JPH09243602A - Structural analysis of azo compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the structural analysis of an azo compd. slightly soluble in an org. solvent within a short time by using a small amt. of a sample. SOLUTION: A very small amt. of an azo compd. is rapidly heated to predetermined temp. to be pyrolyzed and the generated pyrolyzed product is directly introduced into the lonizing chamber of a mass analyser by directly connecting a sample cell to the ionizing chamber 4a of the mass analyser 4. This apparatus is constituted of a heating probe 2, a sample cell 2a housing a sample and an ion detector. The azo compd. is rapidly heated by subjecting the azo compd. wrapped in ferromagnetic metal foil to high frequency induction heating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for analyzing the structure of an azo compound which is sparingly soluble in an organic solvent used for an electrophotographic organic photoreceptor or the like.

[0002]

2. Description of the Related Art Azo compounds are used not only as pigments but also in organic photoconductors for electrophotography, and their structural analysis is important. However, many azo compounds are difficult to dissolve in an organic solvent, and the nuclear magnetic resonance analysis cannot be applied to these compounds. Therefore, as a structural analysis method, an infrared spectroscopic analysis method, a mass spectrometry method using a chemical ionization method, a chemical reductive decomposition method, or the like has been applied, but detailed structural analysis thereof has been difficult.

Since infrared spectroscopic analysis can obtain only functional group information, it is effective only for the analysis of a specific limited partial structure. In mass spectrometry, sample decomposition and ionization methods are important. The chemical ionization method suppresses decomposition and ionizes the entire sample molecule, so it is difficult to obtain partial structural information. Since the chemical reductive decomposition method chemically decomposes the sample, it is possible to obtain various kinds of decomposition products, but on the other hand, the amount required for one sample is large and the reactivity of the sample is different, so the decomposition conditions are different. A large number of samples and a long time are required for the optimization study.

[0004]

As a relatively simple structural analysis method, there is a pyrolysis gas chromatography / mass spectrometry method. Figure 5 shows conventional pyrolysis gas chromatography /
It is a schematic diagram of a mass spectrometer. The sample S placed in the pyrolysis probe 2 is instantly pyrolyzed. The thermal decomposition product is sent to the capillary column 3 together with a carrier gas (a supply circuit is not shown), and reaches the detector 4b which is the ionization chamber 4a of the mass spectrometer section 4 with a time lag due to the capillary column.

This structural analysis method is generally suitable for obtaining partial structural information if the pyrolysis temperature and the selection of the capillary column are appropriate. However, setting conditions for separating decomposition products in gas chromatography is complicated, and it is necessary to try several times, which requires time.
In addition, decomposition products may be trapped during gas chromatography, not introduced into the mass spectrometer, and may not be detected.

The present invention has been made in view of the above problems, and provides a method for carrying out structural analysis of an azo compound which is hardly soluble in an organic solvent in a short time using a small amount of sample.

[0007]

In order to achieve the above object, the structure analysis method for an azo compound according to the present invention is a method in which a trace amount of an azo compound in a sample cell is rapidly heated to a predetermined temperature to cause thermal decomposition and is generated. The thermal decomposition product will be directly introduced into the ionization chamber of the mass spectrometer by directly connecting it to the ionization chamber.

The rapid heating of the azo compound is based on high frequency induction heating of a small piece made of a ferromagnetic metal that wraps the azo compound inside. The small piece of ferromagnetic metal is preferably a foil having a roughened surface. The small pieces of the ferromagnetic metal are preferably formed by molding a foil into a boat, putting a sample, and then crushing the foil.

[0009]

1 is a schematic diagram of a direct pyrolysis mass spectrometer according to the present invention. A sample cell 2a attached to the tip of the pyrolysis probe 2 is directly connected to the ionization chamber 4a of the mass spectrometer 4. In such an apparatus, the thermal decomposition product from the azo compound sample that is sparingly soluble in the thermally decomposed organic solvent is adsorbed or given no time to cause a secondary reaction, and is introduced into the ionization chamber 4a and immediately It is ionized and reaches the detector 4c through the quadrupole electrode 4b for mass spectrometry. Therefore, if the thermal decomposition temperature and the thermal decomposition time are appropriate (not limited to one temperature), the groups constituting the sample molecule can be obtained as a thermal decomposition product. Accurate structural analysis is possible.

As a thermal decomposition method of an azo compound which is hardly soluble in an organic solvent, it is not necessary to dissolve the sample in the solvent, and the induction heating method is most suitable in terms of a steep temperature rise and the accuracy of the set temperature. . The induction heating method is a method in which a small amount of a sample is wrapped in a ferromagnetic metal foil having a Curie temperature of room temperature or higher so as not to scatter during heating, and the foil is subjected to high frequency induction heating.
The disappearance of ferromagnetism at the Curie temperature keeps the foil temperature exactly at the Curie temperature. Ferromagnetic metal is F
e, Ni, Co, or Cr, which is a simple substance or an alloy of 2 to 3 types, and the Curie temperature is different depending on the composition.

Further, in order to prevent the sample from being scattered when the sample is wrapped, it is effective to form fine irregularities on the foil surface or preform the foil into a boat shape or a test tube shape. Example 1 In this example, in order to confirm the method for structural analysis according to the present invention, a well-known azo compound chlorodian blue having a structure represented by the following formula was used.

[0012]

Embedded image

FIG. 2 shows a procedure for wrapping the azo compound. (A) is a state in which the sample S is placed on the ferromagnetic foil 5 having the rough surface 5a, (b) is a state in which the foil is folded back on the sample S, and (c) is a state in which the foil is further wound twice. Is. 2 μg of this azo compound is weighed to form a sample S, which is about 1 × 5 m
It was wrapped in a ferromagnetic foil 5 of m and 50 μm in thickness. Since the rough surface 5a was prepared by rubbing the surface of the foil wrapping the sample with diamond file in advance, the sample powder did not scatter during the wrapping operation.

The foil 5b enclosing the sample was placed in a quartz sample cell (see FIG. 1) and the sample cell was placed in a high frequency coil. The clearest m / z at a Curie temperature of 590 ° C
(M is the molecular weight of the detected ion, z is the valence of the ion) is 20
Zero or more signals were detected. FIG. 3 is a mass spectrometry spectrum of the azo compounds of Examples according to the present invention. m / z =
237, 252, 263, 278 lines a, b, c,
And d are respectively the following structural formulas (1), (2),
It was confirmed that it corresponds to the constituent molecular ions of the azo compound represented by (3) and (4).

[0015]

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Example 2 FIG. 4 is a view of a sample-covered boat according to the present invention during molding. (A) is a front view of a molding die, (b) is a perspective view of a boat. The ferromagnetic foil 5 was molded into a boat shape using a stainless steel lower mold 6a and an upper mold 6b, and then the azo compound sample was weighed and the side surface of the boat was crushed to wrap the sample. After that, mass spectrometry was performed in the same manner as in Example 1, but exactly the same mass spectrometry spectrum was obtained. In this example, it was not necessary to fold the ferromagnetic foil, the wrapping of the sample was easier than the simple sheet shape, and the sample was not scattered.

[0017]

According to the present invention, the structure analysis method for an azo compound is carried out by rapidly heating a small amount of the azo compound to a predetermined temperature for thermal decomposition, and the thermal decomposition product is stored in a sample cell in an ionization chamber of a mass spectrometer. Since it was introduced directly into the ionization chamber of the mass spectrometer by directly connecting to, the pyrolysis products from the pyrolyzed sample could not be adsorbed or given a time to cause a secondary reaction, resulting in ionization. Introduced into the chamber, immediately ionized and mass analyzed. Therefore, if the pyrolysis temperature and the pyrolysis time are appropriate (not necessarily 1 temperature),
The groups constituting the sample molecule are obtained as a thermal decomposition product, which enables accurate structural analysis.

Further, since the rapid heating of the azo compound is performed by the high frequency induction heating of a small piece made of a ferromagnetic metal which wraps the azo compound inside, the sample temperature has high accuracy and reproducibility, and the same constituent molecules are It is obtained as the same thermal decomposition product and has high identification. Further, since the surface of the small piece of the ferromagnetic metal is roughened or boat-shaped,
Dispersion of the sample after weighing can be prevented, and structural analysis can be performed with good stability.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a direct pyrolysis mass spectrometer according to the present invention.

FIG. 2 is a procedure for wrapping an azo compound, (a) rough surface 5a
Showing a state in which the sample S is placed on the ferromagnetic foil 5 having, (b) a state in which the foil is folded back on the sample S, and (c) a state in which it is further wound twice.

FIG. 3 is a diagram showing a mass spectrometry spectrum of an azo compound of an example according to the present invention.

FIG. 4 is a diagram at the time of molding the sample-covered boat according to the present invention,
(A) Front view of molding die, (b) Perspective view of boat

FIG. 5 is a schematic diagram of a conventional pyrolysis chromatography / mass spectrometer.

[Explanation of symbols]

 1 Gas Chromatography 2 Heating Probe 2a Sample Cell 2c High Frequency Coil 3 Capillary Column 4 Mass Spectrometer 4a Ionization Chamber 4b Quadrupole Electrode 4c Detecting Part 5 Ferromagnetic Foil 5a Rough Surface 5b Sample Enveloping State 5c Boat Ferromagnetic 6a Upper mold 6b Lower mold

Claims (4)

[Claims] 1. A azo compound that is sparingly soluble in a trace amount of an organic solvent in a sample cell is rapidly heated to a predetermined temperature for thermal decomposition, and the resulting thermal decomposition product is transferred to the ionization chamber of the mass spectrometer. A structure analysis method for an azo compound, which is characterized in that the azo compound is directly introduced into the ionization chamber by direct connection. 2. The method for analyzing the structure of an azo compound according to claim 1, wherein the rapid heating of the azo compound is performed by high frequency induction heating of a small piece made of a ferromagnetic metal that wraps the azo compound inside. 3. The method for analyzing the structure of an azo compound according to claim 2, wherein the small piece of the ferromagnetic metal is a foil having a roughened surface. 4. The method for analyzing the structure of an azo compound according to claim 2, wherein the small pieces of the ferromagnetic metal are formed by molding a foil into a boat shape, inserting a sample and then crushing the foil.