JPH10300673A - Inductively coupled plasma emission spectrometer - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To enable high sensitivity and high precision analysis with an inductively coupled plasma spectrometer. An emission slit for measuring a background wavelength is provided at a place separated from an emission slit of a conventionally used spectroscope usually for measuring a background wavelength, and an emission slit for measuring a k emission intensity of a sample is provided behind the emission slit. By providing the detector, the signal intensity of the element and the signal intensity of the background wavelength can be measured simultaneously, and the measured signal intensity is corrected by the fluctuation of the signal intensity of the background wavelength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an inductively coupled plasma emission spectrometer.

[0002]

2. Description of the Related Art Conventional inductively coupled plasma optical emission spectrometers have a standard of signal intensity in the vicinity of a measurement wavelength in addition to an analysis wavelength of a target element in order to remove influences such as viscosity and matrix components of a sample. Measure the background wavelength. Conventional inductively coupled plasma emission analyzers have only a detector for the measurement wavelength as shown in FIG. 1, so that the background wavelength and the measurement wavelength cannot be measured simultaneously. The measurer was worried about the reliability of the measured values due to variations due to the measurement. As a high-sensitivity and high-precision analysis method, a spectrometer different from the spectrometer that measures the signal of the emission wavelength of the target element is used to remove variations due to the atomization efficiency of the atomizer and fluctuations due to plasma fluctuation. There is an internal standard measurement provided in the device. In this method, an internal standard element must be newly added to the measurement sample, and there is a possibility that a measurement error occurs due to a sampling error at the time of addition, an incorrect collection amount of a measurer, and the like. In general, the elements that can be selected as internal standard elements in the simultaneous internal standard measurement method are limited elements such as Y that are considered to be absolutely not contained in the sample, and the measurement wavelength is far apart from the element to be actually measured In many cases, there is a problem that the reliability is extremely low even when the reference intensity is measured at the same time. In addition, there is a simultaneous measurement method using a solid-state detector. However, it is very difficult with this method to find an array sensor suitable for a desired spectrophotometer to be designed. Further, since the size of each detector and the number of sensor elements are limited, it is very difficult to perform high-resolution measurement over a wide wavelength range with this device.

[0003] Further, a spectrometer called a polychromator, in which a plurality of detectors are installed in the same spectrometer, has been applied to an inductively coupled plasma emission spectrometer. It is used for analysis, and to measure the background wavelength, which is an important factor in emission analysis, must be measured separately by moving a mirror etc.Simultaneous sampling of the background wavelength and the measurement wavelength is performed. Did not.

[0004]

In the method according to the prior art shown in FIG. 1, first, an internal standard element must be added to a sample. Secondly, there is a problem that a spectroscope for measuring internal standard elements must be newly provided. In the method according to the prior art shown in FIG. 2, first, the number of array sensors is small and the wavelength range can be freely selected. Second, the size of the detector and the number of elements are limited, and the optical system used is limited. Third, inductively coupled plasma emission analysis has a problem that it becomes very expensive because there are so many near lines and a high-resolution detector is required.

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned problems of the prior art, to enable a signal near a measurement wavelength to be measured as a reference intensity, to remove noise components such as plasma fluctuations and sprayer fluctuations, and to simplify the operation. It is an object of the present invention to provide a high-precision, high-sensitivity inductively coupled plasma emission spectrometer.

[0006]

In order to achieve the above object, the present invention provides an inductively coupled plasma emission spectrometer according to the first aspect of the present invention, which includes a detector for measuring the intensity of a wavelength to be measured, as well as a detector for measuring the intensity of a wavelength to be measured. Provide a function that can measure the signal intensity at a wavelength different from the measurement wavelength of the target element by providing another detector, etc., or by providing a semiconductor detector that can simultaneously measure the signal intensity. When measuring the emission intensity of the target element, the fluctuation of the background intensity is always measured, and the target light emission intensity is corrected based on the degree of the fluctuation, thereby achieving the above object.

[0007] According to the above configuration, the inductively coupled plasma emission spectrometer can be provided without newly providing another spectroscope.
Not only can the optical system be designed freely, but also the simultaneous measurement of the measurement wavelength and the background wavelength can be performed at low cost, and high-sensitivity and high-accuracy analysis can be easily performed. Furthermore, since the measurement wavelength and the background wavelength of the target element can be measured simultaneously, the time required for integration is shortened, so that there is an advantage that the required sample amount is small.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 are explanatory views of an apparatus for explaining a conventional technique, and FIG. 3 is an explanatory view showing a configuration of an inductively coupled plasma emission spectrometer for applying the present invention. . 3 and 4 are explanatory diagrams of a sampling method and a correction method of the measurement signal.

As shown in FIG. 1, an inductively coupled plasma emission spectrometer of this embodiment includes a high frequency power supply 11 for generating a high frequency for lighting plasma, a light source 12 for actually lighting plasma, and the light source. Spectroscope 13 that disperses the light of the section using a dispersion element according to the wavelength, a detector 14 that detects the dispersed light, a wavelength driving device 15 that scans the light dispersion element, the high-frequency power supply section, a detection section, It is the same as the conventional device in having a control unit 16 for controlling the driving device.

As shown in FIG. 2, the conventional inductively coupled plasma emission spectrometer has only one exit slit / detector of a spectroscope for measurement. The wavelength must be moved to the wavelength set in the slit as the background, and the signal intensity and the background intensity cannot be measured simultaneously. Therefore, in the present invention, another exit slit is provided at the position of the measurement wavelength-the background setting wavelength from the conventional exit slit, and a detector is placed behind the exit slit so that the measurement wavelength and the background wavelength can be measured simultaneously. Further, a semiconductor detector or the like which can measure these two intensities simultaneously may be provided.

The luminous intensity Is of the target element and the luminous intensity Ib at the background wavelength fluctuate with time due to fluctuations of plasma as shown in FIG. Normally, the signal intensity in the inductively coupled plasma emission analysis is obtained by subtracting the integrated average value of the signal intensity at the background wavelength from the integrated value of the signal intensity measured for a predetermined time at the measurement wavelength of the target element. Used.

[0012]

(Equation 1)

In the conventional inductively coupled plasma emission analyzer, it is not possible to simultaneously sample at the measurement wavelength and the background wavelength of the target element, and to correct fluctuations due to non-periodic plasma fluctuations as shown in FIG. Could not. Therefore, the present invention corrects this fluctuation using Equation 2 or Equation 3.

[0014]

(Equation 2)

[0015]

(Equation 3)

According to equation (2), Is (t) is a function of the emission intensity of the target element shown in FIG.
Is a function of the emission intensity at background wavelength over time. It is considered that both behaviors within a certain period of time are almost the same as shown in FIG. 4 due to the influence of plasma fluctuation and the like.
For this reason, the influence of the noise component shown in FIG. 4 can be removed by calculating Is (t) / Ib (t) for each time lapse and calculating the integrated value as the measured value. However, when measuring a low-concentration sample, Is (t) and Ib (t) show almost the same number, and Is (t) / Ib (t) becomes infinitely close to 0, resulting in a large error. Become. Therefore, as shown in Expression 2, division is performed by a constant I 'in order to normalize Ib (t). It is considered appropriate to use the average value of Ib (t) in a certain section as I '. At this time, the initial value of Ib (t) may be set to I 'for convenience. As a result, the denominator of Equation 2 is as close as possible to 1, and the effect of the true noise component can be removed, so that high reliability can be obtained even in the measurement in the low density range. Further, as a method effective for the measurement of the low concentration region described above, the method of Expression 2 can be considered. Is (t) and Ib (t) are the same as in the case of Equation 2,
It is a function of the time of the emission intensity of the target element shown in FIG. 4 and the function of the time of the emission intensity at the background wavelength. In Equation 2, the noise component can be removed by integrating the value obtained by subtracting the intensity of the background wavelength from the intensity of the emission wavelength of the target element. Further, since the intensity of the measurement wavelength of the target element and the intensity of the background wavelength can be measured simultaneously, the time required for integration can be shortened as compared with the conventional case, as can be seen from FIGS. With these methods, noise components such as plasma fluctuations as shown in FIG. 3 can be corrected, and highly sensitive and accurate inductively coupled plasma emission analysis can be performed.

[0017]

According to the present invention, since the wavelength for elemental analysis and the background wavelength can be measured simultaneously, the signal intensity can be corrected in synchronization with the fluctuation of the background intensity. Thereby, highly accurate and reliable quantitative analysis can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of an inductively coupled plasma emission spectrometer for applying the present invention.

FIG. 2 is a schematic diagram illustrating a spectroscope section of a conventional inductively coupled plasma emission spectrometer.

FIG. 3 is a schematic view of a spectroscope section of an inductively coupled plasma emission spectrometer for explaining one embodiment of the present invention.

FIG. 4 is an explanatory diagram for explaining a signal intensity measuring method in a conventional inductively coupled plasma emission analysis.

FIG. 5 is an explanatory diagram for explaining a signal intensity measuring method in inductively coupled plasma optical emission analysis according to the present invention.

[Explanation of symbols]

21, 32: Detector, 22, 31, Slit, 23: Light dispersive element, 24: Mirror, 25, 26: Light split by the light dispersive element.

Claims (3)

[Claims] 1. An inductively coupled plasma emission spectrometer comprising a spectroscope using a light dispersion element and a control unit for controlling a wavelength driving device for scanning the light dispersion element, wherein the light dispersion element, slit, and mirror are provided. An inductively coupled plasma emission spectrometer characterized by comprising means capable of simultaneously measuring emission intensities at a plurality of wavelengths without moving or rotating elements such as a detector. 2. An inductively coupled plasma emission spectrometer according to claim 1, which has a function of sequentially correcting the signal intensity of the target element at the measurement wavelength with the emission intensity at the background intensity measurement wavelength for simultaneously measuring the emission intensity. . 3. An inductively coupled plasma emission spectrometer according to claim 2, wherein a semiconductor detector is used as a detector for measuring the emission intensity and background intensity of the target element at the measurement wavelength.