Abstract:
Provided is a waveform processing assistance system for helping users determine the value of a parameter which is necessary in a waveform processing method for determining the rising and falling points of a peak and whose validity cannot be easily and intuitively determined The system includes: a waveform displayer for showing, on a display screen, a waveform including a peak; a marker displayer for showing, on the display screen, a marker which is capable of being moved by a user; and a slope information displayer for showing information related to the slope of the waveform at a point lying on the waveform and meeting the marker, or at a point which lies on the waveform, which meets the marker, and at which a predetermined operation has been performed by the user. Examples of the slope-related information include a numerical value of the slope, a tangent, and a grid.

Description:
TECHNICAL FIELD 
     The present invention relates to a method and system for assisting an analysis of a peak waveform of measurement data obtained with a chromatograph system, spectrometer or other devices. 
     BACKGROUND ART 
     Some measurement systems, such as a chromatograph system or a spectroscopic analyzer, produce measurement data in the form of waves with one or more peaks. In those systems, the result of a measurement is analyzed by determining the width, intensity, area and other values of a peak waveform of the measurement data by waveform processing including the steps of determining the rising and falling points of the peak, setting the baseline, and calculating a fitting curve using a Lorenz distribution function or Gaussian distribution function (see Patent Literature 1). 
     Correct determination of the rising and falling points of a peak is important since these points affect the value of the peak area. In a preparative chromatography, in which a specific target component in a sample being analyzed is preparative-separated based on the result of a chromatographic measurement, it is necessary to correctly determine the rising and falling points of the peak by waveform processing so as to minimize the amount of unwanted components to be mixed with the target component. 
     In a chromatograph system, two parameters called “Width” and “Slope” are used in the determination of the rising and falling points of a peak. 
     The parameter “Width” is the smallest value of the full width at half maximum (FWHM) by which a peak is identified in the waveform processing; a waveform whose FWHM is smaller than this value is identified as noise. The parameter “Width” is expressed in the same unit as the horizontal axis of the measurement data, e.g. in minutes as in the case of a chromatograph system or in 1/cm (or nm) as in the case of a spectroscopic analyzer. Therefore, users can intuitively determine whether or not the “Width” value is appropriate. 
     The parameter “Slope” is the critical value of the slope of a peak for locating the rising or falling point of the peak; the point at which the slope of the peak is equal to the critical value and around which the slope of the peak shows a predetermined increasing or decreasing tendency is identified as the rising or falling point of the peak. The parameter “Slope” is expressed in a complex unit in which the units of the horizontal and vertical axes are composed. Therefore, it is difficult for users to intuitively determine whether or not the “Slope” value is appropriate. 
     With such a technical background, efforts have been made to automatize the determination of the values of the two parameters (in particular, the determination of the “Slope” value) using a computer. In one method for determining an appropriate value of the “Slope”, a recommended value of the “Slope” for a peak waveform of measurement data is automatically calculated by determining the baseline of the waveform with a predetermined criteria. In another method, the rising and falling points of an actual peak is calculated by an analysis using predetermined values of the parameters “Width” and “Slope.” 
     The automatic determination of the values of the parameters “Width” and “Slope” using a computer is a standardized process and does not allow the rising or falling point of the peak to be arbitrarily selected as needed by users. For example, in a preparative chromatography, when a component other than a specific component has been found to be mixed in a preparative-separated sample, the user may desire to set the rising point of a peak at a later point in time and/or the falling point at an earlier point in time. However, the automatized process using a computer cannot flexibly deal with such situations. In such cases, the user needs to directly specify the values of the parameters “Width” and “Slope.” 
     However, specifying the value of the parameter “Slope” is difficult for those who are not accustomed to an analysis for the waveform processing. This is because, as explained earlier, it is difficult for users to intuitively determine whether or not the “Slope” value is appropriate. 
     In a component analysis using spectra, there is the case where a plurality of spectra which only differ from each other in peak intensity need to be superposed on each other for comparison. In this case, a spectrum whose peak intensity is lower than those of the other spectra may be obscured in the vicinity of the baseline. When the user directly specifies the values of the parameters “Width” and “Slope” and determines the rising and falling points of a peak in such a low-intensity spectrum, it is difficult to determine, from the screen display, whether or not the rising and falling points of the peak are appropriate. Therefore, the user needs to perform the cumbersome task of expanding the vertical axis of the spectrum whose peak intensity is low and then determining the rising and falling points of the peak by directly specifying the values of the parameters “Width” and “Slope.” 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: JP 2005-127814 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     The problem to be solved by the present invention is to help users determine the value of a parameter which is necessary in a waveform processing method for determining the rising and falling points of a peak and whose validity cannot be easily and intuitively determined. 
     Solution to Problem 
     A waveform processing assistance method according to the present invention aimed at solving the previously described problem is characterized in that information related to the slope of a peak waveform of measurement data at a point specified by a user is shown on a display screen on which the peak waveform is shown. 
     The “information related to the slope” (which may be hereinafter called the “slope-related information”) is one or more kinds of information selected from the group consisting of a numerical value of the slope, a tangent, and a grid. The specification of a point on a peak waveform by the user can be achieved, for example, by clicking a mouse at a desired point on a peak waveform shown on a display screen on which the peak waveform is shown, or by moving a cursor with cursor keys to a desired point on the peak waveform and performing a “specifying” operation at that point. If the display screen on which the peak waveform is shown is a touchscreen, the “specifying” operation can also be performed by touching a desired point on the screen with a pen-type input device (stylus pen) or a finger of the user. It is also possible to automatically select, as the “specified” point, a point on the peak waveform on which the mouse pointer or the cursor lies, without requiring the clicking or other special operation for the point specification. 
     When the position of the specified point on the peak waveform is changed, the display of the slope-related information also changes according to the change in the position. When the display range of the display screen is changed by some operation, such as the expanding of the vertical axis of the display screen on which the peak waveform is shown, the slope-related information such as the tangent and grid also changes according to that operation. 
     The grid minimally needs to include grid lines parallel to the tangent and may additionally include grid lines orthogonally or obliquely intersecting with the tangent. 
     A waveform processing assistance system according to the present invention aimed at solving the previously described problem includes: 
     a waveform displayer for showing, on a display screen, a waveform including a peak; 
     a marker displayer for showing, on the display screen, a marker which is capable of being moved by a user; and 
     a slope information displayer for showing, on the display screen, information related to the slope of the waveform at a point lying on the waveform and meeting the marker, or at a point which lies on the waveform, which meets the marker, and at which a predetermined operation has been performed by the user. 
     In the waveform processing assistance system according to the present invention, a waveform including a peak is shown on the display screen by the waveform displayer, and a marker is also shown on the display screen by the marker displayer. The marker can be moved by users. The slope information displayer shows, on the display screen, slope information at the point where the marker meets the waveform on the display screen, or slope information at the point where the marker meets the waveform and at which a predetermined specifying operation has been performed by the user. Using this function, the user can make the system show slope information at any point on the waveform on the display screen. 
     The “information related to the slope” is one or more kinds of information selected from the group consisting of a (numerical) value of the slope, a tangent, and a grid. An input device (such as a mouse or stylus pen) can be used for allowing users to move the marker. If a touchscreen is provided as the display screen, the touchscreen can serve as an input device for moving the marker. 
     Advantageous Effects of the Invention 
     For a waveform including a peak of measurement data, the information related to the slope of the waveform at an arbitrarily specified point is displayed on the display screen on which the peak waveform is shown. This information helps users intuitively determine the value of the slope of the peak or other parameters whose validity has conventionally been difficult to be intuitively determined. Therefore, even a user who is not accustomed to an analysis for the waveform processing can perform an analysis of a peak waveform of the measurement data. 
     In the case where a plurality of spectra which only differ from each other in peak intensity are shown in a superposed form, the displayed information enables users to determine whether or not the rising and falling points of the peak in a spectrum are appropriate, even if the spectrum has a low peak intensity. Accordingly, the values of the parameters necessary for the waveform processing can be quickly specified and the analysis time of the waveform processing can be shortened. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         Fig. 1  is a block diagram showing the main components of a preparative chromatograph system. 
         Fig. 2  is a block diagram showing the configuration of a waveform analyzer. 
         Fig. 3  shows one example of the display screen on which a peak waveform of a chromatogram in the first embodiment of the present invention is displayed. 
         Fig. 4  shows one example of the display screen on which a peak waveform of a chromatogram in the second embodiment of the present invention is displayed. 
         Fig. 5  shows one example of the display screen on which a peak waveform of a chromatogram in the third embodiment of the present invention is displayed. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Specific modes for carrying out the present invention are hereinafter described by means of embodiments. 
     First Embodiment 
     A waveform processing assistance system according to the first embodiment of the present invention is described with reference to  FigS. 1 and 2 . 
       Fig. 1  is a block diagram showing the main components of a preparative liquid chromatograph system in which the waveform processing assistance system  1  of the present embodiment is used. An eluent (mobile phase) held in an eluent tank  11  is drawn by a liquid-sending pump  12  and supplied into a column  14  via a sample injector  13  at a constant flow rate. A sample solution injected into the mobile phase in the sample injector  13  is carried by the mobile phase and introduced into the column  14 . While passing through this column  14 , the sample is separated into components, which are eluted from the column  14  at different points in time. A detector  15 , which is an ultraviolet-visible spectrophotometer, sequentially detects the components eluted from the column  14  and sends detection signals to a signal processor  21 . After passing through the detector  15 , the eluate is partially or entirely introduced into a fraction collector  16 . The signal processor  21  creates a chromatogram based on the detection signals received from the detector  15 . 
     Based on the peak waveform of the created chromatogram, the user needs to specify a section to be preparative-separated. As will be hereinafter described, the operator&#39;s workload in the waveform processing for the determination of the section for the preparative separation can be reduced by using the waveform processing assistance system  1 , which consists of a computer  10  having a predetermined processing program installed, an input unit  25  including an input device, and a display unit  26  having a display screen. The computer  10  has the aforementioned signal processor  21 , a waveform analyzer  22  and a preparative separation time determiner  23 . 
     Initially, a waveform display processor  27  of the waveform analyzer  22  displays, on the display screen of the display unit  26 , the chromatogram created by the signal processor  21 , so as to let a user of the waveform processing assistance system  1  specify the rising and falling points of the peak based on the two parameters “Width” and “Slope.” 
     One example of the display screen on which a peak waveform of a chromatogram is displayed is shown in  Fig. 3 . The display screen of the display unit  26  has a screen area  20  for showing a peak waveform of a chromatogram, with the horizontal axis indicating time and the vertical axis indicating the intensity. A mouse pointer  31  is displayed on the screen area  20  by a marker display processor  28  of the waveform analyzer  22 . The display screen in the present example shows the situation where the user has moved the mouse pointer  31  to a point P on the peak waveform and clicked the mouse to specify the rising point of the peak. 
     When the user moves the mouse pointer  31  to a point P on the peak waveform and clicks a button of the mouse, a slope information display processor  29  of the waveform analyzer  22  immediately calculates the value of the slope of the waveform at the point P specified by the user, based on the waveform data, and displays the calculated slope value (numerical value)  32  near the point P. The slope value (numerical value) may be displayed at a different position which is not near the point P yet easy to view, e.g. at the upper right corner of the screen. 
     In the present embodiment, a mouse is used as the input unit  25  and the rising point of the peak is specified when the mouse is clicked by the user. If the display unit  26  has a touchscreen, the point P on the waveform can be specified by touching the screen with a stylus pen or a finger of the user, or by a similar method. It is also possible to automatically select, as the specified point, the point on the peak waveform on which the mouse pointer  31  currently lies, without requiring the clicking or other special operation for the point specification. 
     If the position of the specified point is changed by the user, the waveform analyzer  22  immediately recalculates the slope value according to the change and updates the slope-related information with the new slope value  32  calculated for the new position. 
     Thus, the slope value  32  at the point specified by the user is displayed in real time as the slope-related information on the display screen on which the peak waveform is shown. Therefore, the user can intuitively determine the value of the parameter. 
     Based on the slope-related information thus displayed, the user determines the rising and falling points of the peak waveform. Then, based on the information of the specified rising and falling points of the peak waveform, the preparative separation time determiner  23  determines the point in time to begin or end the preparative separation by the fraction collector  16 , and sends control signals to a preparative separation controller  17 . The preparative separation controller  17  opens or closes an electromagnetic valve (preparative separation valve) of the fraction collector  16  according to the control signals so that the components in the eluate are separately and individually collected in different vial containers. Thus, the entire sequence of the process performed by the preparative liquid chromatograph is completed. 
     Second Embodiment 
     The second embodiment of the present invention is hereinafter described by means of  Fig. 4 , which shows one example of the display screen on which a peak waveform of a chromatogram is shown. The following description only deals with the operation of the waveform analyzer  22 , since the other operations are the same as in the first embodiment. 
     The display screen of the display unit  26  has a screen area  30  for showing a peak waveform of a chromatogram, with the horizontal axis indicating time and the vertical axis indicating the intensity. The display screen in the present example shows the situation where the user has specified a point P on the peak waveform as the rising point of the peak in the screen area  30 . 
     When a point P on the peak waveform is specified by the user, the slope information display processor  29  of the waveform analyzer  22  determines the slope of the waveform at the specified point P, calculates a tangent  33  to the curve at the point P, and displays the tangent on the screen. 
     If the position of the specified point is changed by the user, the slope information display processor  29  of the waveform analyzer  22  immediately recalculates the tangent according to the change and redisplays the tangent  33  at the new point as the slope-related information. Thus, the tangent  33  at the point specified by the user is displayed in real time as the slope-related information on the display screen on which the peak waveform is shown. Therefore, the user can intuitively determine the value of the parameter. 
     When the display range of the screen area  30  is changed as a result of some operation, such as the expanding of the vertical axis of the screen area  30 , the slope information display processor  29  of the waveform analyzer  22  immediately recalculates the position of the point P, the slope of the tangent at the point P and other relevant values, and redisplays the waveform and the tangent  33 . The operation of expanding (or contracting) the vertical axis on the display screen and redisplaying the waveform may be applied to the entire screen area  30  or only to a specific peak among a plurality of peaks displayed in a superposed form on the screen area  30 . The displayed information enables users to determine whether or not the rising and falling points of the peak in a spectrum is appropriate, even if the spectrum has a low peak intensity. This is convenient, for example, when a plurality of spectra which only differ from each other in peak intensity are shown in a superposed form on the screen area  30 . Since the values of the parameters necessary for the waveform processing can be quickly specified, the analysis time of the waveform processing can be shortened. 
     Third Embodiment 
     The third embodiment of the present invention is hereinafter described by means of  Fig. 5 , which shows one example of the display screen on which a peak waveform of a chromatogram is shown. The following description only deals with the operation of the waveform analyzer  22 , since the other operations are the same as in the first embodiment. 
     The display screen of the display unit  26  has a screen area  40  for showing a peak waveform of a chromatogram, with the horizontal axis indicating time and the vertical axis indicating the intensity. The display screen in the present example shows the situation where the user has specified a point P on the peak waveform as the rising point of the peak in the screen area  40 . 
     When a point P on the peak waveform is specified by the user, the slope information display processor  29  of the waveform analyzer  22  immediately calculates the tangent to the curve at the point P and displays the tangent on the screen. Furthermore, the processor  29  also displays a grid  34  including a set of grid lines parallel to the tangent and another set of grid lines each of which is symmetrical with the tangent with respect to the vertical axis. 
     If the position of the specified point is changed by the user, the slope information display processor  29  of the waveform analyzer  22  immediately recalculates the tangent according to the change and redisplays, as the slope-related information, the grid  34  parallel to and symmetrical with the tangent at the new point. Thus, the grid  34  parallel to the tangent to the waveform at the point specified by the user is displayed in real time as the slope-related information on the display screen on which the peak waveform is shown. Therefore, the user can intuitively determine the value of the parameter. 
     When the display range of the screen area  40  is changed as a result of some operation, such as the expanding of the vertical axis of the screen area  40 , the slope information display processor  29  of the waveform analyzer  22  immediately recalculates the slope of the grid lines and other relevant values, and redisplays the grid  34  on the screen area  40  according to the change of the display range. The displayed information enables users to determine whether or not the rising and falling points of the peak in a spectrum are appropriate, even if the spectrum has a low peak intensity. This is convenient, for example, when a plurality of spectra which only differ from each other in peak intensity are shown in a superposed form on the screen area  40 . Since the values of the parameters necessary for the waveform processing can be quickly specified, the analysis time of the waveform processing can be shortened. 
     In  Fig. 5 , the grid  34  includes a set of grid lines parallel to the tangent and another set of grid lines each of which is symmetrical with the tangent. As another example, the second set of grid lines may be orthogonal to the tangent. It is also possible to use only the grid lines parallel to the tangent. 
     The present invention is not limited to the case where one of the first through third embodiments is independently carried out, i.e. to the case where either the numerical value of the slope, the tangent or the grid is displayed as the slope-related information. The previously described embodiments can be combined; that is to say, it is possible to display two kinds of information selected from the group consisting of the numerical value of the slope, the tangent, and the grid, or to display all of the three kinds of information. 
     REFERENCE SIGNS LIST 
     
         
           1  . . . Waveform Processing Assistance System 
           20 ,  30 ,  40  . . . Screen Area 
           21  . . . Signal Processor 
           22  . . . Waveform Analyzer 
           23  . . . Preparative Separation Time Determiner 
           25  . . . Input Unit 
           26  . . . Display Unit 
           27  . . . Waveform Display Processor 
           28  . . . Marker Display Processor 
           29  . . . Slope Information Display Processor 
           31  . . . Mouse Pointer 
           32  . . . Slope Value 
           33  . . . Tangent 
           34  . . . Grid