JPH0446379B2 - - Google Patents

Description

Detailed Description of the Invention (a) Field of Industrial Application The present invention relates to a method and apparatus for analyzing amine compounds and ammonia, and in particular to a method for selectively and sensitively detecting amine compounds and ammonia in a gas chromatographic analysis method. The present invention relates to an amine compound and ammonia detection method and device.

(B) Prior art The analysis of amine compounds and ammonia is essential in the measurement of pollutants or the analysis of biological samples. Conventionally, analysis of amine compounds and ammonia has been carried out using a thermal ionization detector, a fluorescence detector using a post-column method, or a colorimetric method. However, all of them had problems in terms of selectivity and sensitivity.

For example, a thermal ionization detector is an excellent detector for nitrogen compounds as a detector for a gas chromatograph analyzer, but it detects all nitrogen-containing compounds and is selective for amine compounds and ammonia. Therefore, it is difficult to detect only amine compounds using a thermal ionization detector. Additionally, this method uses ppb
It cannot be said to be practical because it lacks order sensitivity and has poor reproducibility. Furthermore, thermal ionization detectors require the use of hydrogen gas, which is always dangerous and requires extreme caution in analytical operations, which remains a problem.

Therefore, for example, the analysis of ammonia, trimethylamine, etc., which are regulated by the Offensive Odor Prevention Act, requires a special concentration operation and must rely on various analyses, which is inconvenient and requires unification of analytical methods. was exactly what was desired.

(c) Purpose The present invention solves all the problems of conventional methods in the analysis of amine compounds and ammonia, and has sensitivity on the order of ppb, excellent selectivity,
The present invention provides a method for analyzing amine compounds and ammonia that has good reproducibility and is suitable for unifying analytical methods, and an apparatus therefor.

(d) Structure The present invention is a method of mixing a mixed gas of an amine compound and ammonia analysis sample gas with an oxygen-containing gas using heated metallic iridium, an oxide of this metal, or a combination of iridium and an oxide. A method for analyzing amine compounds and ammonia, which is characterized by contacting a solid with a substance and measuring the ionization current of the decomposed gas, and the present invention also includes:
an electrode connected to a heating power source, at least a part of which is made of metallic iridium, an oxide, or a combination of iridium and oxide; a nozzle facing the electrode; An amine compound and ammonia analyzer characterized by comprising a sample gas and oxygen-containing gas flow path connected to a sample gas and an oxygen-containing gas flow path, and an ionization current measuring electrode.

In the present invention, the amine compound refers to primary amine compounds, secondary amine compounds, tertiary amine compounds, ammonia compounds, etc., and also refers to organic compounds and inorganic compounds.

In the present invention, in order to transport the sample gas,
A carrier gas and an oxygen-containing gas are used.
The oxygen-containing gas is a gas containing oxygen, and the gas component coexisting with oxygen must be an inert gas. Therefore, as an oxygen-containing gas,
Oxygen gas, air, etc. are commonly used. As seen in thermal ionization detectors, hydrogen gas impairs selectivity, so mixing with oxygen gas must be avoided. By avoiding the incorporation of hydrogen gas in this manner, generation of hydrogen plasma can be avoided and positive ions can be detected.

In the present invention, iridium and iridium oxide have a large work function of 500 or more.
It exists stably at temperatures as high as 1000°C. Amine and ammonia come into contact with the surface of these oxides and positive ions are formed.

Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings, but the technical scope of the present invention is as follows:
This explanation is not intended to be limiting in any way.

(E) Example FIG. 1 is a schematic explanatory diagram showing one embodiment of the method for analyzing amine compounds and ammonia and the analyzer thereof according to the present invention, and FIG. 2 is a schematic explanatory diagram showing another embodiment. It is an explanatory diagram.

3 and 4 are chromatograms showing the sensitivity, selectivity, and reproducibility of the detector shown in FIG. 1 to amine compounds and ammonia.

The detector for analyzing amine compounds and ammonia in the analyzer of this example is designated as a whole by reference numeral 1, and is used as a detector for a gas chromatograph analyzer.

The separation column is connected via a T-joint 3 to a quartz nozzle 4 of the detector, the other tube 5 connected to the T-joint adding oxygen to the gas stream leaving the separation column 2. or to an oxygen or air source (not shown) for mixing air. The open end 6 of the quartz nozzle 4 opens into the ionization chamber 7 , and the nozzle electrode 8 is connected to a high voltage power source 9 . In this example, the nozzle electrode 8 is connected to the negative side of the voltage power source. The high voltage power supply 9 is a DC power supply and generally has a voltage of 200 to 300 volts.

The ionization chamber is provided with an oxygen or air supply port 10 for further supplying oxygen or air around the quartz nozzle 4. This oxygen or air is
This is to maintain an oxygen atmosphere inside the ionization chamber, and it is preferable to provide a diffusion plate or the like at the oxygen or air supply port so that the oxygen gas is uniformly dispersed.

A collector electrode 11 is provided in the ionization chamber 7 opposite to the nozzle electrode 8 . The collector electrode 11 is formed by integrally forming a cylindrical inner collector electrode 12 and an outer collector electrode 13 via an electrically insulating cylinder 14 made of ceramic. The cylindrical outer collector electrode 13 extends beyond the end of the inner collector electrode 12 and surrounds the electrode 15.
The amine compound and ammonia come into contact with each other and are provided so as to capture the electron flow generated during ionization. As the electrode 15, an iridium wire whose surface is coated with iridium oxide is used.
However, before measurement, the iridium wire electrode 15, which has iridium oxide formed on its surface,
It may be manufactured by heating the already provided iridium wire electrode 15 in an oxygen-containing gas atmosphere to form an iridium oxide film on the iridium wire. Moreover, this electrode 15 can be connected to a heating power source and provided so that it can be heated to an arbitrary temperature. Electrode 15 is nozzle electrode 8
For example, it is fixed at a position about 6 mm away from the center. When the measurement signal is a negative signal, the nozzle electrode 8
is connected to the negative side of the high voltage power supply 9, in which case the electrode 15 is attached with one end connected to the end of the inner collector electrode 12 and the other end connected to the end of the outer collector electrode 13. It can be heated electrically.

The other end of the outer collector electrode 13 is a transformer 16
It is connected to the power controller 17 via. The other end of the inner collector electrode 12 connects one end of the secondary side of the transformer 16 to an electrometer 18 .

FIG. 2 shows an embodiment in which the measurement signal is a positive signal, and the nozzle electrode 8 is connected to the positive side of the high voltage power source 9. In this example, the electrode 15 is
It is connected to the heating power source 19, the nozzle electrode 8, and the positive side of the high voltage power source 9. Therefore, in this example, unlike the example in FIG.
Collector electrode 15 is immediately connected to electrometer 18
is connected to. In both the example of FIG. 1 and the example of FIG. 2, the electrometer 18 is connected to a recorder 20 and a data processor 21 (not shown in FIG. 1).

In the embodiment of the invention shown in FIGS. 1 and 2, the amine compound and ammonia detector 1
is formed in such a structure, the sample gas flowing out from the separation column 2 is mixed with the air introduced from the tube 5 at the T-joint 3.
This amount of air is between 20 and 80 ml/min.

The sample gas mixed with air flows into the ionization chamber 7 from the tip of the quartz nozzle 4. Ionization chamber 7
The sample gas flowing into the sample gas is further mixed with air at a rate of 20 to 100 ml/min, and is thermally decomposed upon contact with the heated electrode 15, and the amine compound and ammonia are ionized to generate positive ions. These positive ions are captured by the collector electrode 11, amplified by the electrometer 18, and then transferred to the recorder 20 and data processor 21.
The signal is transmitted and recorded.

The nozzle electrode 8 and the heated platinum electrode 15 are connected to the positive side of a high-voltage power source (200 to 300 volts), and a positive DC voltage is applied. Therefore, the collector electrode 11 is negative, and decomposition is generated. The positive ions are captured and measured as ion current. On the other hand, when the nozzle electrode 8 is connected to the negative side of a high-voltage power supply (200 to 300 volts), the collector electrode 11 becomes positive, and captures the electrons released when decomposed to generate positive ions. Measured as electric current. Sensitivity is higher when the nozzle electrode 6 and platinum electrode 15 are connected to the positive side of the high voltage power source.

Since the inside of the ionization chamber 7 is filled with a mixed gas of oxygen, nitrogen, helium, etc., the iridium electrode 15 can be heated in this state to obtain the iridium electrode 15 coated with iridium oxide. .

3 and 4 are chromatograms showing the sensitivity and selectivity for amine compounds and ammonia for the detector shown in FIG. 1,
The horizontal axis shows time (in minutes), and the vertical axis shows voltage (100 minutes).
The scale is 0.01 volt. ). The analysis conditions are as follows.

As the analysis sample, a 1.6μ solution of 10ppb tributylamine in acetone was used, and the column diameter was
A 2.6 mm, 2 m long glass column was used. The filler used was 80 to 100 meshes of Chromosol W coated with a 15% Apiezon L and 5.0% potassium hydroxide solution. Column temperature is 150
℃, and the detector temperature is 250℃. The range is 10 ¹⁰ Ω with 100 divisions and a full scale of 0.02.
In volts, the sensitivity is 2×10 ^-12 A.

In Figures 3 and 4, the peak of tri-n-butylamine (indicated by A in Figure 3 and C in Figure 4) and the peak of n-dodecane (indicated by D in Figure 4) ) appears clearly. Peak A of tri-n-butylamine in FIG. 3 corresponds to 16 pg of tri-n-butylamine. Also,
Peak C of tri-n-butylamine in Figure 4
corresponds to 160 pg of tri-n-butylamine, while peak D of n-dodecane corresponds to 11.6 pg of n-dodecane.
The selectivity is remarkable.

(f) Effects The method and apparatus for analyzing amine compounds and ammonia of the present invention uses heated materials having a high work function, such as iridium, its oxide, and a mixture of iridium and oxide, as electrodes. Positive ions of the amine compound and ammonia are generated on the surfaces of these electrodes. Therefore, by measuring this positive ion concentration, amine compounds and ammonia can be analyzed with high selectivity, high sensitivity, and good reproducibility, and ppb order amine compounds and ammonia can be easily analyzed. detection and reliable analysis.

Therefore, the method and apparatus for analyzing amine compounds and ammonia of the present invention can analyze, for example, ammonia, trimethylamine, etc., which are regulated by the Offensive Odor Prevention Law, in a single analysis operation, and can also perform a concentration operation. Simplified. Furthermore, the present invention
It can be used for the analysis of pollutants such as ammonia and amine compounds in water, and the highly sensitive analysis of amine compounds in biological samples.Moreover, the highly reliable analysis that has traditionally been required can be easily performed with simple operations. , has excellent practicality.

In addition, unlike conventional thermal ionization detectors, the method and apparatus for analyzing amine compounds and ammonia of the present invention do not use hydrogen gas, so the danger of hydrogen gas can be avoided, making it easy to carry out analysis operations. It's safe.

As described above, the amine compound and ammonia analysis method and apparatus of the present invention are superior to conventional analysis methods and apparatuses, and have a large influence.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing one embodiment of the present invention, and FIG. 2 is a schematic explanatory diagram showing another embodiment. FIGS. 3 and 4 are chromatograms showing the sensitivity and selectivity of the detector shown in FIG. 1 to amine compounds. Regarding the symbols, 1 is the detector, 2 is the separation column, 3 is the T-joint, 4 is the quartz nozzle, and 5
is an air supply pipe, 6 is an open end, 7 is an ionization chamber, 8
is a nozzle electrode, 9 is a high voltage power supply, 10 is an air supply port, 11 is a collector electrode, 12 is an inner collector electrode, 14 is an outer collector electrode, 15 is an iridium electrode, 16 is a transformer, 17 is a power controller, 18 is an electrometer and also A
and C are trimethylamine peaks and B and D are acetone solvent peaks.

Claims (1)

[Claims] 1. A mixed gas of an amine compound and/or ammonia analysis sample gas and an oxygen-containing gas is mixed with iridium (Ir), an oxide of iridium, or a metal having a higher work function than the heated sample. A method for analyzing amine compounds and/or ammonia, which comprises contacting a solid containing a combination of iridium and an oxide and measuring the ionization current of the decomposed gas. 2. An electrode connected to a heating power source, at least a portion of whose surface is made of iridium, iridium oxide, or a combination of iridium and oxide, which is a metal with a higher work function than the sample;
An amine compound and/or ammonia analyzer comprising: a nozzle facing the electrode; a sample gas and oxygen-containing gas flow path connected to the nozzle; and an ionization current measuring electrode.