JPH11118761A - Method and device for analyzing ions due to capillary cataphoresis - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simultaneously analyze an anion and a metal ion using cataphoresis by using an anion substance with a high complex stability constant to metal ions for a cataphoresis buffer liquid as the complex between the metal ions and anion property. SOLUTION: A sample 6 is loaded into a sample container 8 and is sealed, and the inside of the container 8 is pressurized and a buffer 12 at a cathode side is injected. Since the complex formation reaction of PDC (2,6-pyridine carboxylic acid) in the buffer 12 is fast, a complex can be formed immediately when the sample 6 is injected into a capillary 10 and is mixed with the PDC. A UV diode array detector 20 consists of a lens 24 for setting the light of a light source 22 into parallel beams, an optical slit 28 for alignment interface for aligning measurement rays by a shutter 26 and a cell 11 for detection of the capillary 10, a diffraction grating 30 for diffracting measurement rays according to the wavelength, and a diode array 32 for detecting the diffracted light at each wavelength, thus performing analysis with a single device and a single analysis condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for analyzing ions using capillary electrophoresis, and more particularly, to anions such as organic acids, fatty acids, aromatic carboxylic acids and inorganic anions. The present invention relates to a method and an apparatus for analyzing ions by capillary electrophoresis, which can simultaneously measure metal ions such as nickel, cobalt, copper, and zinc.

[0002]

2. Description of the Related Art Conventionally, anionic substances such as organic acids and inorganic anions have been measured using a separation analyzer such as ion chromatography or capillary electrophoresis, while metal ions such as nickel, cobalt and copper have been measured. Cationic substances including are analyzed by elemental analyzers such as an atomic absorption spectrometer, an inductively coupled plasma atomic emission analyzer (ICP / AES), an inductively coupled plasma mass spectrometer (ICP / MS), or ion chromatography or capillary electricity. It was measured using a separation analyzer such as electrophoresis.

[0003]

However, since anions and metal ions having different ionic properties cannot be measured at the same time, at least two measuring devices and conditions are required.
There is a problem that the number of devices is increased, and it is necessary to perform measurement under different measurement conditions, and it takes a long time to perform the measurement.

An object of the present invention is to solve the above-mentioned conventional problems, and it is an object of the present invention to be able to simultaneously analyze anions and metal ions using capillary electrophoresis.

[0005]

SUMMARY OF THE INVENTION The present invention uses an anionic substance having a high complex stability constant for metal ions as an electrophoresis buffer when analyzing ions using capillary electrophoresis. This problem has been solved by forming an anionic complex with metal ions.

Further, the anionic substance is 2,6-pyridinecarboxylic acid, ethylenediaminetetraacetic acid, or nitrilotriacetic acid.

Further, in an apparatus for analyzing ions using capillary electrophoresis, an electrophoresis buffer using an anionic substance having a high complex stability constant for metal ions, This object is also achieved by providing a capillary for separating the injected ions and a detector for simultaneously analyzing the separated anions and metal ions on the exit side of the capillary.

Further, the detector is a diode array detector capable of performing measurement by both the indirect absorbance method and the direct detection method, so that a single detector can perform high-precision measurement. is there.

2,6-pyridinecarboxylic acid (PDC),
Has a high complex stability constant for metal ions such as ethylenediaminetetraacetic acid and nitrilotriacetic acid (most often used as an indicator of the stability of a complex in solution, expressed as the reciprocal of the dissociation constant of the complex). By using an anionic substance having a high ability to form a complex with metal ions for the electrophoresis buffer (buffer), nickel, cobalt, copper ions and the like in the sample form a complex with, for example, PDC and are shown in FIG. It shows an anionic property. Therefore, it is possible to measure simultaneously with inorganic anions such as chloride ions and sulfate ions, and organic acids such as malic acid, citric acid and acetic acid.

FIG. 2 shows the complex stability constants for each metal of PDC that can be used as a buffer.

For example, PDC and a PDC metal complex such as nickel have ultraviolet (UV) absorption, and have a wavelength of 275 nm and a wavelength of 275 nm.
At 25 nm, the UV absorption is larger than the PDC of the buffer, so that a peak appears above the baseline as shown in FIG. In contrast, anions are PDC
The peak appears below the baseline because of the lower UV absorption. However, by selecting the measurement wavelength, it is also possible to invert the upside down and make the anions appear on the upper side as shown in FIG. 3 (B).

FIG. 3A shows a measurement wavelength of 275.10 n.
FIG. 3 (B) in the case of the direct detection method of m and the reference wavelength off.
Is measured wavelength 350.20 nm, reference wavelength 275.10
It is the case by the indirect absorbance method of nm.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 4 shows an overall configuration of an ion analyzer by capillary electrophoresis according to the present invention.

In this embodiment, a buffer 10 (cathode side) for separating a sample, which is introduced into the capillary 10 together with a capillary 10 for separating a sample and a sample 6 in a sample container 8, and separates the sample, 13 (anode side) and platinum electrodes 16 (cathode side), 17 at both ends of the capillary 10
A high-voltage power supply 14 for applying a high voltage of, for example, 5 to 30 kV to the (anode side), a detection cell 11 formed by peeling an outer wall (for example, polyimide) of the capillary 10, and both an indirect absorbance method and a direct detection method UV that can be measured by
And a diode array detector 20.

As shown in FIG. 5, the sample 6 placed in the sample container 8 is closed by closing the sample container 8 with a lid 9 and pressurizing the inside of the sample container, thereby forming a buffer 12 on the cathode side.
Is injected into. Since the complex formation reaction of PDC in the buffer is fast, the sample 6 is injected into the capillary 10 and the PDC
Upon formation, a complex is formed immediately.

The UV diode array detector 20 comprises:
As shown in detail in FIG. 6, a light source 22 composed of, for example, a deuterium lamp, a lens 24 for converting the light generated from the light source 22 into parallel rays, and a shutter 26 for turning on / off the measurement rays An alignment interface optical slit 28 for aligning the measurement light beam at the detection cell 11 of the capillary 10, and a diffraction grating 30 for diffracting the measurement light beam passing through the optical slit 28 according to the wavelength. For detecting the light diffracted by the diffraction grating 30 for each wavelength, for example, when the measurement wavelength is 1
It is configured using a diode array 32 of 90 to 600 nm.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The capillary 10 has an inner diameter of 50 μm,
A fused silica capillary having an outer diameter of 350 μm, a total length of 80.5 cm, and an effective length of 72 cm up to the detection cell 11 was used.
0.5 mM cetyltrimethylammonium bromide p
H5.77 was used. The applied voltage was measured at 25 kV, and the temperature of the capillary 10 was measured at 20 ° C. The sample was injected at 50 mbar for 8 seconds using the pressure method as shown in FIG. A UV diode array detector 20 is used for detection, and a substance having UV absorption such as nickel ions is detected using a direct detection method with a measurement wavelength of 275.10 nm and a reference wavelength off, and sulfate ions and organic acids are detected. For detection of a substance having almost no UV absorption, a measurement wavelength of 350.
An indirect absorbance method of 20 nm and a reference wavelength of 275.10 nm was used. FIG. 3 shows an example of measurement of an organic acid standard solution in this example.

FIG. 7 shows an example of simultaneous analysis of anions and nickel ions in the electroless nickel plating solution diluted 500 times.

The method of this embodiment and the conventional ICP / MS
FIG. 8 shows a comparison result of quantitative values of nickel in the electroless nickel plating solution measured in the step (1). As is clear from the figure, the results of both analyzes are in good agreement.

FIG. 9 shows an example of simultaneous analysis of anions and copper ions in a 500-fold diluted electroless copper plating solution.

In this embodiment, the detector is UV
Since a diode array detector is used, measurement by both the indirect absorbance method and the direct detection method is possible with one detector, and the configuration is simple.

The type of the detector is not limited to this. The measurement wavelength is not limited to the embodiment or the example. The type of the capillary is not limited to the fused silica capillary. The buffer is not limited to PDC, and other anionic substances having a high complex stability constant for metal ions, such as ethylenediaminetetraacetic acid and nitrilotriacetic acid, can be used.

[0024]

According to the present invention, analysis of anions and metal ions, which conventionally required two or more analyzers and conditions, can be performed simultaneously with one analyzer and one analysis condition. Thus, simultaneous analysis of anions and metal ions becomes possible in a short time (7 minutes in the example).

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a complex formed by a buffer, for illustrating the principle of the present invention.

FIG. 2 is a table showing a complex stability constant of PDC as an example of a buffer with respect to each metal;

FIG. 3 is a diagram showing a measurement example of an organic acid standard solution for explaining the principle of the present invention.

FIG. 4 is a cross-sectional view showing the overall configuration of an ion analyzer by capillary electrophoresis according to an embodiment of the present invention.

FIG. 5 is a sectional view showing a method of injecting a sample into a capillary in the embodiment.

FIG. 6 is a perspective view showing a configuration of a UV diode array detector used in the embodiment.

FIG. 7 is a diagram showing an analysis example of an electroless nickel plating solution according to the present invention.

FIG. 8 shows the method of the present invention and an IC to show the usefulness of the present invention.
Chart showing comparison of quantitative values of nickel in electroless nickel plating solution measured by P-MS

FIG. 9 is a diagram showing a measurement example in an electroless copper plating solution according to the present invention.

[Explanation of symbols]

 6 ... Sample 8 ... Sample container 10 ... Capillary 12, 13 ... Buffer 14 ... High voltage power supply 16, 17 ... Platinum electrode 20 ... UV diode array detector 22 ... Light source 30 ... Diffraction grating 32 ... Diode array

Claims (4)

[Claims] In the analysis of ions using capillary electrophoresis, an anionic substance having a high complex stability constant with respect to metal ions is used as an electrophoresis buffer, and metal ions and anionic substances are analyzed. An ion analysis method by capillary electrophoresis, wherein anions and metal ions are simultaneously analyzed by forming a complex of the following. 2. The method according to claim 1, wherein the anionic substance is 2,6-pyridinecarboxylic acid, ethylenediaminetetraacetic acid, or nitrilotriacetic acid. 3. An apparatus for analyzing ions using capillary electrophoresis, comprising: an electrophoresis buffer in which an anionic substance having a high complex stability constant for metal ions is used; Ion analysis by capillary electrophoresis, comprising: a capillary for separating the injected ions; and a detector for simultaneously analyzing the separated anions and metal ions on the exit side of the capillary. apparatus. 4. An ion analyzer according to claim 3, wherein said detector is a diode array detector capable of performing measurement by both an indirect absorbance method and a direct detection method.