JPH02183146A - Measurement of iron ion concentration - Google Patents

Abstract

PURPOSE:To enable measurement of concns. of bivalent and trivalent iron ions by injecting a liquid to be measured and an oxidizing agent into a passage of a color identification reagent solution to measure an absorbance. CONSTITUTION:A color identification reagent solution 1 is sent to an injector 5 to be measured with a constant amount pump 2 through an oxidizing agent injector 3 and a valve of the injector 5 is changed over to a valve 52 to inject a liquid 6 to be measured stored in a fixed amount into a spiral tube 53 into the solution 1 with a constant amount pump 8 so that it is fed into an absorptiometric cell 11 via a fluororesin tube 9 and a thermostatic cell 10 to determine Fe<3+> form a color in the cell 11. Then, the solution 1 is sent to an oxidizing agent injector 3 with the pump 2 and a valve of the injector 3 is changed over to a valve 32 to inject an oxidizing agent 4 stored in a fixed amount in a tube 33 into the solution 1 with a constant amount pump 7 and then the solution is sent to the injector 5, with which 5 a fixed amount of the liquid 6 to be measured to make Fe form a color in total with the oxidation of Fe<2+> in the liquid 6 to be measured to the Fe<3+>. Then, the total Fe is determined in the cell 11. Thus, a density of Fe<2+> can be obtained in the liquid 6 to be measured by subtracting the concn. of the Fe<3+> from the concn. of the total Fe thus obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for measuring the concentration of iron ions contained in alloy plating such as Ni-Fe.

[Conventional technology]

Currently, alloy plating films are used as excellent magnetic materials, especially N
Permalloy plating film, which is an alloy of i-Fe, is often used. In this permalloy plating film, compositional fluctuations on the order of 0.1% significantly affect the quality of its function as a magnetic film.

Therefore, in order to obtain a permalloy magnetic film with good functionality, it is necessary to control the concentration of iron ions such as Fe""Pe3+ in the plating bath with high precision and quickly.

By the way, conventional methods for analyzing divalent and trivalent iron ions include ion exchange chromatography and flow injection. In the ion-exchange chromatography method, a mixed solution of the sample is placed at the top of a column made of ion-exchange resin or other ion-exchange material, developed with an appropriate electrolyte solution, and the component ions are separated based on the differences in their exchange adsorption properties to the resin. The flow injection silane method uses a metering pump to create a controlled continuous flow, and performs various reactions such as color reactions or separations in this flow, and This method analyzes the components of a solution using a detector installed at the

However, since the above-mentioned ion chromatography method requires a long time for measurement and has problems with analysis accuracy, recently there has been a tendency for flow injection method to be used more frequently.

In general, there are two types of flow injection method detectors: those that detect absorbance or atomic absorption, and those that detect electrically.In order to perform high-precision analysis in the high concentration range of plating baths, absorbance detection is required. It is considered that the device is effective. A method for quickly measuring the concentrations of Fe'' and Fe'' in an alloy in the same system by flow injection using an absorbance detector is described in "Analytical Chemistry, No. 369.
-, PP515° (19B?)'', the example described below has been reported. First of all, 4,7-diphenyl-1
, 10-phenanthrolinesulfonic acid is used as a coloring reagent to measure the Fe2+ concentration, and on the other hand, ascorbic acid is used as a reducing agent to reduce Fe3° to Fe3+, and the total Fe concentration is measured. Then, the Fe'' concentration is obtained by determining the difference between the total Fe concentration and the previously measured Fe'' concentration.

Further, as a method for quantifying the Fe'' concentration in an alloy plating bath by a flow injection method using an absorbance detector, an example using ammonium thiocyanate or sulfosalicylic acid as a coloring reagent has been reported.

[Problem to be solved by the invention]

However, the above-mentioned 4,7-diphenyl-1,10
- In the method of quantifying the respective concentrations of Fe"° and Fe" in the alloy by combining phenanthroline sulfonic acid and ascorbic acid, the concentration of Fe3+ in the alloy is from 0.5 to
1.5mg/42, and is intended for analysis in the low concentration range. Therefore, in order to analyze the high concentration range in a plating bath where the concentration of Fe3" is 100mg/1 or more, it is necessary to dilute the liquid to be measured. This results in problems such as complicated analysis operations, long analysis times, and deterioration of analysis accuracy.
In order to analyze e3+, a method using sulfosalicylic acid as a coloring reagent is considered effective. However, since sulfosalicylic acid itself does not react with Fe'', it is necessary to oxidize Fe'' to Fe34 in order to quantify Fe'' using sulfosalicylic acid.
Since e'' is relatively unstable, it is necessary to measure the concentration of Fe'', Fe'' in as short a time as possible and with high precision.

The present invention has been made in view of the above circumstances, and includes an oxidizing agent injector of "Fe" in addition to the liquid to be measured injector in the middle of the route for sending a solution containing a coloring reagent to an absorptiometer. Into the flow path of the solution containing the color reagent, a fixed amount of the sample liquid for alloy plating containing Fe"° and Fe" and the oxidizing agent are injected using a sample injector and an oxidizing agent injector, and the absorbance of the PE3+ and the F
The absorbance of total Fe in the liquid to be measured, which has been colored due to oxidation of e1, is measured to determine the concentration, and the total Fe? a degree and p e 3
+Concentration ゛Calculate the difference between p e! It is an object of the present invention to provide a method for quickly and highly accurately measuring the respective divalent and trivalent iron ion concentrations in a liquid to be measured by determining the + concentration.

[Means to solve the problem]

The iron ion concentration measurement method in an alloy plating bath according to the present invention uses a liquid to be measured injector installed in the middle of a path for sending a solution containing a coloring reagent to an absorbance cell, and injects F into the flow path of the solution.
In the method of measuring the iron ion concentration of the liquid to be measured by injecting a certain amount of the liquid to be measured containing e'' and Fe'', causing the iron ions to develop color, and detecting the absorbance, the
3. A process of developing color and measuring its concentration, and installing an oxidizing agent injector for Fe'' in the middle of the path, injecting the oxidizing agent into the flow path of the solution with the oxidizing agent injector, F
A process of oxidizing to e3+, a process of coloring the total Fe in the liquid to be measured and measuring its concentration, and calculating the difference between the total Fe concentration and the Fe32+ concentration to determine the Fe'' concentration. It is characterized by having a process.

[Effect]

In the iron ion concentration measuring method of the present invention, in addition to the sample injector placed in the middle of the path for sending the solution containing the coloring reagent to the spectrophotometric cell, an oxidizing agent injector of "Fe" is provided, A liquid to be measured containing Fe'' and p e 2 * and an oxidizing agent are injected into the flow path of a solution containing a coloring reagent using a measuring injector and an oxidizing agent injector, and the absorbance of colored Fe'+ and pe2+ are measured.
The concentration is determined by measuring the absorbance of all Fe in the liquid to be measured, which is oxidized to Fe'° and colored. Then, calculate the difference between the total Fe concentration and the Fe''''' concentration to calculate the Fe concentration in the liquid to be measured.
Since the 2+ concentration is determined, the divalent and trivalent iron ion concentrations in the liquid to be measured can be measured quickly and with high clarity.

〔Example〕

The method of the present invention will be specifically explained below based on drawings showing examples thereof. FIG. 1 is a schematic diagram showing the configuration of an apparatus for carrying out the method of the present invention, and 1 in the figure indicates a coloring reagent such as sulfosalicylic acid.

First, for the coloring reagent solution 1, use the metering pump 2 and the oxidizing agent injector 3.
sent to. The oxidizing agent injector 3 is equipped with a valve 31 for flowing the coloring reagent solution l and a valve 32 for flowing the oxidizing agent 4. When injecting the oxidizing agent 4 into the flow path of the coloring reagent 2+, the oxidizing agent 4 is It is possible to automatically switch to the valve 32 that allows the flow of water. Further, a spiral tube 33 for storing a certain amount of oxidant is provided inside or outside of the oxidizing agent injector 3, and by switching the oxidizing agent 3 to a valve 32 for flowing the oxidizing agent 4, The oxidizing agent 4 is stored in a fixed amount in a spiral tube 33, and is further injected into the flow path of the coloring reagent solution 2+ by a metering pump 7.

When measuring "Fe" in the reagent solution 6, the coloring reagent solution 1 sent to the oxidizing agent injector 3 is passed through the valve 31 through which the coloring reagent 1 is passed without injecting the oxidizing agent 4. ,
It is sent to the injector 5 to be measured. On the other hand, the total F in the liquid to be measured 6
When measuring e, switch the valve of the oxidizing agent injector 3 to the valve 32 through which the oxidizing agent 4 flows, and inject a certain amount of the oxidizing agent 4 accumulated in the tube 33 into the flow path of the coloring reagent solution 2+ using the metering pump 7. and is sent to the injector 5 to be measured.

The measuring injector 5 is equipped with a valve 51 for flowing the coloring reagent solution 1 and a valve 52 for flowing the measuring liquid 6. When injecting the measuring liquid 6 into the flow path of the coloring reagent solution 2+, It is possible to automatically switch to the valve 52 that allows the liquid to be measured 6 to flow. Further, a spiral tube 53 for storing a certain amount of the liquid to be measured 6 is provided inside or outside of the syringe to be measured 5, and the syringe to be measured 5 is connected to a valve 52 through which the liquid to be measured 6 flows. By switching, a certain amount of the liquid to be measured 6 is stored in the spiral tube 53, and is further injected into the flow path of the coloring reagent solution 1 by the metering pump 8. In other words, in both the coloring reagent solution 1 for measuring the concentration of Fe3'' sent to the syringe to be measured 5 and the coloring reagent solution I containing the oxidizing agent 4 for measuring the concentration of total Fe, By switching the valve of the injector 5 to be measured to the valve 52 through which the liquid to be measured 6 flows, a fixed amount of the liquid to be measured 6 accumulated in the tube 53 is injected by the metering pump 8.The liquid to be measured 6
The injected coloring reagent solution 1 and the coloring reagent solution 1 containing the oxidizing agent 4 exit the syringe 5 to be measured and pass through a tube 9 into a constant temperature bath 10 controlled within ±0.5°C. After that, it flows into the absorbance measurement cell 11, and an absorbance detector (not shown) detects the absorbance of all Fe in the colored solution by oxidizing Fe" and Fe" in the colored solution to Fe3+, and determines the concentration. be measured. Therefore, the total F in the solution
The Fe'' concentration in the solution is determined by subtracting the Fe'' concentration from the e concentration. As mentioned above, the concentration of Fe'' and Fe2 is measured by intermittently injecting the oxidizing agent 4 and the liquid to be measured 6 into the coloring reagent solution l using the oxidizing agent syringe 3 and the measuring syringe 5, respectively. By injecting F into the liquid to be measured 6,
e” and Fe” concentrations are automatically measured alternately. The oxidizing agent 4 used in the method of the present invention may be one that can quickly and completely oxidize Fe'' and does not react with coloring reagents such as sulfosalicylic acid, such as hydrogen peroxide that does not generate bubbles in the tube. In addition, the injection amounts of the oxidizing agent 4 and the liquid to be measured 6 may preferably be 10 uff or more each in order to speed up the oxidation reaction and improve the precision of analysis.

Furthermore, the oxidizing agent 4 and the liquid to be measured 6 are added to the coloring reagent solution 1, respectively.
The metering pump 7.8 used when injecting the iron ions was used to further improve the reproducibility of the iron ion concentration obtained by strictly regulating the flow rate. The desired iron ion concentration is obtained.

Next, an example will be described in which the concentration of peZ+ and pe++ in a Ni'-Fe alloy plating bath is measured using the method described above. Using a 1% concentration sulfosalicylic acid solution as the coloring reagent solution 1 and a 5% concentration hydrogen peroxide solution as the oxidizing agent 4, Fe3° in the Ni-Fe alloy plating bath was first used.
Measure concentration. Metering pump 2 for sulfosalicylic acid solution
By 2mj! The oxidizer is sent through the oxidizer syringe 3 to the syringe to be measured 5 at a flow rate of /min. In the syringe to be measured 5, the valve is made of Ni-F.
The valve 52 is switched to flow the liquid to be measured 6, which is the e-alloy plating solution, and 20 μl of the liquid to be measured 6 is injected into the sulfosalicylic acid solution using a metering pump. Then, the sulfosalicylic acid solution containing the liquid to be measured 6 was passed through a fluororesin tube 9 with an inner diameter of 0.5 mm and a length of 3 m, and heated to a temperature of 22 ± 0.5°C.
The optical path length after passing through a constant temperature bath 10 maintained at
The sample is poured into the Il absorbance cell 11. An absorbance detector (not shown) is used to quantify the colored Fe"° in the absorbance cell 11 at a wavelength of 500 nm. Next, the total Fe concentration in the Ni--Fe alloy plating bath is measured.

A sulfosalicylic acid solution, which is a coloring reagent solution, was pumped to 2 m by metering pump 2! to oxidant injector 3 at a flow rate of /min.

In the oxidizing agent injector 3, the valve is injected with the oxidizing agent 4, which is a hydrogen peroxide solution.
50 μ2 of oxidizing agent 4 is injected and sent to the syringe 5 to be measured. In the measuring injector 5, in the same manner as described above, 20 μ2 of the liquid to be measured 6 is injected, and Fe'' in the liquid to be measured 6 is oxidized to Fe3+, so that all Fe is colored.The oxidizing agent 4 and the liquid to be measured are The sulfosalicylic acid solution into which the liquid 6 was injected is passed through the tube 9 under the same conditions as above, and after passing through the constant temperature bath lO kept at 22±0.5°C, it is passed through the absorbance cell 11 with the optical path length 1101a. Then, the total Fe in the absorbance cell 11 is quantified at a wavelength of 500 nm using an absorbance detector (not shown).

Therefore, by subtracting the previously obtained Fe'' concentration from the total Fe concentration, the Fe'' concentration in the Ni--Fe alloy plating solution can be obtained.

Figure 2 shows how Fe' in a solution is removed by the method of the present invention.

This is a graph showing the relationship between the peak area value of the detected peak and the measurement time when oxidized to
a, u,), and time (seconds) is shown on the horizontal axis.

In FIG. 2, it can be seen that each peak was obtained when measurements were performed three times, and that all measurements were completed within 5 minutes.

In other words, even when measuring the concentrations of both "Fe" and "Fe" in a solution using the method of the present invention, it is possible to perform the measurement within 10 minutes, allowing extremely rapid analysis.

. Figure 3 shows the peak area value of the detected peak and Fez+ when Pe'' in the solution is oxidized to Fel+ by the method of the present invention.
This is a graph showing the relationship with concentration, where the vertical axis shows the peak area value (a, u,) and the horizontal axis shows the concentration (g/I!, ).
are each other. As is clear from FIG. 3, the straight line obtained exhibits excellent linearity, indicating the excellent reproducibility of the method of the invention. In addition, the quantitative accuracy of Fe3° in the method of the present invention is within ±0.1%, and Fe""
Since the quantitative accuracy of Pa3+ when oxidizing Fe is also within ±0.1%, the quantitative accuracy of Fe''- is maintained within ±0.2%, and from this, the method of the present invention is highly accurate. It can be seen that the reproducibility is excellent.

〔effect〕

As detailed above, in the method for measuring iron ion concentration according to the present invention, in addition to the syringe to be measured, which is installed in the middle of the route for sending a solution containing a coloring reagent to an absorbance cell, A reagent injector is installed, and Fe" is placed in the flow path of the solution containing the coloring reagent.
+ A liquid to be measured containing Fe'+ and an oxidizing agent were injected using the respective syringes mentioned above, and the absorbance of colored Fe3+ and Fe
The concentration is determined by measuring the absorbance of all Fe in the liquid to be measured, which is colored by oxidation of 1 to Fe3''. Since the Fe concentration is calculated by calculating the difference between the total Fe concentration and the PeIs concentration, the concentration of each Fe in the plating bath can be measured quickly, with high precision, and with good reproducibility.
The present invention has excellent effects, such as contributing to the stabilization of plating operations and the development of high-quality plating films.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration of an apparatus for carrying out the method of the present invention, and FIG. 2 is a schematic diagram showing the structure of an apparatus for carrying out the method of the present invention.
FIG. 3 is a graph showing the relationship between the peak area value of the detected peak when oxidized to 3+ and the measurement time, and FIG. It is a graph showing the relationship with the concentration of "Fe". l... Coloring reagent solution 2... Metering pump 3...
Oxidizing agent injector 4... Oxidizing agent 5... Injector to be measured 6... Liquid to be measured 7, 8... Metering pump 9...
Tube 11... Absorbance cell patent Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent attorney Noboru Kono +20 Time (seconds) Figure 1.0 2.0 Fe concentration (q/α) Figure

Claims (1)

[Scope of Claims] 1. A liquid to be measured injector installed in the middle of a path for sending a solution containing a coloring reagent to an absorbance cell, which injects Fe^2^+ and Fe^3 into the flow path of the solution. In a method of measuring the iron ion concentration of a liquid to be measured by injecting a certain amount of a liquid to be measured containing Fe^3+, coloring the iron ions, and detecting the absorbance, The process of measuring the concentration, and installing an Fe^2^+ oxidizer injector in the middle of the path,
Injecting an oxidizing agent into the flow path of the solution with the oxidizing agent injector,
A process of oxidizing Fe^2^+ to Fe^3^+, a process of coloring the total Fe in the liquid to be measured and measuring its concentration, the concentration of the total Fe and the concentration of the Fe^3^+. A method for measuring iron ion concentration, comprising the step of determining the concentration of Fe^2^+ by calculating the difference between the two.