JP3428417B2 - Chromatograph - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a chromatograph, and more particularly to a chromatograph designed to reduce noise by a moving average method of data.

[0002]

2. Description of the Related Art There are the following three methods for noise reduction in commonly used chromatographs.

The first is a method of reducing short cycle noise by providing an RC circuit composed of a coil and a capacitor in the output stage of the analog signal.

The second method is to obtain an output after converting an analog signal into a digital signal and performing exponential smoothing for noise reduction similar to the RC circuit.

Third, as shown in Japanese Patent Laid-Open No. 62-291562, after converting an analog signal into a digital signal, noise is reduced by a moving average method using a plurality of data points, and then an output is obtained. Is the way. The calculation formula used for the moving average is the Savitsuki-Golay formula.

[0006]

In the above-mentioned first and second techniques, when a circuit or a smoothing calculation formula that can obtain a large noise reduction effect is used, a necessary signal is also distorted and signal separation is deteriorated. Occur. Further, the signal height (peak height) is also reduced, and the original effect of improving the signal-to-noise ratio (hereinafter referred to as S / N ratio) cannot be obtained.

The third technique is to sample an analog signal at regular intervals and convert it into a digital signal, and for each sampling, average the digital signals at a predetermined number of sampling points before and after each sampling point. According to this, by increasing the number of data points used for moving average or lengthening the data interval (sampling interval), noise is reduced without distorting the necessary signal, and S / N is reduced. It is possible to improve the ratio.

However, this method causes a delay in the output signal with respect to the true signal. For example, data of sampling points having a sampling interval of 100 ms is 1
When a moving average is performed using one signal, the output signal causes a delay of 500 ms with respect to the true signal (described later). In particular, if the number of data points (the number of samplings) used for moving average is increased in order to obtain a large noise reduction effect, this delay also becomes large. If the noise reduction effect is changed frequently, the delay time from the true signal also changes frequently.

In the chromatograph, the retention time from the injection of the sample into the column until the component is eluted from the column and observed as a peak is used to identify the sample components. Therefore, the delay of data by the moving average method, in particular, the change of the delay time when the characteristics are changed causes a problem that accurate identification cannot be performed.

An object of the present invention is to provide a chromatograph capable of accurately identifying sample components even though the moving average method is used for noise reduction.

[0011]

To achieve the above object, the present invention provides a mobile phase to a column, injects a sample, separates the sample into components, and detects the separated components to detect an electrical signal. In the chromatograph, the moving average of the electric signal is generated, the electric signal is subjected to the moving average, and the data related to the chromatogram is obtained based on the averaged electric signal. It is characterized in that the start of the processing is delayed by the generation delay time of the electric signal.

According to this, since the holding time does not change due to the delay of the signal generation time due to the moving average,
The above-mentioned object of the present invention is achieved.

[0013]

1 shows an embodiment of a chromatograph according to the present invention. The solid line shows the flow of the mobile phase and the dotted line shows the flow of the signal. Further, FIG. 5 shows a time chart of input / output signals in each device.

The mobile phase eluent 1 is pressurized by a pump 2 and supplied to the column 4 at a constant flow rate. The sample is injected from the sample injection device 3, separated into each component in the column 4, and converted into an electric signal in the detection device 5. The output signal 6 from the detection device 5 is monitored by the data processing device 7, and the data processing device 7 relates to a so-called chromatogram, such as calculation of the chromatogram and the position and height of the peak of the chromatogram. The processing for obtaining the data thus obtained is executed. As a result, the component is identified by the peak position, that is, the time from the sample injection into the column 4 until the signal is detected (holding time), and the magnitude of the signal change amount observed as a peak (peak) is identified. The height can be used to quantify the components.

The above is a general chromatographic processing operation. In this embodiment, in addition to the above operation, the sample injection timing signal 8 from the sample injection device 3 is sent to the detection device 5 and based on this signal. The data processing start signal 9 delayed by the same time as the signal delay due to moving averaging which is the noise reduction filter processing performed in the detection device 5 is sent to the data processing device 7.

FIG. 2 shows a specific structure of the detection device 5 shown in FIG.

The detection device 5 includes a CPU 10, a memory 11,
The display device 12 displays the signal amount and the set conditions, and the input device 13 inputs the measurement conditions including the moving average condition (the number of data points to be averaged = the number of samplings).

The signal 14 indicating the change of the eluent (the absorbance signal when the absorption detector is used) is converted into the A / D converter 15
At a fixed time interval (here, 100 ms interval), data is collected (sampled) and converted into a digital signal. The digitized signal is subjected to noise reduction processing by the moving average method according to the moving average condition set by the CPU 10 from the input device 13.

The setting of the moving average condition with the input device 13 is as follows.
The time width of the data used in the processing of the moving average method (hereinafter,
Response time). For example, when the response time is set to "1 second", the sampling interval is 100 ms. Therefore, when the response data is set to 11 points, which is the number of data points of 5 points before and after the current data, and "2 seconds", the same applies. 21 points,
When "4 seconds" is set, 41-point data is used as data used in the processing of the moving average method.

Then, the processed data is converted into an analog signal by the D / A converter 16 and sent to the data processing device 7 as the output signal 6. At this time, output signal 6
Compared with the data input from the A / D converter 15 to the CPU 10, the data indicated by has a delay time corresponding to the noise reduction processing (see FIG. 5). For example, when the response time is set to "1 second", 5 points each before and after the current data (5 sampling points)
Therefore, a delay time of 5 points (500 ms) in the latter half is generated. Generally, the longer the response time, the greater the noise removal effect,
In proportion to this, the delay time of the output signal 6 increases.

Table 1 shows that the response time is set to "1 second".
Input signal (digital input signal to the CPU 10 after A / D conversion) and C after noise reduction processing
3 is a table showing output signals from the PU 10.

[0022]

[Table 1]

In order to obtain the data for 1 second, as described above, in the case of the sampling time interval of 100 ms, the input signal of 11 points in total, that is, 5 points before and after the input of the data to be averaged is used as a reference. Are averaged and output. That is, when the time T _n is used as a reference, the input signals (D _n-5 to D _{n + 5} ) at 11 points from the sampling time T _n-5 to T _{n + 5} are added, and further, at “11”. The division results in the output signal O _n . By this process,
The noise value is theoretically reduced to 1 / square root of 11 because the data of 11 points is averaged by addition and then divided by "11".

In this case, between the input signal D _n and the output signal O _n , as shown in Table 1, 5 points (500 ms) are required.
Signal delay time occurs. Similarly, when the response setting time is "2 seconds", there is a delay of 1 second, which is a time corresponding to 10 points, and when the response setting time is "4 seconds", there is a delay of 2 seconds which is a time corresponding to 20 points. Therefore, when the output signal 6 including the delay time is received by the data processing device 7 as it is and the processing for obtaining the data related to the chromatogram is performed, the data whose holding time is increased by the delay time is output. Therefore, the identification of sample components will be hindered.
(According to the time chart of FIG. 5, the processing start time of the data processing device 7 is the start time shown by the broken line.) Therefore, in this embodiment, the sample injection device 3 is caused to generate the sample injection timing signal 8. Means for outputting the sample injection timing signal 8 to the detection device 5 in response to the sample injection. Then, when the sample injection timing signal 8 is input to the detection device 5, based on the input of this signal, the data collection processing start signal 9 is provided at intervals of the delay time calculated from the preset response time. The data collection processing start signal 9 is output to the data processing device 7 together with the output signal 6.

In the data processor 7, the output signal 6 is made valid only when the data collection processing start signal 9 is input, and the processing of the data relating to the chromatogram is started. (According to the time chart of FIG. 5, the processing start time of the data processing device 7 is the start time shown by the solid line.) The delay interval between the output timing of the data collection processing start signal 9 and the sample injection timing signal 8 is , It is uniquely determined if the sampling interval and the number of samples (response time) are known. (In this embodiment, the sampling interval is 100 ms.
Therefore, if the response time is 1 second, 500 ms,
When the response time is 2 seconds, it is 1 second, and when the response time is 4 seconds, it is 2 seconds. Therefore, even if the setting of the response time is frequently changed to adjust the noise reduction effect, the detection device 5 automatically detects the data collection processing start signal 9 based on the delay time that is uniquely determined. Since the output timing can be changed, the data processing device 7 can always create a chromatogram with no delay in retention time.

FIG. 3 shows another embodiment of the chromatograph according to the present invention.

In FIG. 3, the solid line shows the flow of the mobile phase and the dotted line shows the flow of the signal, as in FIG. In this embodiment, the controller 2 that controls the detection device 5, the pump 2, and the like.
0 is provided. The response time of the detector 5 is
Set as one of the measurement conditions from the controller 20,
The condition setting signal 21 is sent to the detection device 5. When the sample injection timing signal 8 is input to the controller 20 from the sample injection device 3, the controller 20 synchronously outputs the gradient start signal 25 to the pump 2. The data collection processing start signal 9 is output with a delay time corresponding to the response time set from the input of the sample injection timing signal 8 as in the above-described embodiment.

Also in this embodiment, the holding time in the data processing device 7 does not always change even if the setting of the response time is frequently changed in order to adjust the noise reduction effect. Furthermore, in the present embodiment, it is possible to simultaneously handle a signal to be synchronized with sample injection (at the start of gradient elution, etc.), which is effective when the composition of the mobile phase is changed during analysis.

FIG. 4 shows a chromatogram obtained by the example of the present invention in comparison with that by the conventional example.

The chromatogram 22 is a chromatogram when no noise reduction processing is performed. The chromatogram 23 is a case where the noise reduction process by the moving average method is applied to the chromatogram 22 but the process of the present invention is not performed. Although the noise is reduced in the chromatogram 23, the peak position is different from that in the chromatogram 22, and the retention time is shifted overall. On the other hand, the chromatogram when the present invention is carried out is the chromatogram 24. In the chromatogram 24, noise is reduced, and the chromatogram in which the peak positions are the same as those of the chromatogram 22 is obtained.

[0031]

As described above, according to the present invention, it is possible to realize a chromatograph whose retention time does not change even if the moving average method is used for noise reduction. Further, even when the noise reduction effect is changed, it is possible to realize a chromatograph in which the retention time is not always delayed.

Therefore, it is possible to provide a chromatograph capable of accurately identifying sample components even though the moving average method is used for noise reduction.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an example of a chromatograph according to the present invention.

FIG. 2 is a specific configuration diagram of the detection device of FIG.

FIG. 3 is a conceptual diagram of another embodiment of the chromatograph according to the present invention.

FIG. 4 is a diagram showing a chromatogram obtained according to an example of the present invention in comparison with that according to a conventional example.

FIG. 5 is a time chart of the chromatograph of the present invention.

[Explanation of symbols]

1: Eluent (mobile phase), 2: Pump, 3: Sample injection device, 4: Column, 5: Detection device, 6: Output signal from detection device, 7: Data processing device, 8: Sample injection (timing) Signal, 9: data processing start signal.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 62-291562 (JP, A) JP 1-126545 (JP, A) JP 60-253972 (JP, A) JP 60- 205362 (JP, A) JP 60-113151 (JP, A) JP 62-32360 (JP, A) JP 52-115294 (JP, A) JP 3-29850 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01N 30/86

Claims (7)

(57) [Claims] 1. A mobile phase is supplied to a column, a sample is injected, the sample is separated into components, an electric signal is generated by detecting the separated components, and the electric signal is moving averaged. In a chromatograph which executes a process for obtaining data related to a chromatogram based on the averaged electric signal, the process is performed for a time corresponding to the generation delay time of the averaged electric signal generated by the moving averaging. A chromatograph characterized by being configured to delay the start. 2. A column and a pump for supplying the mobile phase to the column, a sample injection means for injecting a sample <br/> the mobile phase which is fed by the pump, separated by the column component the has a detection means for detecting, and data processing means for generating a chromatogram by averaging the output signal of the multiple based on output <br/> force signal of the detecting means or, et al., the detection means The detected component signal to the specified sample
Sampling at the sampling interval and the sampled signal
The moving average processing is performed based on the preset conditions, and the
Output to the data processing means and based on the moving average processing
Transmitting data processing start signal after a delay time to said data processing means, said data processing means, the de - chromatograph is characterized in that so as to perform the chromatogram creation processing based on data processing start signal . 3. The chromatograph according to claim 2, wherein the detecting means includes setting means for setting the averaging condition. 4. A column, a pump for supplying the mobile phase to the column, a sample injection means for injecting a sample <br/> the mobile phase which is fed by the pump, separated by the column component the a detection means for detecting a data processing means for creating a person detecting means whether we give et <br/> chromatogram based on the output signal, and a controller for controlling each device, said detecting means The detected component signal at a predetermined interval.
And sampling, moving with sampled signals Rights
Outputs the detection signal after equalization processing to the data processing means
Then, when the sample injection means starts sample injection, the controller transmits a data processing start signal to the data processing means based on a delay time corresponding to the number of sampling data points used for the moving average processing. and, wherein the data processing means, the de - chromatograph is characterized in that so as to perform a chromatogram creation processing based on data processing start signal. 5. The chromatograph according to claim 4, wherein the controller is provided with setting means for setting conditions of the moving average processing . 6. The condition set by the setting means is
The chromatograph according to claim 3 or 5 , wherein the chromatograph is a time width of data used for the moving average processing. 7. A mobile phase is sent to a column, a sample is injected into the sent mobile phase, the solution eluted from the column is detected and converted into a signal, and the signal is collected. In the analysis method for creating a chromatograph, the detected signal is sampled and a predetermined number of samples are sampled.
Performs moving average processing with the ring signal, the moving average processing from the timing of performing the sample injection
Analysis method and performing work <br/> configuration of chromatograms with a delay time due to be performed.