JPH09145674A - Method and equipment for analyzing element of compound by gc/ms - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate determination of compound in the analysis employing GC/MS(gas chromatography/mass spectrometry). SOLUTION: Elution gas from a column 4 of gas chromatograph 2 is reduced by hydrogen gas and the elements of compound contained in the elution gas are converted into hydrides. The reduced elution gas is introduced to a mass spectrometer and ionized by EI method and peak of selected mass number characterizing each element is determined. Quality of each element and the ratio of content are then determined based on the peaks thus determined. Furthermore, the elution gas from a column 4 of gas chromatograph 2 is not passed through a reaction chamber but introduced directly to mass spectrometer and ionized by EI method thus determining mass spectrum. A data base is then retrieved based on the mass spectrum and several possible compounds are selected as candidates. Finally, the compound is specified by collating the qualitative results of elements obtained by analysis in the reaction chamber or the ratio of content.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a GC / MS in which a gas chromatograph (GC) and a mass spectrometer (MS) are directly connected.
An analysis method for performing qualitative analysis or further quantitative analysis of an organic compound by (gas chromatography / mass spectrometry);
The present invention relates to a GC / MS device therefor.

[0002]

2. Description of the Related Art In GC / MS, a mixture sample of organic compounds is separated by a gas chromatograph, an eluent gas of the gas chromatograph is guided to a mass spectrometer, and the separated components are qualitatively and quantitatively analyzed by the mass spectrum. For the qualitative analysis of the compound using GC / MS, He (helium) or the like is used as a carrier gas for the gas chromatograph, the unknown component separated and eluted by the column is introduced into the mass spectrometer, and the EI method (electron impact ionization) is used. Method) is used to obtain a mass spectrum, and from the mass spectrum, NIST or Wile is obtained.
Qualitatively using a database such as y. In the mass spectrometer, as another method, methane or isobutane, which is a reaction gas, is added to ionize the component molecules in the elution gas by the CI method (chemical ionization method) to obtain the molecular weight, and E
It is also performed to qualify unknown components together with the mass spectrum by the method I.

[0003]

Even if a search is made using a database of NIST or Wiley, there are many compounds having similar mass spectrum patterns, and the compounds cannot be identified in some cases. Therefore, in the present invention, P constituting an organic compound is
(Phosphorus), N (Nitrogen), O (Oxygen), F (Fluorine), S
The compound is specified by the presence or absence of the constituent elements such as (sulfur), Cl (chlorine) and Br (bromine), or by making it possible to analyze the constituent ratio of each element including C (carbon). The purpose is to facilitate.

[0004]

According to the analysis method of the present invention,
The elution gas from the column of the gas chromatograph is reduced with hydrogen to convert the constituent elements of the compound contained in the elution gas into hydrides, and the reduced elution gas is introduced into a mass spectrometer and ionized by the EI method. The peaks of the mass numbers selected to characterize each element are determined, and the qualitative or further content ratio of each element is determined based on these peaks.

The GC / MS apparatus of the present invention includes a reaction chamber for converting a constituent element of a compound into a hydride, a first channel for directly connecting a gas chromatograph column outlet to a mass spectrometer, and the reaction chamber. And a flow path switching means for switching the flow path to and from the second flow path connected to the mass spectrometer.

In the reaction chamber, the organic compound eluted from the column is reduced with hydrogen to produce N → NH ₃ , P → PH ₃ , O → H.
₂ O, C → CH ₄ , Cl → HCl, S → H ₂ S, F → H
Converted from F, Br to HBr. These hydrides are ionized by the EI method in a mass spectrometer to obtain a mass spectrum. In the mass spectrum, the mass number m / z (m is the mass of the ion, z is the number of charges) peculiar to each element is selected from the isotope ion and the molecular ion, and the presence or absence of each element or The content ratio of each element constituting the organic compound is calculated.

Further, the eluent gas from the column of the gas chromatograph is directly introduced into the mass spectrometer without passing through the reaction chamber and ionized by the EI method to obtain the mass spectrum. By searching the database based on this mass spectrum, some possible compounds are searched as candidates. With respect to the candidate compound, the compound is specified by comparing the qualitative results of the constituent elements and the content ratio results obtained by the analysis through the reaction chamber.

[0008]

EXAMPLE FIG. 1 schematically shows a GC / MS apparatus of an example. In the column oven surrounded by the broken line of the gas chromatograph unit 2, a sample injection unit 6 is arranged at the inlet of the separation column 4, and He as a carrier gas is used.
Is introduced into the separation column 4 from the sample injection part 6 via the pressure regulator 8.

A reaction chamber 10 is provided outside the column oven of the gas chromatograph section 2. Reaction chamber 10
Is a quartz tube filled with a palladium catalyst and heated to 500 to 1000 ° C., for example. When a mixed gas of an organic compound and hydrogen passes through the reaction chamber 10, the organic compound is reduced by hydrogen and converted into a hydride of an element forming the organic compound. H ₂ is introduced into the reaction chamber 10 as a reaction gas through the pressure regulator 12 and the resistance tube 14, and the flow path at the outlet of the separation column 4 is connected to the inlet of the reaction chamber 10 through the switching valve 16 and enters the reaction chamber 10. Is introduced by mixing hydrogen with the eluent gas from the separation column 4.
The outlet of the reaction chamber 10 is again introduced into the mass spectrometer via the switching valve 16.

The switching valve 16 is a first flow path shown by a solid line for directly connecting the outlet of the separation column 4 to the mass spectrometer, and a broken line for connecting the outlet of the separation column 4 to the mass spectrometer via the reaction chamber 10. The second flow path indicated by is switched. In the gas chromatograph unit 2, the sample injection unit 6, the separation column 4 and the switching valve 16 are arranged in the column oven and kept at a constant temperature. However, the switching valve 16 may be arranged in a heat insulation block whose temperature is adjusted outside the column oven.

The hydride of each element constituting the organic compound in the eluent gas reduced through the reaction chamber 10 is introduced into the mass spectrometer and ionized by the EI method. Among the mass spectra obtained there, the mass number m / z selected to characterize each element is, for example: Characterizing C ¹³ C ...... m / z = 13 N characterizing NH ₃ …… m / z = 17 When O is present, the peak of OH ion is also m / z = 1.
Appears in 7. Since the peak of m / z = 18 is only due to O, the intensity ratio of m / z of 17 and 18 is calculated in advance with H ₂ O, and the O content in the peak intensity of m / z = 17 is excluded. To correct. What characterizes O H ₂ O …… m / z = 18 What characterizes P P …… m / z = 31 PH ₃ …… m / z = 34 (when S does not exist) What characterizes S H ₂ S ... When m / z = 34 P is present, the PH ₃ ion peak is also m / z =
Appears at 34. Since the peak of m / z = 31 is only due to P, the intensity ratio of m / z of 31 and 34 is calculated in advance in PH ₃ , and the portion of P in the peak intensity of m / z = 34 is excluded. Correct to. Characterizing Cl H ³⁷ Cl …… m / z = 38 F characterizing HF …… m / z = 20 Br characterizing H ⁷⁹ Br …… m / z = 80 Peak position of these mass numbers Are collectively shown in FIG.

[0012]

INDUSTRIAL APPLICABILITY In the present invention, the elution gas from the column of the gas chromatograph is reduced with hydrogen to convert the constituent elements of the compound contained in the elution gas into hydrides, and the reduced elution gas is applied to the mass spectrometer. Introduced and ionized by the EI method, the peaks of the selected mass numbers are obtained to characterize each element, and the presence or absence of constituent elements such as N, P and O, and further C are included based on these peaks. Since the composition ratio can be obtained, the mass spectrum obtained by directly introducing the elution gas from the column into the mass spectrometer and ionizing it by the EI method can be used to search for similar spectra by using a database such as NSIT or Wiley. It is easy to identify the compound even when there are many. In addition, the mass spectrum obtained after reducing the eluent gas with hydrogen according to the present invention also provides information on the ratio of elements constituting the analytical compound, which is particularly useful information on the qualitative properties of the compound not included in the database.

[Brief description of the drawings]

FIG. 1 is a flow chart schematically showing the device of the present invention.

FIG. 2 is a diagram showing positions of peaks characterizing each element.

[Explanation of symbols]

 2 Gas chromatograph section 4 Column 6 Sample injection section 10 Reaction chamber

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location G01N 30/88 G01N 30/88 C

Claims (2)

[Claims] 1. A step of reducing the elution gas from a column of a gas chromatograph with hydrogen to convert the constituent elements of the compound contained in the elution gas into a hydride, and introducing the reduced elution gas into a mass spectrometer. And ionizing by the EI method to obtain a peak of a mass number selected to characterize each element, and a step of obtaining a qualitative or further content ratio of each element based on the peak. Elemental analysis method of compounds by MS. 2. In a GC / MS apparatus for introducing gas eluted from a column of a gas chromatograph into a mass spectrometer, a reaction chamber for converting constituent elements of a compound into a hydride and a column outlet of the gas chromatograph are connected to the mass spectrometer. A flow path switching means for switching the flow path between a first flow path directly connected and a second flow path connected to the mass spectrometer through the reaction chamber. / MS device.