JP4600228B2 - ICP emission spectroscopic analysis method and ICP emission spectroscopic analysis apparatus - Google Patents

Description

  The present invention relates to an inductively coupled plasma (ICP) emission spectroscopic analysis method and an ICP emission spectroscopic analysis apparatus.

  In an ICP emission spectroscopic analyzer, a sample solution sprayed by a nebulizer or the like is introduced into a high-temperature high-frequency plasma in an ICP torch, excited and emitted, and the emitted light is wavelength-dispersed by a spectrometer and detected by a detector. An emission spectrum is acquired, and a qualitative analysis of the element contained in the sample liquid is performed from the wavelength of the spectrum line appearing in the emission spectrum, and a quantitative analysis of the element is performed from the intensity of the spectrum line (see Patent Document 1, etc.).

  In such an ICP emission spectroscopic analyzer, due to the difference in the configuration of the optical system, it is roughly divided into a sequential type configuration that sequentially detects spectral lines of different wavelengths by rotating a monochromator, and a detection in which a large number of micro light receiving elements are arranged, for example. There is a multi-channel configuration in which a number of spectral lines are detected simultaneously using a detector. The multi-channel type apparatus has an advantage that a large number of spectral lines can be acquired in a short time, but on the other hand, the wavelength accuracy is determined by the size of one light receiving element of the detector, etc. There is a problem that it is difficult to increase the wavelength accuracy compared to the above.

  By the way, there are various factors that cause an error in quantitative analysis in ICP emission spectroscopic analysis, and main factors include physical interference and ionization interference. Physical interference is a phenomenon in which the physical properties such as the viscosity and volatility of the solution change due to the influence of components other than the target component contained in the sample, and the transportation and spraying conditions of the sample change. In addition, ionization interference is a phenomenon in which ionization efficiency of a target element decreases due to the influence of ionization of such an element when elements that are particularly easily ionized such as sodium (Na) and potassium (K) coexist.

  Therefore, if the presence or absence of such interference and the extent of the impact can be appropriately evaluated, the reliability of the quantitative value obtained by the analysis can be judged, and the quantitative value can be corrected as necessary. Is possible. However, no method has been proposed in the past for simply evaluating the presence or degree of influence of physical interference or ionization interference for various types of analysis target elements.

  For example, conventionally, an ICP emission spectroscopic analyzer having a function of monitoring the emission intensity of argon (Ar) used for plasma generation is known. In principle, such an apparatus changes the emission intensity of Ar. May detect a change in the state of sample introduction. However, since the emission intensity of Ar is actually very strong, even if there is physical interference or ionization interference as described above, there is no clear change in the emission intensity so that the influence can be observed. Therefore, it is almost impossible to evaluate the influence of physical interference, ionization interference and the like from the change in emission intensity of Ar.

  An addition recovery test is well known as an accurate evaluation method of the influence of interference. Addition recovery test is an analysis of a sample to be analyzed and a sample to which a certain amount of a pure product (standard sample) of a target component with a known concentration is added, and comparing the analysis results of both, This is a method for evaluating the quantification accuracy by determining whether or not it is accurately quantified. However, in order to perform the addition recovery test, it is necessary to prepare a standard sample, and it is necessary to prepare a standard sample for all target elements to be analyzed, which is very troublesome. Therefore, it is not practical especially when performing multi-element simultaneous analysis.

  Furthermore, there is also known an ICP emission spectroscopic analyzer having a function of simultaneously displaying the concentration (semi-quantitative value) of main component elements when displaying the result of qualitative analysis. It is possible to know whether such coexisting elements are included. However, this can only be estimated whether there is a possibility of physical interference or ionization interference depending on the type of coexisting elements, and is not very useful in determining the influence of interference and evaluating the degree of influence.

Japanese Patent Laid-Open No. 10-253540

  The present invention has been made to solve the above-mentioned problems, and the object of the present invention is to simply evaluate the presence and extent of influences such as physical interference and ionization interference for various types of analysis target elements. The present invention provides an ICP emission spectroscopic analyzer capable of performing the above.

In order to solve the above problems, the first invention is to introduce a mist-like sample liquid into a high-frequency plasma to excite components in the sample and emit light having a wavelength unique to each element. In the ICP emission spectroscopic analysis method for quantitative analysis of the element based on the emission spectrum obtained by spectroscopic measurement of the light,
By introducing the atomized sample liquid into the high-frequency plasma, the components in the sample are excited to emit light having a wavelength that is unique to each element, and based on the emission spectrum obtained by spectroscopic measurement of the light. In the ICP emission spectroscopic analysis method for quantitative analysis of the elements,
For each of a plurality of various elements, a combination of a neutral atomic beam and an ion beam for each element and reference intensity information of those bright lines are stored in a storage means,
based rather by qualitative analysis in emission spectrum obtained by measuring a) target sample, if any of the elements that are stored in the storage unit is determined to be included in the said purpose the sample, the A first step of calculating the intensity ratio by obtaining the intensity of each of the neutral atomic beam and ion beam derived from the specific element from the emission spectrum ;
b) Measuring a standard sample to obtain an emission spectrum , and when the specific element is contained in the standard sample, each of a neutral atomic beam and an ion beam corresponding to the combination derived from the specific element While calculating the intensity ratio from the emission spectrum and calculating the intensity ratio, if the standard element does not contain the specific element, neutrality corresponding to the combination derived from another element different from the specific element After obtaining the intensity of each of the atomic beam and the ion beam from the emission spectrum, using the intensity and the reference intensity information stored in the storage means, the neutral atomic beam derived from the specific element and the ion beam A second step of estimating the intensity ratio;
c) Based on the difference between the intensity ratio calculated in the first step and the intensity ratio calculated or estimated in the second step, for evaluating the influence of physical interference and ionization interference during measurement of the target sample. A third step of generating information;
It is characterized by performing.

A second invention made to solve the above-mentioned problems is an apparatus that embodies the ICP emission spectroscopic analysis method according to the first invention, wherein the atomized sample liquid is introduced into the high-frequency plasma. In an ICP emission spectroscopic analysis apparatus that excites components in a sample to emit light having a wavelength unique to each element, and performs quantitative analysis of the element based on an emission spectrum obtained by spectroscopic measurement of the light ,
a storage means for holding a reference intensity information combinations and their emission lines of neutral atomic beams and ion beams to about it based Motogoto to a) a plurality of various elements,
b) Obtaining an emission spectrum for the target sample, and when it is determined by qualitative analysis based on the emission spectrum that any element stored in the storage means is included in the target sample, the specific element First intensity ratio calculation means for calculating the intensity ratio by obtaining the intensity of each of the neutral atomic beam and the ion beam corresponding to the combination derived from the emission spectrum ;
c) to obtain the emission spectrum for the standard sample, the when the standard specimen contains a pre Kitoku constant elements, each of the neutral atomic beam and ion beam corresponding to the combination from that particular element intensity one to calculate the strength of ratios determined from the emission spectrum, in the case does not contain the specific elements in the standard sample, corresponding to the combination from another element which is different from its specific element Neutral intensity beams and ion beams derived from the specific element using the intensity and reference intensity information stored in the storage means after obtaining the intensity of each of the atomic atomic beam and the ion beam from the emission spectrum Second intensity ratio calculating means for estimating the intensity ratio of
d) Physical interference during measurement of the target sample based on the difference between the intensity ratio calculated by the first intensity ratio calculating means and the intensity ratio calculated or estimated by the second intensity ratio calculating means. And evaluation information generating means for generating information for evaluating the influence of ionization interference,
It is characterized by having.

  In ICP emission spectroscopic analysis, multiple emission lines with different wavelengths are emitted from the same element. However, with the exception of some elements such as alkali metals, neutral emission lines and ion lines exist in the emission lines, resulting in physical interference. In addition, the influence of ionization interference is different between neutral atomic beams and ion beams. Therefore, in the ICP emission spectroscopic analysis apparatus according to the second invention that embodies the ICP emission spectroscopic analysis method according to the first invention, the first intensity ratio calculation means measures a target sample containing an unknown element to be analyzed. The emission spectrum is obtained, and the intensity of the neutral atomic beam and ion beam derived from any element (specific element) stored in the storage means among the bright lines appearing in the emission spectrum is obtained. The intensity ratio is calculated. On the other hand, the second intensity ratio calculation means obtains an emission spectrum by measuring a standard sample in the same manner as for the target sample, and when the standard sample contains the specific element, it is derived from the specific element. The ratio of the intensity of the neutral atomic beam to the ion beam is calculated.

  In this case, since the specific element used for evaluation and the wavelength of the emission line are the same for the target sample and the standard sample, the intensity ratio between the two is the ideal state without physical interference or ionization interference. It should be the same. In other words, since the difference in intensity ratio between the two reflects the degree of influence such as physical interference and ionization interference, the evaluation information generating means evaluates the presence / absence of the interference and the degree of interference based on this difference. Information can be created.

  However, since it is not realistic to create a standard sample for all the elements to be analyzed, as described above, “the specific element from which the intensity ratio is obtained by the first intensity ratio calculating means is included in the standard sample. In many cases, the element contained in the standard sample is different from the element contained in the target sample.

Therefore, by ICP emission spectrometer according to ICP emission spectroscopic analysis method and the second invention according to the first invention, the front term memory unit, they emission line with a combination of a neutral atom beam and ion beam for a plurality of elements The second intensity ratio calculation means that retains the reference intensity information and executes the second step includes a specific element from which the first intensity ratio calculation means obtains the intensity ratio in the standard sample. If not, its a specific element stored in the memory means with those intensities on obtained from each emission spectrum intensity of a neutral atomic beam and ion beam corresponding to the combination from different other elements strength using the reference intensity information to estimate the intensity of the ratio of the neutral atomic beams and ion beams derived from the specific elements, said evaluation information generating means for performing a third step in which this estimate are Using the said first intensity ratio calculation means with the obtained intensity ratio, generates information for assessing the impact of physical interference and ionization interference during measurement of the target sample.

This eliminates the need to create a standard sample for every element to be analyzed, so that the effects of physical interference and ionization interference can be easily evaluated.

  According to the ICP emission spectroscopic analysis method according to the first invention and the ICP emission spectroscopic analysis apparatus according to the second invention, the presence / absence and the extent of the influence such as physical interference and ionization interference that could not be properly evaluated conventionally. Therefore, by using this, for example, the reliability of the quantitative value that is the result of quantitative analysis can be judged, or the quantitative value can be corrected appropriately. In addition, since it is not necessary to prepare standard samples for all of the target elements when performing such an evaluation, it is possible to reduce the labor for preparing the standard samples and perform the evaluation easily.

An embodiment of an ICP emission spectroscopic analysis apparatus according to the second invention for performing the ICP emission spectroscopic analysis method according to the first invention will be described below with reference to FIGS.
FIG. 1 is a schematic configuration diagram of an ICP emission spectroscopic analyzer according to this embodiment. This ICP emission spectroscopic analyzer is a multi-channel type apparatus.

  In FIG. 1, the sample solution supplied from the autosampler 11 controlled by the control unit 21 is atomized by a nebulizer (not shown) and then introduced into the light emitting unit 10 and excited by a high-temperature plasma flame. The light generated thereby is collected by the condenser lens 12, passes through the slit 13, and is sent to the diffraction grating 14. The light wavelength-dispersed by the diffraction grating 14 is detected almost simultaneously by a multi-channel detector 15 such as a linear CCD sensor. Specifically, here, the light between the wavelengths λ1 and λ2 reaching the both ends of the light receiving surface of the detector 15 is detected almost simultaneously, and the detection signal photoelectrically converted by each light receiving element is sent to the data processing unit 20. send. Therefore, the wavelength resolution depends on the number of light receiving elements of the multichannel detector 15.

  The data processing unit 20 converts the detection signal into digital data (spectral data) and performs arithmetic processing according to a predetermined algorithm, thereby executing qualitative analysis and quantitative analysis of the sample. The operations of the above-described units are comprehensively controlled by the control unit 21, and many of the functions of the control unit 21 and the data processing unit 20 are achieved by executing predetermined programs on a general-purpose personal computer 22. The personal computer 22 is connected to an input unit 23 including a keyboard for an operator to input analysis conditions and the like, and a display unit 24 including a display for displaying measurement results and the like.

  In the ICP emission spectroscopic analysis apparatus having the above configuration, when ICP spectroscopic analysis is performed on a certain sample, the data processing unit 20 generates an emission spectrum in the wavelength range of λ1 to λ2 as shown in FIG. Created. As described above, in the present multi-channel apparatus, such a spectrum can be acquired in a much shorter time than in a sequential apparatus.

  The ICP emission spectroscopic analyzer of the present embodiment has a function of evaluating the degree of influence of physical interference and ionization interference as one index for evaluating the reliability of the quantitative analysis described above, and realizes such a function. In order to do so, the data processing unit 20 includes an interference evaluation database 202 and an evaluation processing unit 201 that executes processing using the same.

  In the interference evaluation database 202, the combination information of the wavelength of the neutral atom beam and the wavelength of the ion beam, and each wavelength for various elements having both the neutral atom beam and the ion beam with almost the same measurement sensitivity. Each strength reference data is stored in a database so that it can be easily searched. However, “substantially the same measurement sensitivity” here refers to, for example, a range of difference up to about 10 times as the same measurement sensitivity.

  Examples of the elements under the above conditions are, for example, silver (Ag), gold (Au), beryllium (Be), calcium, except for alkali metals that are easy to ionize and hardly generate neutral atomic beams. (Ca), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), indium (In), magnesium (Mg), manganese (Mn), nickel (Ni), lead (Pb), palladium (Pd), platinum (Pt), rhenium (Re), rhodium (Rh), ruthenium (Ru), tin (Sn), strontium (Sr), thallium (Tl), zinc (Zn), and the like. FIG. 3 shows an example of the contents of the interference evaluation database. (A) shows a combination of wavelengths of neutral atomic beams and ion beams of Ag and Au, and (b) shows reference intensity data for each wavelength of Ag. . In FIG. 3 (a), there are two pairs of Ag and three pairs of Au because there are a pair of neutral atomic beams and ion beams arranged side by side.

  Next, the operation of the interference evaluation process executed mainly by the evaluation processing unit 201 will be described with reference to the flowchart of FIG.

  First, an analyst prepares a standard sample containing any element described in the interference evaluation database 202, and instructs the input unit 23 to perform analysis on the standard sample. Upon receiving this instruction, the control unit 21 executes ICP emission spectroscopic analysis on the standard sample. As a result, the data processor 20 acquires the emission spectrum P1 in the wavelength range of λ1 to λ2 (step S1). Next, the control unit 21 performs ICP emission spectral analysis on the target sample. As a result, the data processor 20 acquires the emission spectrum P2 in the wavelength range of λ1 to λ2 (step S2).

  Next, the evaluation processing unit 201 performs a qualitative analysis based on the emission spectrum P2 of the target sample, and determines whether any element described in the interference evaluation database 202 is included (step S3). ). If the target sample does not include a plurality of elements described in the interference evaluation database 202, the evaluation to be performed here cannot be performed (step S14), and the process proceeds to step S13 as it is and the evaluation is not possible. The evaluation result is output to the display unit 24.

  When the target sample includes any element described in the interference evaluation database 202 (herein, the element is referred to as a specific element), the evaluation processing unit 201 includes the element described in the interference evaluation database 202. With reference to the wavelength of the combination of the neutral atomic beam and the ion beam due to the specific element, the intensity of the neutral atom beam and the ion beam is obtained on the emission spectrum P2. For example, as shown in FIGS. 4A and 4B, when a neutral atomic beam exists at the wavelength λa and an ion beam exists at the wavelength λb, the intensity of the neutral atomic beam is In and the intensity of the ion beam is Ii. become. Then, a ratio T1 between the intensity of the neutral atomic beam and the intensity of the ion beam is calculated (step S4).

  Next, it is determined whether or not the standard sample contains the specific element (step S5). When the standard sample includes the specific element, it is possible to compare the standard sample and the target sample with the same specific element. Therefore, the evaluation processing unit 201 uses the same wavelength of the combination of the neutral atom beam and the ion beam as used in calculating the intensity ratio between the neutral atom beam and the ion beam for the target sample as described above, and the emission spectrum. The intensity of the neutral atomic beam and ion beam is obtained on P1. Then, a ratio T2 between the intensity of the neutral atomic beam and the intensity of the ion beam is calculated (step S6).

  Under ideal conditions where there is no influence of physical interference or ionization interference, the intensity ratios T1 and T2 should be the same. Therefore, the evaluation processing unit 201 obtains a difference between the intensity ratios T1 and T2, and evaluates the degree of physical interference and ionization interference based on the difference, for example, by numerical values (step S7). However, in consideration of variations in analysis conditions and the like, even if there is no physical interference or ionization interference, there is a possibility that a slight difference may occur between the intensity ratios T1 and T2. Therefore, in consideration of such factors, for example, when the difference between the intensity ratios T1 and T2 is within a predetermined allowable value, the influence of interference is zero, and a difference that exceeds the allowable value occurs. In addition, the influence of interference may be calculated according to the difference. Of course, instead of numerical values, the presence / absence of the influence of interference may be simply output or may be expressed by the extent of the influence of interference being large, medium, or small. And the evaluation result produced | generated in this way is output to the display part 24 (step S13).

On the other hand, if it is determined in step S5 that the standard sample does not contain the specific element, the standard sample and the target sample cannot be compared with the same specific element. That is, since the wavelength of the element type and emission lines to be compared are different, simply can not be compared the intensity ratio of the two as in step S 6, S7. Therefore, the evaluation processing unit 201 obtains the intensity of neutral atomic beams and ion beams derived from appropriate elements (referred to as selective elements) on the emission spectrum P1 of the standard sample, and then performs interference evaluation. The intensity is standardized using the reference intensity data described in the database 202 for use. Then, the ratio T2 ′ is calculated from the standardized intensity for the neutral atomic beam and the ion beam (steps S9 and S10 ).

  The basic concept of standardization here is as follows. For example, it is assumed that the reference intensity for a neutral atom beam and an ion beam of a specific element in a target sample is neutral atom beam: ion beam = 10: 1, while neutral atoms of a selected element in a standard sample. It is assumed that the reference intensity for the line and the ion beam is neutral atomic beam: ion beam = 1: 10. In this case, when comparing the specific element in the target sample with the selected element in the standard sample, the intensity of the ion beam of the selected element is multiplied by 100 (or the intensity of the neutral atomic beam is divided by 100). The intensity ratio may be calculated above.

  For standardization using the reference strength as described above, it is desirable that the accuracy of the reference strength is higher. For this purpose, for example, a qualitative database calibration (correction of semi-quantitative information) as proposed by the present applicant in Japanese Patent Application No. 2005-142214 (filed on May 16, 2005) is used. Can do.

  In addition, the said Example is an example of this invention, and it is natural that even if it changes, corrects and adds suitably in the range of the meaning of this invention, it is included by this invention. For example, in the above embodiment, a multi-channel type ICP emission spectroscopic analyzer is shown, but the present invention can also be applied to a sequential type ICP emission spectroscopic analyzer. However, it goes without saying that the former is preferable in terms of analysis time.

1 is a schematic configuration diagram of an ICP emission spectroscopic analyzer that is one embodiment of the present invention. FIG. The figure which shows an example of the emission spectrum acquired with an ICP emission-spectral-analysis apparatus. The figure which shows an example of the content of the database for interference evaluation in the ICP emission-spectral-analysis apparatus of a present Example. Explanatory drawing of the interference evaluation process in the ICP emission-spectral-analysis apparatus of a present Example. The flowchart which shows the procedure of the interference evaluation process in the ICP emission-spectral-analysis apparatus of a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Light emission part 11 ... Autosampler 12 ... Condensing lens 13 ... Slit 14 ... Diffraction grating 15 ... Multichannel type detector 20 ... Data processing part 201 ... Evaluation processing part 202 ... Interference evaluation database 21 ... Control part 22 ... Personal Computer 23 ... Input unit 24 ... Display unit

Claims (3)

By introducing the atomized sample liquid into the high-frequency plasma, the components in the sample are excited to emit light having a wavelength that is unique to each element, and based on the emission spectrum obtained by spectroscopic measurement of the light. In the ICP emission spectroscopic analysis method for quantitative analysis of the elements,
For each of a plurality of various elements, a combination of a neutral atomic beam and an ion beam for each element and reference intensity information of those bright lines are stored in a storage means,
based rather by qualitative analysis in emission spectrum obtained by measuring a) target sample, if any of the elements that are stored in the storage unit is determined to be included in the said purpose the sample, the A first step of calculating the intensity ratio by obtaining the intensity of each of the neutral atomic beam and ion beam derived from the specific element from the emission spectrum ;
b) Measuring a standard sample to obtain an emission spectrum , and when the specific element is contained in the standard sample, each of a neutral atomic beam and an ion beam corresponding to the combination derived from the specific element While calculating the intensity ratio from the emission spectrum and calculating the intensity ratio, if the standard element does not contain the specific element, neutrality corresponding to the combination derived from another element different from the specific element After obtaining the intensity of each of the atomic beam and the ion beam from the emission spectrum, using the intensity and the reference intensity information stored in the storage means, the neutral atomic beam derived from the specific element and the ion beam A second step of estimating the intensity ratio;
c) Based on the difference between the intensity ratio calculated in the first step and the intensity ratio calculated or estimated in the second step, for evaluating the influence of physical interference and ionization interference during measurement of the target sample. A third step of generating information;
An ICP emission spectroscopic analysis method comprising: By introducing the atomized sample liquid into the high-frequency plasma, the components in the sample are excited to emit light having a wavelength that is unique to each element, and based on the emission spectrum obtained by spectroscopic measurement of the light. In an ICP emission spectroscopic analyzer for quantitative analysis of the above elements,
a storage means for holding a reference intensity information combinations and their emission lines of neutral atomic beams and ion beams to about it based Motogoto to a) a plurality of various elements,
b) Obtaining an emission spectrum for the target sample, and when it is determined by qualitative analysis based on the emission spectrum that any element stored in the storage means is included in the target sample, the specific element First intensity ratio calculation means for calculating the intensity ratio by obtaining the intensity of each of the neutral atomic beam and the ion beam corresponding to the combination derived from the emission spectrum ;
c) to obtain the emission spectrum for the standard sample, the when the standard specimen contains a pre Kitoku constant elements, each of the neutral atomic beam and ion beam corresponding to the combination from that particular element intensity one to calculate the strength of ratios determined from the emission spectrum, in the case does not contain the specific elements in the standard sample, corresponding to the combination from another element which is different from its specific element Neutral intensity beams and ion beams derived from the specific element using the intensity and reference intensity information stored in the storage means after obtaining the intensity of each of the atomic atomic beam and the ion beam from the emission spectrum Second intensity ratio calculating means for estimating the intensity ratio of
d) Physical interference during measurement of the target sample based on the difference between the intensity ratio calculated by the first intensity ratio calculating means and the intensity ratio calculated or estimated by the second intensity ratio calculating means. And evaluation information generating means for generating information for evaluating the influence of ionization interference,
An ICP emission spectroscopic analysis device comprising: The second intensity ratio calculation means is stored in the storage means, and is derived from the reference intensity information of the neutral atomic beam and the ion beam corresponding to the combination derived from the other element, and the specific element Each of the neutral atomic beam and the ion beam corresponding to the combination derived from the other element, obtained from the emission spectrum, using the reference intensity information of the neutral atomic beam and the ion beam corresponding to the combination. The ICP emission spectroscopic analyzer according to claim 2, wherein the intensity is standardized and the intensity ratio is estimated based on the standardized intensity .

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