JP2014119368A - Spectrophotometer and program for spectral analysis - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spectrophotometer and a program for spectral analysis which are capable of preventing the increase of measurement time while suppressing noise generated in a spectrum.SOLUTION: A measurement condition in a wavelength region specified by a wavelength region specification processing unit 43 is changed to a measurement condition different from those in other wavelength regions, and a detector 14 is caused to scan in a baseline correction processing unit 41 and a sample measurement processing unit 42. Therefore, noise in a wavelength region where noise is apt to occur can be suppressed by reducing a scan speed of the detector 14 or fragmenting a sampling pitch only in, for example, the specific wavelength region. Consequently, the increase of measurement time can be prevented while suppressing noise generated in a spectrum.

Description

  The present invention provides a spectrophotometer capable of measuring a spectrum in at least the ultraviolet region and the visible region by irradiating a sample with light from a light source and irradiating the sample with light and scanning the light from the sample with a detector. And a program for spectroscopic analysis.

  For example, in a spectrophotometer such as an ultraviolet-visible spectrophotometer and an ultraviolet-visible near-infrared spectrophotometer, the light from the light source is dispersed by a spectroscope and irradiated on the sample, and the light from the sample is scanned by the detector. Thus, a spectrum such as a transmission spectrum or a reflection spectrum can be measured.

  Some types of spectrophotometers can scan with a detector in the absence of a sample and correct the baseline based on the received light energy data ( For example, see Patent Document 1 below). The spectrum measurement of the sample is executed in a state after the processing for correcting the baseline is performed. Thereby, the influence which the characteristic of each part, such as a light source, a spectroscope, and a detector provided in the spectrophotometer, has on a measurement result can be suppressed.

JP 2005-147811 A

  When measuring a sample using a spectrophotometer as described above, noise is likely to occur in the spectrum obtained by measurement in the ultraviolet region (for example, 190 to 300 nm) or the near infrared region (for example, 2000 nm or more). There was a problem. Further, in the case of a configuration in which the type of detector is switched depending on the wavelength, noise tends to be generated in the spectrum even in the detector switching region (for example, 800 to 1000 nm).

  Therefore, in order to suppress the influence of noise generated in the spectrum, it is conceivable to reduce the scanning speed by the detector or subdivide the sampling pitch. That is, if the scanning speed by the detector is slowed down, the number of integration increases, and if the sampling pitch is subdivided, the number of moving averages increases, so that noise generated in the spectrum can be reduced.

  However, when the scanning speed by the detector is slowed or the sampling pitch is subdivided, there is a problem that it takes time to measure the sample. In particular, when a plurality of samples are continuously measured, the time required for measurement of each sample becomes long, so that the measurement must be performed over a very long time as a whole.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a spectrophotometer and a program for spectroscopic analysis that can prevent the measurement time from becoming long while suppressing noise generated in the spectrum. And

  The spectrophotometer according to the present invention measures the spectrum in at least the ultraviolet region and the visible region by irradiating the sample with the light from the light source and irradiating the sample, and scanning the light from the sample with the detector. A baseline correction processing unit that scans the detector in the absence of a sample and performs processing for correcting the baseline based on the obtained received light energy data, and a baseline In a state after the processing for correcting the sample is performed, the sample measurement processing unit that performs processing for measuring the sample by scanning the light from the sample with the detector, and the sample without the sample Waves whose scanning conditions should be changed when scanning with the detector based on the received light energy data obtained by scanning the detector at a lower speed than during measurement. A wavelength region specifying processing unit for specifying a region, wherein the baseline correction processing unit and the sample measurement processing unit differ in measurement conditions in the wavelength region specified by the wavelength region specifying processing unit from other wavelength regions The detector is scanned by changing to measurement conditions.

  According to such a configuration, the measurement condition in the wavelength region specified by the wavelength region specification processing unit is changed to a measurement condition different from the other wavelength regions, and the detector in the baseline correction processing unit and the sample measurement processing unit Can be scanned. Accordingly, for example, only in a specific wavelength region, noise in a wavelength region where noise is likely to occur can be suppressed by slowing the scanning speed by the detector or subdividing the sampling pitch. Therefore, it is possible to prevent the measurement time from becoming long while suppressing noise generated in the spectrum.

  In particular, when performing processing for specifying the wavelength region whose measurement conditions should be changed, the received light energy data for a plurality of times is used for each wavelength obtained by scanning the detector at a lower speed than during sample measurement. Therefore, the wavelength region where noise is likely to occur can be specified with higher accuracy. Therefore, the noise generated in the spectrum can be more effectively suppressed by setting the wavelength region thus identified to be the wavelength region to be changed when the detector scans the wavelength region.

  The wavelength region specifying processing unit calculates ratio data by dividing the received energy data for a plurality of times for each wavelength obtained by scanning the detector at a low speed by the same wavelength, and the ratio data Based on this, the wavelength region for which the measurement condition when scanning with the detector should be changed may be specified.

  According to such a configuration, it is possible to more accurately identify a wavelength region in which noise is likely to occur, using ratio data calculated by dividing the received light energy data for a plurality of times for each wavelength by the same wavelength. . Therefore, noise generated in the spectrum can be more effectively suppressed by setting the measurement condition when the wavelength region is scanned by the detector to be the wavelength region to be changed.

  The wavelength region identification processing unit divides the ratio data into a plurality of groups according to wavelengths, performs principal component analysis for each group, identifies a wavelength region corresponding to a group with a lot of noise, and The measurement condition when scanning the region with the detector may be a wavelength region to be changed.

  According to such a configuration, by using principal component analysis, it is possible to specify a wavelength region corresponding to a group with a lot of noise more accurately. Therefore, noise generated in the spectrum can be more effectively suppressed by setting the measurement condition when the wavelength region is scanned by the detector to be the wavelength region to be changed.

  The spectroscopic analysis program according to the present invention measures a spectrum at least in the ultraviolet region and the visible region by irradiating a sample with light from a light source and irradiating the sample with light and scanning the light from the sample with a detector. A spectroscopic analysis program used in a spectrophotometer capable of scanning the detector without a sample and performing a process for correcting a baseline based on the received light energy data A sample measurement processing unit that performs processing for measuring a sample by scanning light from the sample with the detector in a state after processing for correcting the baseline is performed. And scanning the detector at a lower speed than when measuring the sample in the absence of the sample, and based on the received light energy data, the detector The computer functions as a wavelength region specifying processing unit that specifies a wavelength region in which measurement conditions for scanning should be changed, and the baseline correction processing unit and the sample measurement processing unit are specified by the wavelength region specifying processing unit. The measurement condition in the wavelength region is changed to a measurement condition different from the other wavelength regions, and the detector is scanned.

  According to the present invention, only the measurement conditions in the wavelength region where noise is likely to occur are changed to measurement conditions different from those in other wavelength regions, and the detector is scanned in the baseline correction processing unit and the sample measurement processing unit. Therefore, it is possible to prevent the measurement time from becoming long while suppressing noise generated in the spectrum.

It is the block diagram which showed the structural example of the spectrophotometer which concerns on one Embodiment of this invention. It is the flowchart which showed an example of the process by a control part. It is the figure which showed an example of the light reception energy data obtained when the wavelength area specific process part of a control part scans a detector at low speed.

  FIG. 1 is a block diagram showing a configuration example of a spectrophotometer according to an embodiment of the present invention. This spectrophotometer is, for example, an ultraviolet-visible spectrophotometer, and can measure spectra in the ultraviolet region and the visible region. However, the spectrophotometer to which the present invention is applied is not limited to the ultraviolet-visible spectrophotometer, and can measure at least the spectrum in the ultraviolet region and the visible region, such as an ultraviolet-visible near-infrared spectrophotometer. Such other spectrophotometers may be used.

  This spectrophotometer is provided with a measuring mechanism 1 including a light source 11, a spectroscope 12, a sample cell 13, a detector 14, and the like. In the measurement mechanism 1, the light from the light source 11 is dispersed by the spectroscope 12 and irradiated to the sample cell 13, and the light from the sample in the sample cell 13 is scanned by the detector 14, so that a transmission spectrum, a reflection spectrum, etc. Can be measured.

  As the light source 11, for example, a deuterium lamp or a halogen lamp can be used. The light from the light source 11 is split into light for each wavelength by a spectroscope 12 such as a diffraction grating, and is irradiated to the sample in the sample cell 13. Therefore, if the transmitted light from the sample in the sample cell 13 is scanned with the detector 14, the transmission spectrum can be measured, and if the reflected light is scanned with the detector 14, the reflected spectrum can be measured. Is possible.

  The detector 14 can be constituted by, for example, a photomultiplier tube or a PbS detector. In this example, the type of the detector 14 can be switched according to the wavelength, the spectrum in the short wavelength region is detected by the photomultiplier tube, and the spectrum in the long wavelength region is detected by the PbS detector. It comes to detect. In the ultraviolet-visible spectrophotometer having such a configuration, noise tends to be generated in the spectrum at two locations of the ultraviolet region (for example, 190 to 300 nm) and the switching region of the detector 14 (for example, 800 to 1000 nm). is there.

  In the detector 14, a signal corresponding to the received light energy is output. The output signal is amplified by the amplifier 2, converted into a digital signal by the A / D converter 3, and input to the control unit 4. The control unit 4 includes a CPU (Central Processing Unit), for example, and controls the operation of each unit such as the measurement mechanism 1 provided in the spectrophotometer. For example, an operation unit 5, a display unit 6, a storage unit 7, and the like are connected to the control unit 4.

  The operation unit 5 includes, for example, a keyboard or a mouse, and an operator can perform an input operation by operating the operation unit 5. The display unit 6 can be configured by a liquid crystal display, for example, and can display the result of the processing by the control unit 4 on the display unit 6. The storage unit 7 can be configured by, for example, a hard disk, a RAM (Random Access Memory), a ROM (Read Only Memory), and the like.

  The control unit 4 functions as various functional units such as a baseline correction processing unit 41, a sample measurement processing unit 42, and a wavelength region specifying processing unit 43, for example, when the CPU executes a program. The baseline correction processing unit 41 irradiates light from the light source 11 in a state where there is no sample in the sample cell 13 (for example, a state where only the solvent is present), and scans the detector 14 to obtain the received light reception energy data. Based on this, a process for correcting the baseline is performed. Since the processing for correcting such a baseline is a known technique, detailed description thereof will be omitted.

  The sample measurement processing unit 42 performs processing for measuring the sample by causing the detector 14 to scan light (for example, transmitted light or reflected light) from the sample in a state where the sample is in the sample cell 13. The process for measuring the sample is executed in a state after the process for correcting the baseline is performed. Thereby, the influence which the characteristic of each part, such as the light source 11, the spectroscope 12, and the detector 14 with which the spectrophotometer is provided, can suppress the measurement result. Since the processing for measuring such a sample is a known technique, a detailed description thereof will be omitted.

  The wavelength region identification processing unit 43 identifies the wavelength region whose measurement conditions for scanning with the detector 14 are to be changed. The specified wavelength region data (specific wavelength region data) is stored in the storage unit 7 and used in the processing by the baseline correction processing unit 41 and the sample measurement processing unit 42. That is, the baseline correction processing unit 41 and the sample measurement processing unit 42 change the measurement condition in the wavelength region specified by the wavelength region specification processing unit 43 to a measurement condition different from the other wavelength regions, and change the detector 14. It is supposed to be scanned. Hereinafter, an example of processing by the wavelength region specifying processing unit 43 will be specifically described.

  FIG. 2 is a flowchart showing an example of processing by the control unit 4. Measurement conditions such as a scanning speed, a sampling pitch, and a wavelength region when the detector 14 is scanned can be set in advance by an operator operating the operation unit 5. As described above, when the measurement condition is set by the operator's operation, the control unit 4 performs a process for storing the set measurement condition in the storage unit 7 (step S101).

  Thereafter, the wavelength region identification processing unit 43 of the control unit 4 causes the light source 11 to emit light in the absence of the sample, and scans the detector 14 (step S102). At this time, the sampling pitch, the wavelength region, and the like are set as measurement conditions set in advance, but the scan speed is made to scan the detector 14 at a lower speed than the preset scan speed. That is, the detector 14 is scanned at a lower speed than when measuring the sample (or correcting the baseline).

FIG. 3 is a diagram illustrating an example of received light energy data obtained when the wavelength region specifying processing unit 43 of the control unit 4 scans the detector 14 at a low speed. In this example, by reducing the scanning speed of the detector 14, light reception energy data for eight times can be obtained as the number of integrations. That is, by scanning a detector 14, receiving energy data _{E n} of 8 times for each wavelength (No.1~No.8) is adapted to obtain. In the present embodiment, the measurement time captures light energy data E _n obtained in this way as the energy curve of the cumulative number of times (8 times), which based on the received light energy data E _n, scanned by the detector 14 The wavelength region whose conditions are to be changed is specified.

Specifically, first, as shown in step S103 of FIG. 2, the ratio data is calculated based on the received light energy data E _n obtained. At this time, the light receiving energy data E _n of the accumulated number of times for each wavelength was obtained (8 times), for example by being substituted into the following formula is divided by the same wavelength each other for each wavelength, integrating the number of times for each wavelength The ratio data T _n for (eight times) is calculated. The ratio data T _n of each wavelength calculated in this way can be understood as a ratio curve for the number of times of integration (for 8 times).
T ₁ = (E ₁ / E ₂ ) × 100
T ₂ = (E ₂ / E ₃ ) × 100
T ₃ = (E ₃ / E ₄ ) × 100
T ₄ = (E ₄ / E ₅ ) × 100
T ₅ = (E ₅ / E ₆ ) × 100
T ₆ = (E ₆ / E ₇ ) × 100
T ₇ = (E ₇ / E ₈ ) × 100
T ₈ = (E ₈ / E ₁ ) × 100

Then, the accumulated number of times for each wavelength obtained as the ratio data T _n (8 times), is divided into a plurality of groups according to wavelength, principal component analysis is performed for each group (step S104). For example, if the wavelength region is set to 200 to 2000 nm when setting the measurement conditions in step S101, the wavelength region is set to 200 to 400 nm (first group), 400 to 600 nm (second group), and 600 to 800 nm (first). 3 group), 800-1000 nm (fourth group), 1000-1200 nm (fifth group), 1200-1400 nm (sixth group), 1400-1600 nm (seventh group), 1600-1800 nm (eighth group), 1800 It can be divided into 9 groups of ˜2000 nm (9th group).

The number of groups at the time of dividing into a plurality of groups in accordance with the ratio data T _n to the wavelength may be a predetermined value, even worker have a configuration can be set to any value Good. Moreover, the width of the wavelength region of each group does not need to be equal, and the wavelength region width may be different for each group.

When principal component analysis is performed for each group using the ratio data T _n of each group, eigenvalues of a plurality of principal components are obtained for each group using a known principal component analysis method. In this example, the eigenvalues lambda ₁ to [lambda] ₈ of the first to eighth main component is required is an integrated number of times (8 times), the ratio of the eigenvalues sum of the second to eighth principal component to the sum of their eigenvalues Is calculated by the following equation (step S105).
A value = (λ ₂ + λ ₃ + λ ₄ +... + Λ ₈ ) / (λ ₁ + λ ₂ + λ ₃ +... + Λ ₈ )

  In the present embodiment, the two groups are determined to be noisy groups in descending order of the A value calculated as described above. Then, the wavelength region corresponding to these two groups is specified as the wavelength region corresponding to the noisy group, and the wavelength region to be changed in the measurement condition when the detector 14 scans the wavelength region ( Step S106). The data of the wavelength region specified in this way is stored in the storage unit 7.

  Thereafter, when the process for correcting the baseline (step S107) or the process for measuring the sample (step S108) is performed, only the specified wavelength region is determined based on the measurement conditions set in step S101. Also, scanning is performed under special measurement conditions such as slowing the scanning speed of the detector 14 or subdividing the sampling pitch. On the other hand, for wavelength regions other than the specified wavelength region, the detector 14 is scanned under the measurement conditions set in step S101. In other words, during scanning by the detector 14, the measurement conditions change according to the wavelength region.

  As described above, in this embodiment, the measurement conditions in the wavelength region specified by the wavelength region specifying processing unit 43 are changed to measurement conditions different from those in other wavelength regions, and the baseline correction processing unit 41 and the sample measurement processing are changed. The detector 14 in the unit 42 can be scanned. Thereby, for example, only in a specific wavelength region, by reducing the scanning speed by the detector 14 or by subdividing the sampling pitch, noise in a wavelength region where noise is likely to occur can be suppressed. Therefore, it is possible to prevent the measurement time from becoming long while suppressing noise generated in the spectrum.

  In particular, when performing processing for specifying a wavelength region whose measurement conditions should be changed, received energy data for a plurality of times is obtained for each wavelength obtained by scanning the detector 14 at a lower speed than at the time of sample measurement. Since it can be used, a wavelength region in which noise is likely to occur can be specified with higher accuracy. Therefore, the noise generated in the spectrum can be more effectively suppressed by setting the wavelength region that is specified in this way to the wavelength region that should be changed when the detector 14 scans the wavelength region.

  Further, in the present embodiment, a wavelength region where noise is likely to occur can be identified with higher accuracy by using ratio data calculated by dividing received light energy data for a plurality of times for each wavelength by the same wavelength. Therefore, noise generated in the spectrum can be more effectively suppressed by setting the measurement condition when the wavelength region is scanned by the detector 14 to be changed.

  Furthermore, in the present embodiment, by using principal component analysis, it is possible to specify a wavelength region corresponding to a group with a lot of noise with higher accuracy. Therefore, noise generated in the spectrum can be more effectively suppressed by setting the measurement condition when the wavelength region is scanned by the detector 14 to be changed.

  In the above embodiment, the ultraviolet-visible spectrophotometer in which noise is likely to occur in the spectrum has been described in two places, the ultraviolet region (for example, 190 to 300 nm) and the switching region of the detector 14 (for example, 800 to 1000 nm). For this reason, a configuration has been described in which two wavelength regions are specified as wavelength regions in which noise is likely to occur. However, the configuration is not limited to such a configuration, and only one wavelength region or three or more wavelength regions in which noise is likely to occur is specified. Such a configuration may be adopted. For example, in the case of an ultraviolet-visible near-infrared spectrophotometer that easily generates noise in the near-infrared region (for example, 2000 nm or more) in addition to the above two wavelength regions, three wavelengths are likely to be generated in the ultraviolet-visible near-infrared spectrophotometer. The configuration may be such that the area is specified.

  Further, the processing for the wavelength region specifying processing unit 43 to specify the wavelength region is not limited to the processing as in the above embodiment. In other words, a configuration in which ratio data is calculated by dividing the received light energy data for a plurality of times by the same wavelength, or the ratio data is divided into a plurality of groups according to the wavelength, and a principal component analysis is performed for each group. It is possible to specify a wavelength region in which noise is likely to occur in all other modes, not limited to such a configuration.

  In the above embodiment, a so-called single beam type spectrophotometer has been described. However, the present invention can also be applied to a so-called double beam type spectrophotometer including a reference cell in addition to the sample cell 13.

  It is also possible to provide a program (spectrum analysis program) for causing a computer to function as the spectrophotometer as described above. In this case, the program may be provided in a state stored in a storage medium, or may be configured such that the program itself is provided.

DESCRIPTION OF SYMBOLS 1 Measurement mechanism 2 Amplifier 3 A / D converter 4 Control part 5 Operation part 6 Display part 7 Storage part 11 Light source 12 Spectroscope 13 Sample cell 14 Detector 41 Baseline correction process part 42 Sample measurement process part 43 Wavelength area specific process Part

Claims (4)

A spectrophotometer capable of measuring a spectrum in at least an ultraviolet region and a visible region by irradiating a sample with light from a light source and irradiating the sample with light and scanning the light from the sample with a detector,
A baseline correction processing unit that scans the detector in the absence of a sample and performs processing for correcting the baseline based on the obtained received light energy data;
A sample measurement processing unit that performs processing for measuring the sample by scanning light from the sample with the detector in a state after the processing for correcting the baseline is performed;
Wavelength region that specifies the wavelength region in which the detector should be scanned at a lower speed than when measuring the sample in the absence of the sample, and the measurement conditions for scanning with the detector should be changed based on the obtained received light energy data With a specific processing unit,
The baseline correction processing unit and the sample measurement processing unit change the measurement conditions in the wavelength region specified by the wavelength region specification processing unit to measurement conditions different from other wavelength regions, and scan the detector. A spectrophotometer characterized by that.   The wavelength region specifying processing unit calculates ratio data by dividing the received energy data for a plurality of times for each wavelength obtained by scanning the detector at a low speed by the same wavelength, and the ratio data 2. The spectrophotometer according to claim 1, wherein a wavelength region in which a measurement condition when scanning with the detector is to be changed is specified.   The wavelength region identification processing unit divides the ratio data into a plurality of groups according to wavelengths, performs principal component analysis for each group, identifies a wavelength region corresponding to a group with a lot of noise, and 3. The spectrophotometer according to claim 2, wherein a wavelength region to be changed is a measurement condition when the region is scanned by the detector. Spectroscopy used in a spectrophotometer that can measure the spectrum in at least the ultraviolet region and the visible region by irradiating the sample with light from the light source and irradiating the sample with the light, and scanning the light from the sample with the detector. An analysis program,
A baseline correction processing unit that scans the detector in the absence of a sample and performs processing for correcting the baseline based on the obtained received light energy data;
A sample measurement processing unit that performs processing for measuring the sample by scanning light from the sample with the detector in a state after the processing for correcting the baseline is performed;
Wavelength region that specifies the wavelength region in which the detector should be scanned at a lower speed than when measuring the sample in the absence of the sample, and the measurement conditions for scanning with the detector should be changed based on the obtained received light energy data Let the computer function as a specific processing unit,
The baseline correction processing unit and the sample measurement processing unit change the measurement conditions in the wavelength region specified by the wavelength region specification processing unit to measurement conditions different from other wavelength regions, and scan the detector. Spectral analysis program characterized by this.

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