JPH01224661A - Analysis of iron - Google Patents

Abstract

PURPOSE:To improve determination accuracy by introducing a liquid sample contg. iron bivalent and tervalent ions into a flow passage of a liquid chromatograph and supplying an eluate contg. a prescribed concn. of iron bivalent ions thereto, then separating the iron bivalent and tervalent ions in the sample in a sepn. column. CONSTITUTION:The acidic eluate contg. 0.2ppm iron bivalent ions is housed in an eluate chamber 1. This eluate is fed at a prescribed flow rate to the sepn. column 4 by a chemical resistant liquid feed pump 2. The liquid sample contg. the iron bivalent and tervalent ions is introduced by an injector 3 having a constant volume loop into the flow passage of the liquid chromatograph. A reagent liquid from a liquid chamber 8 is continuously supplied between the column and a reaction coil 5 by a ceramics pump 7. A color forming reaction is progressed in the coil 5 consisting of tetrafluoroethylene and the reaction liquid is introduced into a flow cell of a UV.visible light absorptiometer 6, by which the iron bivalent and tervalent ions are measured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for analyzing iron, and particularly to an analysis method suitable for analyzing iron ions by liquid chromatography.

[Conventional technology]

The conventional method for analyzing divalent iron ions and trivalent iron ions is specified in JIS-0102, Factory wastewater test method [
Phenanthroline spectrophotometry
Divalent iron is measured as is, and trivalent iron is reduced to divalent iron.

In addition, in the flow injection method (FIA method), a double flow cell of a spectrometer is used, and in the first cell, divalent iron and orthophenanthroline undergo a color reaction.
In the second cell, trivalent iron is reduced to divalent iron using a reducing agent, and the color reaction with orthofendroline is detected to determine total iron, and from the difference between the measured values of total iron and divalent iron. I am looking for the concentration of trivalent iron ions.

[Problem to be solved by the invention]

None of the above-mentioned conventional methods can measure both divalent iron ions and trivalent iron ions using only one flow path.

Therefore, the inventors tried a method of measuring iron using liquid chromatography. However, when a sample containing divalent iron ions and trivalent iron ions is introduced into a liquid chromatograph and separated and analyzed using the usual method, tailing and leading occur in the Fez+ and Fe'' peaks, making it difficult to achieve high quantitative accuracy. I found out what I can't get.

The purpose of the present invention is to obtain iron 2 by liquid chromatography.
An object of the present invention is to provide an iron analysis method that can improve the peak profile when separating valent ions and trivalent iron ions and improve quantitative accuracy.

[Means to solve the problem]

The present invention introduces a liquid sample containing divalent iron ions and trivalent iron ions into a flow path of a liquid chromatograph, and supplies an eluent containing divalent iron ions at a predetermined concentration to remove the iron ions in the sample. It is characterized in that valent ions and trivalent iron ions are separated by a separation column, and the liquid eluted from the separation column is guided to a detector.

[Effect]

The tailing phenomenon of divalent iron ions and the leading phenomenon of trivalent iron ions that occur when a sample containing iron ions is separated and analyzed by liquid chromatography can be avoided by adding 0.1 to 2 ppm of divalent iron ions in the eluent in advance. The inventors have found that it can be significantly reduced by adding a predetermined concentration within the range of .

This is because the rate at which divalent iron ions in the sample are oxidized by dissolved oxygen while moving through the column is suppressed by the divalent iron ions already present in the eluent;
It is thought that this is because the reaction in which valent ions are reduced to divalent iron ions in the column is significantly suppressed by divalent iron ions in the eluent, but the details are not clear.

If divalent iron ions coexist in the eluent, the baseline of the chromatogram will rise somewhat, but peak tailing and leading can be reduced and the symmetry of the peak shape can be improved. If the concentration of divalent iron ions present in the eluent is less than 0.1 ppm, little effect will be observed, and if it is more than 2 ppm, noise will increase, making high-sensitivity analysis difficult. .

〔Example〕

The present invention is suitable for analyzing samples such as magnetic materials and plating liquid. In a preferred embodiment, a separation column of a liquid chromatograph is packed with a cation exchange resin, and a reagent solution containing a coloring agent and a reducing agent is continuously added to the eluate from the separation column while flowing through a reaction coil. Allow the coloring reaction to proceed. In this case, an absorption photometer is used as a detector.

Iron can also be analyzed without producing a color reaction. That is, the outlet of the separation column is connected to the sample inlet of an atomic absorption spectrometer, or the inductively coupled plasma spectrometry (I
By connecting to the sample inlet of CP), Fe'' and Fe3+ separated by the column can be quantified.

In this case, an atomic absorption spectrophotometer or ICP acts as a detector.

In the case of solid samples, a series of reaction vessels are arranged on a turntable that moves intermittently, which can be processed by systemizing a pretreatment device and a liquid chromatography device. The solid sample is reacted with acid, and the solid sample is dissolved while being transferred through a row of containers. The dissolved sample is diluted to a predetermined ratio and introduced into the flow channel through the nozzle of the sampler of the liquid chromatograph. In this case as well, the eluent supplied to the separation column has a predetermined concentration of iron2.
Contains valence ions.

As the reagent solution added to the eluate from the separation column, a 0.4N aqueous potassium hydroxide solution containing orthophenanthroline, which is a coloring agent, and ascorbic acid, which is a reducing agent, is used.

FIG. 1 shows a flow path diagram of a liquid chromatograph to which the present invention is applied.

The eluent tank 1 contains an acidic eluent containing 0.2 ppI11 of divalent iron ions. This eluent is sent to the separation column 4 at a predetermined flow rate by the chemical-resistant liquid sending pump 2. This pump 2 uses ceramics and gold (Au) for its liquid contact parts to provide acid resistance. A liquid sample containing iron ions is introduced into the channel of the liquid chromatograph by an injector 3 having a constant volume loop 3'. As the injector 3, a commercially available ceramic injector was used.

The separation column 4 is a glass cylinder filled with a strongly acidic cation exchange resin made of a copolymer of styrene and divinylbenzene. In the flow path between the separation column 4 and the reaction coil 5, the reagent liquid from the liquid tank 8 is passed through the ceramic pump 7.
Continuously supplied by A coloring reaction proceeds within the reaction coil 5 made of tetrafluoroethylene, and the reaction solution is led to a flow cell of an ultraviolet/visible absorption photometer 6.

FIG. 2(B) shows a chromatogram obtained in the example of FIG. 1. A liquid sample containing 50 ppm of Fez+ and 1100 ppm of Fe3+ was placed in a liquid chromatograph.
0 μQ was injected and the measurement was performed under the separation conditions shown in Table 1 (b). First, the divalent, first and then the trivalent components elute, and it took about 14 minutes to complete the measurement.

Table 1 FIG. 2 (A) is an example of a chromatogram measured for comparison, and was measured under the separation conditions shown in Table 1 (a). The other conditions were the same as those in FIG. 1(B). In FIG. 2(A), the peak of Fe"0 causes tailing, and the peak of FeB+ causes tailing. In contrast, in FIG.
In B) 5, the shape of the peak is almost symmetrical, the sensitivity is improved, and the analysis time is shortened to 1/2. In the case of Figure 2 (A), accurate quantitative values cannot be obtained due to the way the baseline is drawn, and the peak height is low, reducing the separation rate to 100.
It takes a long time to reach %.

〔Effect of the invention〕

According to the present invention, divalent iron ions and trivalent iron ions can be analyzed in the same flow path, the peak profile of the separated components can be improved, and the quantitative accuracy can be improved.

[Brief explanation of the drawing]

FIG. 1 is a flow path diagram of a liquid chromatograph used in an embodiment of the present invention, and FIG. 2 is a diagram showing an example of a chromatogram. 1... Eluent tank, 3... Injector, 4... Separation Karayu 1 day

Claims (1)

[Claims] 1. A liquid sample containing divalent iron ions and trivalent iron ions is introduced into a flow path of a liquid chromatograph, and an eluent containing divalent iron ions at a predetermined concentration is supplied to produce the sample. A method for analyzing iron, comprising separating divalent iron ions and trivalent iron ions therein using a separation column, and guiding a liquid eluted from the separation column to a detector. 2. The method for analyzing iron according to claim 1, wherein the detector is an atomic absorption spectrophotometer or an inductively coupled plasma analyzer. 3. In the analysis method according to claim 1, a reaction reagent solution containing a coloring agent is added to the flow path between the separation column and the detector, and an absorption photometer is used as the detector. Characteristic iron analysis method. 4. React the solid sample containing iron with acid in a container, dissolve the solid sample while moving the container, introduce the dissolved sample into the channel of the liquid chromatograph, and collect iron divalent ions. An iron analysis method characterized by separating the components of a sample using an eluent containing.