (ultrahigh velocity liquid chromatograph) with linear velocity (velocity at which a certain component passes through a column) which is higher than that of the certain device. 
       CITATION LIST 
     Patent Literature 
       [0000]    
       
         
           
             PTL 1: JP-A-2009-281897 
           
         
       
     
       SUMMARY OF INVENTION 
     Technical Problem 
       [0005]    However, in a case where the same measuring method is used in liquid chromatographs different from each other, the retention time or the degree of separation of the chromatographs may vary due to differences between tube diameters, dead volume of pumps, liquid mixing performance of mixers, dead volume of samplers, sample diffusion capacities other than columns, and detectors. 
         [0006]    On the contrary, for example, a user who introduces a new liquid chromatograph for pharmaceutical development or the like wants to obtain the same measurement results as those of a device in the related art without developing a new measuring method even when the new device is used in many cases. 
         [0007]    However, the same measurement results cannot be obtained between devices whose specifications are different from each other as described above using the technique disclosed in PTL 1. 
         [0008]    For this reason, in the technique in the related art, a known method cannot be used when a device is changed and a different method needs to be developed for each device. 
       Solution to Problem 
       [0009]    According to an aspect in order to solve the above-described problems, there is provided a liquid chromatograph including a liquid chromatograph unit which includes an elution unit sending an eluent to a detecting unit; and a control unit which controls elution performed by the elution unit based on a predetermined time table, in which the control unit stores an elution response of the liquid chromatograph unit to be obtained when a predetermined command value is input to the elution unit and an elution response of another liquid chromatograph to be obtained when the command value is input to another elution unit of another liquid chromatograph and converts the time table based on the elution response and another elution response such that an elution profile at the time when the elution unit is controlled by the liquid chromatograph unit based on the time table approaches another elution profile at a time when another elution unit is controlled by another liquid chromatograph based on the time table, and controls the elution unit based on the converted time table. 
         [0010]    In addition, the converted time table is divided into a plurality of regions, approximate calculation is performed for each of the divided regions, and the size of the divided regions is changed based on the results of the approximate calculation. 
       Advantageous Effects of Invention 
       [0011]    According to the above-described aspect, a measuring method related to one device can be used in another device and thus the measuring method can be seamlessly transferred between devices. 
         [0012]    In addition, when a fluid is controlled based on a time table after system conversion, it is possible to control an elution unit with high precision and high efficiency in regard to information related to complicated and various time tables. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0013]      FIG. 1  is a diagram illustrating a system configuration of a liquid chromatograph according to the present invention. 
           [0014]      FIG. 2  is a diagram illustrating a system channel of the liquid chromatograph according to the present invention. 
           [0015]      FIG. 3  is a flowchart illustrating a method of processing a system conversion program according to the present invention. 
           [0016]      FIG. 4  is a diagram illustrating a part of a system configuration of a data processing device  106  and a system conversion processing device  107  according to a system conversion process of the present invention. 
           [0017]      FIG. 5  is a view illustrating an example of a display screen of an output device  109  of the present invention. 
           [0018]      FIG. 6  is a diagram illustrating an example of a time table (command value) to be input in order to acquire an elution response of the liquid chromatograph according to the present invention. 
           [0019]      FIG. 7  is a diagram illustrating an example of an elution time table of the present invention. 
           [0020]      FIG. 8  is a graph illustrating an elution time table before system conversion. 
           [0021]      FIG. 9  is a graph illustrating an elution time table after system conversion. 
           [0022]      FIG. 10  is a diagram illustrating a part of a system configuration of a data processing device  106  and a system conversion processing device  107  according to Example 2 of the present invention. 
           [0023]      FIG. 11  is a flowchart illustrating a basic process of a process of approximate calculation according to the present invention. 
           [0024]      FIG. 12  is a graph illustrating an example of an elution time table after the process of approximate calculation according to the present invention. 
           [0025]      FIG. 13  is a diagram illustrating a table of results of approximate calculation. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0026]    Hereinafter, embodiments of the present invention will be described in detail in reference to the accompanying drawings. 
       Example 1 
       [0027]      FIG. 1  illustrates a system configuration of a liquid chromatograph in the present invention. The liquid chromatograph illustrated in the figure includes a liquid chromatograph unit  101  in which separation and analysis of a sample are performed and a control unit  110  which is a control device for controlling each device related to the liquid chromatograph unit  101  based on a predetermined measuring method. 
         [0028]    The liquid chromatograph unit  101  includes a pump (elution unit)  102  that sends an eluent based on a command from the control unit  110 ; an auto sampler (sample injection unit)  103  that injects a sample with respect to the eluent from the pump  102  based on a command from the control unit  110 ; a column oven (separating unit)  104  that holds the temperature of an analysis column  207  (see  FIG. 2 ) based on a command from the control unit  110 ; and a detector (detecting unit)  105  that detects a component eluted from the analysis column  207  and converts the component into an electrical signal to be output to the control unit  110 . 
         [0029]    The control unit  110  includes a data processing device  106  that transceives commands and data among respective devices related to the liquid chromatograph unit  101 ; an input device (for example, a pointing device, a keyboard, and a tablet)  108  to which a command or the like from an operator is input; a system conversion processing device  107  that performs a process (system conversion process) of converting a measuring method input through the input device  108 ; and an output device  109  on which detection results of a detector  105  and a graphical user interface (GUI) related to various operations of the liquid chromatograph unit  101  and the control unit  110  are shown. Measurement values of each component detected by the detector  105  are taken in the data processing device  106  and analysis results of samples are transmitted to and displayed on the output device  109 . 
         [0030]    In the measuring method, data columns (hereinafter, also referred to as a “time table” or “elution time table”) which are time series of control command values (target values of the elution profile) to the pump  102  and in which a time change of the elution profile of an eluent due to the pump  102  is determined in advance are included. Examples of elution profiles include the flow rate and the pressure of an eluent and the mixing ratio of respective eluents in a predetermined flow rate in a case where a plurality of eluents are present. Specific examples of the time table of the pump  102  will be described below. In the present embodiment, system conversion will be described by exemplifying a case where measurement in another liquid chromatograph is reproduced by converting the time table of the pump  102 . As described below, the system conversion device  107  performs conversion of the time table (system conversion) based on a difference between elution responses of respective liquid chromatographs such that the “elution profile” shown when the same time table is used in another liquid chromatograph is actually shown in the liquid chromatograph of the present embodiment. 
         [0031]    The elution response indicates an actual elution profile of each liquid chromatograph obtained when a predetermined command value (specific examples of the command value will be described below) is input to the pump  102 . For example, in a case where the same command value is input to a plurality of liquid chromatographs, the elution profiles vary due to a difference among various specifications (for example, differences between tube diameters, dead volumes of pumps, liquid mixing performance of mixers, dead volumes of samplers, sample diffusion capacities other than columns, and detectors) in the plurality of liquid chromatographs. That is, an elution response becomes an intrinsic value of each liquid chromatograph. 
         [0032]    As a method of measuring an actual elution response (elution profile), a method of measuring absorbance of an eluent sent by the pump  102  based on a predetermined command value can be exemplified. The detector  105  installed in the liquid chromatograph unit  101  can be used as means for measuring the absorbance of an eluent. 
         [0033]    In addition, it is preferable that command values input to pumps of respective liquid chromatographs when elution profiles are acquired are the same as each other, but the command values may not be perfectly matched if the detection results of the detector  105  are ultimately the same. 
         [0034]      FIG. 2  illustrates a system channel of the liquid chromatograph in the present invention. In addition, the same elements in the figure described above are denoted by the same reference numerals and the description thereof is not repeated (the same applies hereinafter). The liquid chromatograph unit  101  illustrated in the figure includes the pumps  102  (a pump  102 A sending out an eluent  201 A and a pump  102 B sending out an eluent  201 B, a mixer  203 , the auto sampler  103 , the column oven  104 , and the detector  105 . 
         [0035]    The pumps  102 A and  102 B pump the eluents  201 A and  201 B based on the contents of the time table stored in the data processing device  106 . The eluents sent from the pump  102 A and  102 B are mixed by the mixer  203  and then sent to the column oven  104  through the auto sampler  103 . Meanwhile, a sample is injected from the auto sampler  103  and sent to the analysis column  207 . The detector  105  detects sample components having passed through the analysis column  207  and the detection results are stored in a storage device of the data processing device  106  of the control unit  110 . 
         [0036]      FIG. 4  illustrates a part of the system configuration diagram of the data processing device  106  and the system conversion processing device  107  of the present invention. Further, although not illustrated in the figure, the data processing device  106  and the system conversion processing device  107  respectively include an arithmetic processing device (for example, a CPU) serving as arithmetic means for performing various programs; storage devices (for example, a semiconductor memory such as a ROM, a RAM, or a flash memory, and a magnetic storage device such as a hard disk) serving as storage means for storing the programs and various pieces of data; and an input and output arithmetic processing device for controlling input and output of data, commands, and the like to respective devices  101 ,  106 ,  107 ,  108 , and  109 . 
         [0037]    In  FIG. 4 , the data processing device  106  includes a time table input unit  405 , a time table storage unit  406 , and a pump control unit  407 . 
         [0038]    The time table input unit  405  is a portion to which a time table related to the control of the pumps  102  (pumps  102 A and  102 B) is input from the outside. Examples of the method of inputting the time table include a method of inputting the time table through a storage medium in which the time table is stored and a method of inputting the time table using communication through another computer and a network in addition to a method of inputting the time table using the input device  108 . 
         [0039]    The time table storage unit  406  is a portion in which a time table input through the time table input unit  405  and a time table converted by a conversion time table calculator  404  in the system conversion processing device  107  described below are stored. 
         [0040]    The pump control unit  407  is a portion that controls the pumps  102  (pumps  102 A and  102 B) of the liquid chromatograph unit  101  based on the time table stored in the time table storage unit  406 . In a case where data to which the conversion time table calculator  404  is converted is selected as a time table used here, the pump control unit  407  controls the pumps  102  (the pump  102 A and the pump  102 B) based on the time table. 
         [0041]    In  FIG. 4 , the system conversion processing device  107  includes an elution response input unit  401 , an elution response storage unit  402 , a re-calculator  403 , and the conversion time table calculator  404 . 
         [0042]    The elution response input unit  401  is a portion to which elution responses of a plurality of liquid chromatographs including the liquid chromatograph unit  101  are input. 
         [0043]    Examples of the method of inputting elution responses to the input unit  401  include a method of inputting the elution responses through a storage medium in which the elution responses are stored and a method of inputting the elution responses using communication through another computer in which the elution responses are stored and a network in addition to a method of inputting the elution responses using the input device  108 . 
         [0044]    The elution response storage unit  402  is a portion in which the elution responses of a plurality of liquid chromatographs (including the liquid chromatograph unit  101 ) input through the elution response input unit  401  are stored. 
         [0045]    The trans calculator  403  is a portion that calculates a trans (trans(t)) between elution responses of the liquid chromatograph unit  101  and another liquid chromatograph. The contents of the calculation will be described below. 
         [0046]    The conversion time table calculator  404  is a portion that stores a time table which is stored in the time table storage unit  406  and used for sample analysis based on the trans of the elusion response calculated by the trans calculator  403 . As a case where a time table is converted by the conversion time table calculator  404 , a case where measurement results obtained in a certain device (liquid chromatograph A) using a predetermined time table are reproduced in another device (liquid chromatograph B) can be exemplified. A specific conversion process is as described above with reference to  FIG. 3 . 
         [0047]      FIG. 3  is a flowchart showing a method of processing a system conversion program in the present invention. A method of controlling the pump  102  using system conversion will be described below with reference to this figure. 
         [0048]    Here, under the assumption that the two liquid chromatographs A and B which are different from each other and a common time table related to control of pumps of the respective liquid chromatographs A and B are present, a case of performing system conversion of the liquid chromatograph B such that measurement results obtained when the pump is controlled by the liquid chromatograph B based on the time table approach measurement results obtained when the pump is controlled by the liquid chromatograph A based on the time table will be described. Here, the description will be made under the assumption that the liquid chromatograph B corresponds to a liquid chromatograph illustrated in  FIGS. 1 and 2  and the liquid chromatograph A has the same configuration as that illustrated in at least  FIG. 2 . 
         [0049]    In  FIG. 3 , first, the system conversion processing device  107  acquires elution responses of the liquid chromatograph A and the liquid chromatograph B through the elution response input unit  401  (see  FIG. 4 ) and stores the elution responses in the elution response storage unit  402  (S 301 ). The elution responses of the liquid chromatograph A and the liquid chromatograph B are derived from respective tube systems, the dead volumes of the pumps  102 A and  102 B, sample diffusion capacities other than columns, and the detectors  105 . Here, the elution response of the liquid chromatograph A is set as RA(t) and the elution response of the liquid chromatograph B is set as RB(t). 
         [0050]    The elution responses RA(t) and RB(t) are obtained by measuring actual elution profiles of respective liquid chromatographs A and B when the same command value is input to the pumps  102 A and  102 B of the liquid chromatographs A and B. The elution responses (actual elution responses) of the liquid chromatographs A and B can be acquired by measuring the absorbance of the eluent sent through the pumps  102 A and  102 B and the mixer  203  using the detectors  105  of respective devices A and B. The elution responses RA(t) and RB(t) acquired in this manner are stored in the elution response storage unit  402  through the input device  108  or the like. 
         [0051]    At this time, a process of increasing the S/N ratio of the elution response if necessary (S 302 ) and a process of adjusting data sampling periods to be the same among elution responses (S 303 ) are performed. 
         [0052]    The process of increasing the S/N ratio of the elution response obtained through actual measurement can be performed by carrying out a smoothing process according to any one of a moving-average method, a Savitzky-Golay method, a Kawata-Minami method, and a frequency domain method, or a combination of these. 
         [0053]    Further, as a method of adjusting the data sampling periods among elution responses, it is preferable to use interpolation such as linear interpolation, spline interpolation, polynomial interpolation, continued fraction interpolation, or a trigonometric function. 
         [0054]    In the liquid chromatograph, the measurement results (actual elution profile of an eluent) obtained when the pumps  102 A and  102 B are controlled based on the elution time table (that is, command values related to a time change of mixing ratios of the eluent  201 A and the eluent  201 B) as illustrated in  FIG. 7  are shown by the following equations (1) and (2) using the elution responses RA(t) and RB(t). Further, the actual elution profile of an eluent can be acquired by measuring the absorbance of the eluent using the detector  105  in the same manner as that of the elution response. Here, the symbol “*” represents a convolution operation. 
         [0000]      [MATH. 1] 
         [0000]      Measurement results of liquid chromatograph  A  when Time Table is input=Time Table* RA ( t )  Equation (1)
 
         [0000]      [MATH. 2] 
         [0000]      Measurement results of liquid chromatograph  B  when Time Table is input=Time Table* RB ( t )  Equation (2)
 
         [0055]    As is obvious from the equations (1) and (2), a difference between the elution responses RA(t) and RB(t) of the respective liquid chromatographs A and B becomes a difference in the measurement results in a case where the same time table (Time Table) is input to the respective liquid chromatographs A and B. 
         [0056]    Next, in the system conversion processing device  107 , the trans (Trans(t)) between the elution responses RA(t) and RB(t) of the liquid chromatographs A and B is acquired by the trans calculator  403  (S 304 ). 
         [0000]      [MATH. 3] 
         [0000]        RA ( t )= RB ( t )*Trans( t )=∫ −∞   ∞ ( t ′)·Trans( t−t ′) dt′    Equation (3)
 
         [0057]    Here, the trans (Trans(t)) between the elution responses of the liquid chromatographs A and B is calculated by deconvolution calculation of the above-described equation (3). A time table (Time Table B(t)) made in order to obtain the same measurement results as those of the liquid chromatograph A in the liquid chromatograph B is calculated by the following equation (4) using the original time table (Time Table A(t)) and the Trans(t). For this reason, the conversion time table calculator  404  of the system conversion processing device  107  calculates the time table (Time Table B(t)) made in consideration of the trans between the elution responses RA(t) and RB(t) of the liquid chromatographs A and B based on the equation (4) while reading the time table (Time Table A(t)) which is a target to be converted from the time table storage unit  406  (S 305 ). 
         [0000]      [MATH. 4] 
         [0000]      Time Table  B ( t )=Time Table  A ( t )*Trans( t )=∫ −∞   ∞ Time Table  A ( t ′)·Trans( t−t ′) dt′   Equation (4)
 
         [0058]    The conversion time table calculator  404  outputs the time table (converted time table: Time Table B(t)) calculated in S 305  to the time table storage unit  406  of the data processing device  106  (S 306 ). The pump control unit  407  of the data processing device  106  controls the pumps  102 A and  102 B based on the time table (Time Table B(t)) (S 307 ). In this manner, since the time table (Time Table B(t)) necessary for obtaining the same measurement results as those of the liquid chromatograph A in the liquid chromatograph B can be shown by the convolution of the trans (Trans(t)) between the elution responses of the liquid chromatographs A and B and the existing time table (Time Table A(t)), the same measurement results as those of the liquid chromatograph A can be obtained in the liquid chromatograph B using the existing time table (Time Table A(t)) when the trans (Trans(t)) between the elution responses is calculated. 
         [0059]    Further, in the present example, as the hardware configuration at the time of acquiring the elution response, a hardware configuration in which the detector  105  is directly connected to an outlet of the auto sampler  103  to which the analysis column  207  is generally connected can be exemplified. The elution response can be acquired by measuring the absorbance of the eluent sent from the pump  102 A and the pump  102 B using the detector  105 . By employing such a configuration, the elution response caused by the pumps and the auto sampler can be obtained. In addition, the detector  105  may be normally connected to the outlet of the auto sampler  103  through the analysis column  207 . In the latter case, a resistance tube in place of the analysis column  207  is connected to the outlet of the auto sampler  103 , the detector  105  is connected to the resistance tube, and the elution response may be acquired. Moreover, from a viewpoint of acquiring the elution response, it is preferable that the resistance pipe and the column have a low capacity since the influence of the resistance tube or the column is suppressed. In addition, the case where the sample injection unit is the auto sampler  103  has been described here, but the sample injection unit may be a manual injector. 
         [0060]      FIG. 5  illustrates a display screen of the output device  109  at the time of setting the system conversion according to the present embodiment. 
         [0061]    An elution response curve display unit  506 , a gradient table display unit  510 , a gradient curve display unit  512 , a device selection button  501 , a calculation execute button  502 , a condition setting button  503 , a storage button  504 , a cancel button  505 , a message display unit  511  are provided on the display screen illustrated in the figure. 
         [0062]    The elution response curve display unit  506  is a portion on which a command value  507  used for measuring an elution response, an elution response  508  by itself (liquid chromatograph B), and an elution response  509  of another device (liquid chromatograph A) which reproduces measurement results are displayed. In the illustrated example, it is understood that the command value  507  is stepwise and the liquid chromatograph B (elution response  508 ) responds more rapidly compared to the liquid chromatograph A (elution response  509 ). Specific examples of the command value  507  will be described below. 
         [0063]    The gradient time table display unit  510  is a portion on which a time table (time table before being converted) used for sample measurement is displayed. In the illustrated example, a time table which is the same as that illustrated in  FIG. 7  is used and displayed. The time table being used for measurement may be newly set by being input to a table on the display screen of the output device  109  through the input device  108  or the existing time table may be read from the time table storage unit  406 . 
         [0064]    The gradient curve display unit  512  is a portion on which a graph shape  513  of a time table displayed on the gradient table display unit  510 ; an actual elution profile (actual gradient curve)  514  when the liquid chromatograph B is controlled by itself (liquid chromatograph B) based on the time table; and an actual elution profile (actual gradient curve)  515  at the time when measurement results of another device (liquid chromatograph A) are reproduced by itself based on the trans between the time table and the elution profile are displayed. 
         [0065]    The device selection button  501  is a button for selecting another device at the time when measurement results are reproduced. As a specific method of selecting a device, for example, when the device selection button  501  is pressed by the input device  108  such as a pointing device or the like, a plurality of device names in which elution responses are stored in the elution response storage unit  402  are displayed on a screen and one of the devices is selected by the operator through the input device  108 . 
         [0066]    The calculation execute button  502  is a button for executing a process (S 304 ) of acquiring a trans between elution responses of the device (liquid chromatograph A) selected through the device selection button  501  and itself (liquid chromatograph B) and a process (S 305 ) of acquiring a time table made in consideration of the trans using the system conversion processing device  107 . 
         [0067]    The condition setting button  503  is a button for outputting a time table (converted time table) calculated by pressing the calculation execute button  502  to the data processing device  106  (S 306 ) and setting the time table to be used for control of the pumps  102 . 
         [0068]    Here, when the storage button  504  is clicked, the results of the system conversion under the above-described conditions can be stored in the storage unit (not illustrated) of the data processing device. 
         [0069]    Further, when the cancel button  505  is clicked, the arithmetic processing in the past is cancelled and the state can be returned to the state before the system conversion process is performed. 
         [0070]    The message display unit  511  is a portion on which messages or the like related to the operation and the process of the liquid chromatograph are displayed. 
         [0071]      FIG. 6  illustrates an example of the elution time table (command value) to be input in order to acquire elution responses of the respective liquid chromatographs. The command value regulates the control of the pumps  102  at the micro time of an order of several milliseconds to several seconds. In  FIGS. 6(A) to 6(F) , the timing at which the mixing ratio of an eluent is switched in each mobile phase varies. In addition, “B %” in  FIG. 6  indicates a composition ratio of the eluent  201 B in the mobile phase. Hereinafter, specific examples of the command value to be input to the pumps  102  at the time when the elution response is acquired will be described below with reference to the figure. 
         [0072]    First, as an example of the command value, a command value that changes the mixing ratio of two types of eluents while the total flow rate of two types of the eluents (eluents  201 A and  201 B) is maintained to be constant as the step function illustrated in  FIG. 6(A)  can be exemplified. As the method of calculating the elution response in this case, a method of calculating the elution response by normalizing a difference between an observation value at the time when the observation value before an eluent is switched on a gradient curve to be measured enters a static state and an observation value at the time when the observation value after the eluent is switched on the gradient curve enters a static state is set as 1 and calculating a differential or a delta of the gradient curve can be exemplified. 
         [0073]    In addition, as an example of the command value, a command value that switches an eluent as in the example of  FIG. 6(B) , that is, H 1 ( t ) of the following equation (5) can be exemplified. In addition, a difference between an observation value at the time when the observation value before an eluent is switched on a gradient curve enters a static state and an observation value at the time when the observation value after the eluent is switched on the gradient curve enters a static state is normalized as 1. The elution response is acquired by calculating a differential or a delta of the gradient curve. 
         [0000]    
       
         
           
             
               
                 
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         [0074]    Here, A 11  and A 12  represent a constant and A 12  is set to be larger than A 11 . t 1  and t 2  are not in a relationship of “t 1 =t 2 .” It is preferable that a difference between t 2  and t 1  is in the range of milliseconds to seconds. 
         [0075]    Further, H 1 ( t ) is continuous in a case of “t=t 1 , t 2 ” as a boundary condition. That is, a relationship of “J 1 ( t   1 )=A 11 ” is satisfied in a case of “t=t 1 ” and a relationship of “J 1 ( t   2 )=A 12 ” is satisfied in a case of “t=t 2 .” 
         [0076]    J 1 ( t ) is a monotonically increasing function and examples of J 1 ( t ) include a polynomial, an exponential function, and a function combining these. 
         [0077]    Moreover, as an example of the command value, a command value of switching an eluent as in a case of a boxcar function illustrated in  FIG. 6(C)  can be exemplified. The area of a peak after the gradient curve is measured is calculated and the gradient curve is normalized such that the area of the peak becomes 1. 
         [0078]    Moreover, as an example of the command value, a command value of switching an eluent as in a case illustrated in  FIG. 6(D) , that is, H 2 ( t ) of the following equation (6) can be exemplified. 
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                             J 
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                             22 
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                               ( 
                               t 
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                                 3 
                               
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                                 2 
                               
                             
                             ) 
                           
                         
                       
                       
                         
                           
                             J 
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                             21 
                              
                             
                                 
                             
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                               ( 
                               t 
                               ) 
                             
                           
                         
                         
                           
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                                 1 
                               
                             
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                             2 
                           
                         
                         
                           
                             ( 
                             
                               
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                   Equation 
                    
                   
                       
                   
                    
                   
                     ( 
                     6 
                     ) 
                   
                 
               
             
           
         
       
     
         [0079]    Here, A 2  represents a constant. Further, in regard to t 1 , t 2 , and t 3 , relationships of “t 1 =t 2 ” and “t 2 =t 3 ” are not satisfied. It is preferable that a difference between t 1  and t 2  and a difference between t 2  and t 3  are in the range of milliseconds to seconds. 
         [0080]    H 2 ( t ) of the equation (6) is continuous in a case of “t=t 1 , t 2 , t 3 ” as a boundary condition. That is, a relationship of “J 21 ( t   1 )=A 2 ” is satisfied in a case of “t=t 1 ,” a relationship of “J 21 ( t   2 )=J 22 ( t   2 )” is satisfied in a case of “t=t 2 ,” and a relationship of “J 22 ( t   3 )=A 2 ” is satisfied in a case of “t=t 3 .” J 21 ( t ) of Math.  5  is a monotonically increasing function and examples of J 21 ( t ) include a monotonically increasing polynomial, a monotonically increasing exponential function, and a function combining these. J 22 ( t ) of the equation (6) is a monotonically decreasing function and examples of J 22 ( t ) include a monotonically decreasing polynomial, a monotonically decreasing exponential function, and a function combining these. 
         [0081]    As another example of the command value, a command value of switching an eluent as in a case of  FIG. 6(E) , that is, H 3 ( t ) of the following equation (7) can be exemplified. The eluent is switched on the gradient curve, a second order differential of the gradient curve is calculated, and the area of the peak is normalized as 1. 
         [0000]    
       
         
           
             
               
                 
                   [ 
                   
                     MATH 
                     . 
                     
                         
                     
                      
                     7 
                   
                   ] 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
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                               33 
                             
                           
                         
                         
                           
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                             31 
                           
                         
                         
                           
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                   Equation 
                    
                   
                       
                   
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                     ( 
                     7 
                     ) 
                   
                 
               
             
           
         
       
     
         [0082]    Here, A 31 , A 32 , and A 33  of the equation (7) represent a constant. In addition, t 1  and t 2  of the equation (7) are not in a relationship of “t 1 =t 2 .” It is preferable that a difference between t 2  and t 1  is in the range of milliseconds to seconds. 
         [0083]    H 3 ( t ) of the equation (7) is continuous in a case of “t=t 1 , t 2 ” as a boundary condition. That is, a relationship of “J 3 (t 1 )=A 31 ” is satisfied in a case of “t=t 1 ” and a relationship of “J 3 ( t   2 )=A 32 ·t 2 +A 33 ” is satisfied in a case of “t=t 2 .” J 3 ( t ) of the equation (7) is a monotonically increasing function. Examples of J 3 ( t ) of the equation (7) may include a polynomial, an exponential function, and a function combining these. 
         [0084]    Further, as an example of the command value, a command value of switching an eluent as in a case of  FIG. 6(F) , that is, H 4 ( t ) of the following equation (8) can be exemplified. The elution response can be acquired by inputting the time table and measuring the gradient curve. For example, the eluent is switched on the gradient curve, a second order differential of the gradient curve is calculated, and the area of the peak is normalized as 1. 
         [0000]    
       
         
           
             
               
                 
                   [ 
                   
                     MATH 
                     . 
                     
                         
                     
                      
                     8 
                   
                   ] 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
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                     ( 
                     8 
                     ) 
                   
                 
               
             
           
         
       
     
         [0085]    Here, A 41 , A 42 , and A 43  represent a constant and A 42  is set to be larger than A 41 . 
         [0086]    H 4 ( t ) of the equation (8) is continuous in a case of “t=t 1 ” as a boundary condition. That is, a relationship of “H 4 ( t   1 )=A 42 ·t 1 +A 43 ” is satisfied in a case of “t=t 1 .” 
         [0087]    As illustrated above, a plurality of methods of determining elution responses are present. In Math. 1, it is preferable that the method of determining the elution response of the liquid chromatograph A is the same as the method of determining the elution response of the liquid chromatograph B, but the determining methods may be different from each other. 
         [0088]    In this manner, an elution response of a liquid chromatograph can be acquired corresponding to elution responses of various gradients. 
       Example 2 
       [0089]      FIG. 7  illustrates an elution time table before system conversion. In this case, in general, the total required time is divided into a plurality of intervals, the starting time and the ending time are set, a program for changing the composition ratio among respective eluents between the starting time and the ending time of respective intervals is designated, and data is transmitted to pumps. In addition, a graph illustrated in  FIG. 8  is created by connecting data of acquired straight lines or elementary functions. 
         [0090]    Here, in a case where system conversion is performed using the above-described method, since a process is carried out such that one liquid chromatograph obtains the same measurement results as those of another liquid chromatograph, the elution time table made in consideration of the trans between the elution responses of both liquid chromatographs has a shape of a complicated curve which cannot be shown by straight lines or elementary functions illustrated in  FIG. 9  and thus the amount of information becomes enormous. Accordingly, in a case where such data is transmitted to the pumps, this takes a long time and there is a possibility that the pumps cannot be accurately controlled while the data is transmitted. Further, a problem in that securing of the memory capacity has a cost is generated. 
         [0091]    Here, in the present example, a data processing method when data is transmitted to the pumps  102  by performing the system conversion process described in Example 1 will be described. 
         [0092]      FIG. 10  illustrates a part of a system configuration diagram of the data processing device  106  and the system conversion processing device  107  according to Example 2 of the present invention. The figure is different from the configuration diagram illustrated in  FIG. 4  in that the data processing device  106  includes an approximating calculator  1001  and an approximate calculation data storage unit  1002 . 
         [0093]    The elution time table after system conversion between liquid chromatographs is calculated by the conversion time table calculator  404  in the system conversion processing device  107  in  FIG. 10  and stored in the time table storage unit  406  of the data processing device  106 . 
         [0094]    An approximation curve related to a set approximating interval is calculated by the approximating calculator  1001  with respect to the elution time table stored in the time table storage unit  406  and the results are stored in the approximate calculation data storage unit  1002 . In the approximate calculation data storage unit  1003 , the stored approximating interval and data related to the created approximation curve are transmitted to the pump control unit  407 . 
         [0095]    Next, a specific calculation method in the approximating calculator  1001  will be described below. 
         [0096]      FIG. 11  is a flowchart illustrating a basic process of the approximate calculation process of the present invention. In the present example, the elution time table is divided into a plurality of intervals such that the elution data amount and the calculation time are reduced within an acceptable error of approximation and is approximated using elementary functions or the like for each interval. 
         [0097]    First, values of acceptable errors, start points and end points of intervals at which approximate calculation is performed, and serial numbers of the intervals are set (S 1101 ). At this time, an interval to be set has a minimum range in which desired approximate calculation is possible. For example, when third order polynomial approximation is performed, an interval is determined so as to include four points which is the minimum as the sampling interval. 
         [0098]    Subsequently, the elution time table is obtained by approximate calculation using a polynomial within the set interval (S 1102 ) and the approximation error is acquired (S 1103 ). The acquired approximation error is compared to the value of the acceptable error set in advance in S 1101  (S 1104 ) and the calculation results are recorded in a case where the acquired approximation error exceeds the acceptable error (S 1107 ). Here, start points, end points, coefficients of polynomials, interval numbers, and the like are recorded. 
         [0099]    At this time, the first result is recorded when the approximate calculation is carried out for the first time and the previous result (previous result of the calculation) is recorded when the approximate calculation is carried out for the second or subsequent time (S 1107 ). 
         [0100]    After the results are recorded, completion determination of transfer data of an elution unit is performed based on whether the calculated interval is final (S 1108 ). In a case where the calculated interval is final, the calculation result is output to the elution unit and the process ends (S 1110 ). Meanwhile, in a case where the calculated interval is not final, the calculation result is updated to the interval number in which subsequent approximate calculation is performed (S 1109 ) and the process is returned to S 1101  again. 
         [0101]    Moreover, when the approximation error does not exceed the acceptable error, it is determined whether extension of the interval is carried out (S 1105 ). Here, it is determined that the approximating interval is set to be as long as possible in order to reduce the amount of information to be sent to the elution unit. However, since it takes time to acquire the approximation curve when the interval becomes extremely long, the length of the interval, that is, the upper limit of the number of sampling points from the start point to the end point is determined and it is determined whether extension of the interval is possible based on the upper limit. 
         [0102]    In a case where extension of the interval is possible, the number of sampling points is increased (S 1106 ). At this time, it is preferable to increase the sampling points one by one in order to improve the precision. Further, the above-described approximate calculation is performed again in a newly set interval (S 1102 ). 
         [0103]      FIG. 12  is a graph illustrating the elution time table after the approximate calculation. As illustrated in the figure, the elution time table after the system conversion process is performed is divided into the most suitable approximating intervals. 
         [0104]    Here, as described above, when the interval approximated in the approximate calculation becomes longer, it takes a long time for carrying out the calculation process. The time for the approximate calculation is exponentially increased with respect to the number of pieces of data. The relationship between a time T and the number n of pieces of data of the approximate calculation is shown by the equation (8). At this time, the value acquired by the equation 9 can be used as an upper limit J of the length of the approximating interval. 
         [0000]      [MATH. 9] 
         [0000]        T=A ×exp( Bλn   Equation (9)
 
         [0000]      [MATH. 10] 
         [0000]        J= 1/ B   Equation (10)
 
         [0105]    Upper Limit of Length of Approximate Interval 
         [0106]    In the present example, as a method of approximation of the elution time table at the set approximating interval using elementary functions, a method of approximation using a polynomial as described above can be performed. In this case, a pseudo inverse matrix of Moore-Penrose may be used in the approximate calculation. 
         [0107]    In the present example, the approximation curve is compared to the elution time table, an absolute value of a difference between an elution time table Yi and an approximate value yj thereof in the equation (9) is calculated in the entire range of the approximating interval, and then the absolute value can be set as the maximum value thereof as a method of calculating the approximation error. 
         [0000]      [MATH. 11] 
         [0000]      Max(| Yi−yj |)  Equation (11)
 
         [0108]    In the present embodiment, data stored in an approximation curve result storage unit is described with reference to a case where a third order polynomial shown in the equation (11) is set as an approximation curve.  FIG. 13  is a diagram showing a table of approximate calculation results. As illustrated in the figure, for example, serial numbers at respective approximating intervals, the starting time at respective approximating intervals, the ending time at respective approximating intervals, a coefficient a 0  of a constant term of a polynomial, a coefficient a 1  of t, a coefficient a 2  of t 2 , and a coefficient a 3  of t 3  at respective approximating intervals are recorded. 
         [0000]      [MATH. 12] 
         [0000]        a   0   +a   1   t+a   2   t   2   +a   3   t   3   Equation (12)
 
       REFERENCE SIGNS LIST 
       [0000]    
       
           101 : Liquid chromatograph unit 
           102 : Pump 
           103 : Auto sampler 
           104 : Column oven 
           105 : Detector 
           106 : Data processing device 
           107 : System conversion processing device 
           108 : Input device 
           109 : Output device 
           110 : Control unit 
           201 A,  201 B: Eluent 
           203 : Mixer 
           205 : Washing solution 
           207 : Analysis column 
           401 : Elution response input unit 
           402 : Elution response storage unit 
           403 : Trans calculator 
           404 : Conversion time table calculator 
           405 : Time table input unit 
           406 : Time table storage unit 
           407 : Pump control unit 
           501 : Device selection button 
           502 : Calculation execute button 
           503 : Condition setting button 
           504 : Storing button 
           505 : Cancel button 
           506 : Elution response curve display unit 
           507 : Command value 
           508 : Elution response of liquid chromatograph B 
           509 : Elution response of liquid chromatograph A 
           510 : Gradient time table display unit 
           511 : Message display unit 
           512 : Gradient curve display unit 
           513 : Graph shape of time table 
           514 : Gradient curve of liquid chromatograph B 
           515 : Gradient curve of liquid chromatograph A 
           1001 : Approximating calculator 
           1002 : Approximate calculation data storage unit 
           1201 ,  1202 : Approximating interval 
           1203 : Elution time table after system conversion