JP2012211802A - Method for analyzing sulfur compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for analyzing a sulfur compound that is capable of measuring the concentration of the sulfur compound contained in a sample gas quickly and accurately by using a flame photometric detector.SOLUTION: In a method for analyzing a sulfur compound that measures the concentration of the sulfur compound contained in a sample gas by using a flame photometric detector, a gas with the highest component concentration in the sample gas is used as a carrier gas. The carrier gas with the sample gas is directly introduced into the flame photometric detector 19 through a resistance tube 17 provided instead of a conventional separation column. The flow channel resistance of the resistance tube 17 is set higher than that of tubes located in front and back of a measuring tube and an introduction tube of the flame photometric detector 19.

Description

  The present invention relates to a method for analyzing a sulfur compound, and more particularly, to a method for analyzing a sulfur compound in which the concentration of a sulfur compound contained in a trace amount as an impurity in a sample gas is measured using a flame photometric detector.

  In the gas manufacturing field and semiconductor manufacturing field, there is an increasing need to measure the concentration of various impurities contained in a multicomponent mixed gas in a short time with high sensitivity. Conventional flame photometric detectors are detectors that selectively detect sulfur compounds and phosphorus compounds. Analysis of malodorous components such as hydrogen sulfide and methyl mercaptan, detection of trace sulfur in chemicals, residual It is widely used for the analysis of agricultural chemicals and biochemical components. A sulfur compound of several ppb level contained as an impurity in the mixed gas is analyzed with a flame photometric detector combined with a liquid nitrogen concentration system (see, for example, Patent Document 1).

JP 2002-250722 A

  However, when the sulfur gas in the pure gas is measured at the ppb level using the flame photometric detector, if the sample gas and the carrier gas are different, a peak derived from the carrier gas appears. For example, when measuring sulfur impurities in oxygen or argon, if nitrogen is used as the carrier gas, the peak of oxygen or argon appears on the chromatographic chart overlapping the peak of sulfur compounds, making accurate measurement difficult. In addition, if the flow rate of the carrier gas is lowered in order to separate both peaks, there is a problem that the time required for measurement becomes longer.

  Accordingly, an object of the present invention is to provide a method for analyzing a sulfur compound, which can quickly and accurately measure the concentration of a sulfur compound contained in a sample gas using a flame photometric detector.

  In order to achieve the above object, the sulfur compound analysis method of the present invention is a sulfur compound analysis method in which the concentration of a sulfur compound contained in a sample gas is measured using a flame photometric detector. A gas having the highest component concentration is used as a carrier gas.

  Furthermore, in the method for analyzing a sulfur compound of the present invention, after the sample gas is introduced into the measuring tube and measured, the carrier gas is introduced into the measuring tube and the measured sample gas is entrained in the carrier gas. It is characterized in that it is introduced into the flame photometric detector through a resistance pipe having a larger flow path resistance than pipes before and after the measuring pipe and an introduction pipe of the flame photometric detector. Further, the carrier gas is characterized in that one of a plurality of types of gases is switched and introduced in accordance with the type of sample gas and the state of the flame photometric detector.

  According to the sulfur compound analysis method of the present invention, the gas having the highest component concentration in the sample gas, that is, the main component gas is used as the carrier gas, and therefore when a gas different from the main component gas is used as the carrier gas. The problem can be solved and the influence of the main component gas can be eliminated, and the concentration of sulfur compounds can be measured with a flame photometric detector without the need for component separation using a separation column, which was essential in conventional analytical operations. Can do. Since the component separation is not performed, not only the operation time can be greatly shortened, but also the peak of the sulfur compound can be increased and the half-value width can be reduced, so that the detection lower limit can be improved.

It is explanatory drawing which shows an example of the analyzer which can implement the analysis method of the sulfur compound of this invention. It is explanatory drawing which shows an example of the conventional analyzer which uses a flame photometric detector. It is a figure which shows the result of Experimental example 1. FIG. It is a figure which shows the result of Experimental example 2. It is a figure which shows the result of Experimental example 3.

  First, as shown in FIG. 1, an analyzer capable of performing the sulfur compound analysis method of the present invention includes a sample gas introduction path 11, a first carrier gas introduction path 13 a and pressure regulators 12 a and 12 b, respectively. Second carrier gas introduction path 13b, carrier gas switch 14 for switching the carrier gas introduced into the apparatus, measuring tube 15 for measuring the sample gas, and hexagonal switching for switching the flow path of the sample gas and the carrier gas An analysis path 18 having a valve 16, a resistance tube 17, a flame photometric detector 19 and a measuring means 20 for analyzing a gas introduced from the analysis path 18, and an exhaust path 22 having a flow meter 21. Have.

  When measuring the concentration of sulfur compounds in the sample gas using a flame photometric detector, the pressure and flow rate of each gas are adjusted to preset values, and predetermined pretreatment (purging, temperature First, measure the sample gas in the state of adjustment. The six-way switching valve 16 is switched to the path indicated by the solid line in FIG. 1, and the sample gas introduced from the sample gas introduction path 11 to the analyzer passes through the path indicated by the solid line of the six-way switching valve 16 and passes through the measuring tube 15. Then, the gas again passes through the six-way switching valve 16, passes through the flow meter 21, and is discharged from the exhaust path 22. At this time, the carrier gas selected by the carrier gas switch 14 enters the six-way switching valve 16 from the first carrier gas introduction path 13a or the second carrier gas introduction path 13b, flows out into the analysis path 18 and flows through the resistance tube 17. As described above, it is introduced into the flame photometric detector 19.

  After sufficiently flowing the sample gas through the measuring tube 15 and replacing the inside of the measuring tube 15 with the sample gas, the hexagonal switching valve 16 is switched to the path indicated by the broken line in FIG. 1, and the sample gas measured by the measuring tube 15 is transferred to the carrier. The gas is introduced into the flame photometric detector 19 along with the gas. That is, the carrier gas introduced into the six-way switching valve 16 through the carrier gas switching device 14 passes through the path indicated by the broken line of the six-way switching valve 16, accompanies the sample gas through the measuring tube 15, and again is the six-way switching valve. 16 through the resistance tube 17 of the analysis path 18 and introduced into the flame photometric detector 19. On the other hand, the sample gas introduced from the sample gas introduction path 11 passes through the path indicated by the broken line of the six-way switching valve 16 and is discharged from the exhaust path 22 through the flow meter 21.

  At this time, a gas having the highest component concentration among the components in the sample gas, that is, a main component gas is used as the carrier gas accompanying the sample gas. For example, when the main component of the sample gas is argon, argon is used as the carrier gas, and when the main component of the sample gas is oxygen, oxygen is used as the carrier gas. In the case of a mixed gas in which a plurality of types of gases are mixed, the gas having the highest component concentration among the components in the mixed gas is selected as the carrier gas.

  The resistance pipe 17 has a flow resistance set larger than that of the pipe before and after the measuring pipe 15 and the introduction pipe of the flame photometric detector 19, that is, the pipe of the analysis path 18, and is, for example, an orifice. Or a moderately long tubule can be used. The sample gas measured by the measuring tube 15 and entrained by the carrier gas passes through the resistance tube 17 having a large flow path resistance, and is introduced into the flame photometric detector 19 in a state where the gas flow is stabilized. That is, the sample gas entrained by the carrier gas is introduced directly from the measuring tube 15 into the flame photometric detector 19 by stabilizing the gas flow with the resistance tube 17 without performing conventional component separation. Is done.

  Further, it is preferable to use a multi-position valve as described in JP-A-2001-4100, for example, as the carrier gas switch 14. In other words, the multi-position valve can continuously flow at a small flow rate without retaining the gas in each switching channel in the valve, so it can be switched using multiple carrier gases of different types. In this case, it is possible to prevent the carrier gas from staying around the valve, and to avoid adverse effects due to the staying of the gas. Furthermore, the multi-position valve can also switch and supply 10 or more types of carrier gas, and can efficiently supply a carrier gas suitable for each sample gas when analyzing various sample gases.

  On the other hand, in the conventional analyzer shown in FIG. 2, a separation column (capillary column) 31 for separating components in the passing gas is provided in the analysis path 18 instead of the resistance tube. Further, the carrier gas is provided with only one system of the carrier gas introduction path 13 provided with the pressure regulator 12. In FIG. 2, the same components as those of the analyzer shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The separation column 31 separates each component in the sample gas, and is a long column filled with a sulfur compound to be measured and other components, particularly a filler for separating the sulfur compound and the main component gas. It has a flow path. Generally, when component separation is performed in the separation column 31, it is difficult to perform sufficient component separation if the flow rate of the carrier gas is high. To sufficiently perform component separation, the flow rate of the carrier gas is decreased. There is a need. Therefore, if the carrier gas flow rate is increased in order to shorten the measurement time, the component separation cannot be sufficiently performed, and if the carrier gas flow rate is decreased in order to sufficiently perform the component separation, there is a problem that the measurement time becomes longer.

Experimental example 1
An experiment was conducted to analyze a sulfur compound (concentration 1 ppm) contained in argon using the conventional analyzer shown in FIG. Nitrogen was used as the carrier gas, and the flow rate of the carrier gas was 40 ml / min. As a result, as shown in FIG. 3, the peak of nitrogen as the carrier gas and the peak of the sulfur compound overlapped and accurate analysis could not be performed.

Experimental example 2
The same procedure as in Experimental Example 1 was performed except that the flow rate of the carrier gas was 20 ml / min. As a result, as shown in FIG. 4, the peak of nitrogen as the carrier gas and the peak of the sulfur compound were separated, but the measurement time was extended about twice.

Experimental Example 3 (Example of the present invention)
The apparatus shown in FIG. 1 was used, argon was used as the carrier gas, and the flow rate was 40 ml / min. As a result, as shown in FIG. 5, only the peak of the sulfur compound could be obtained. Moreover, the measurement time could be shortened to about a half compared with Experimental Example 2.

  DESCRIPTION OF SYMBOLS 11 ... Sample gas introduction path, 12, 12a, 12b ... Pressure regulator, 13, 13a, 13b ... Carrier gas introduction path, 14 ... Carrier gas switch, 15 ... Metering pipe, 16 ... Six-way switch valve, 17 ... Resistance pipe , 18 ... analysis path, 19 ... flame photometric detector, 20 ... measuring means, 21 ... flow meter, 22 ... exhaust path, 31 ... separation column

Claims (3)

  In a sulfur compound analysis method for measuring the concentration of a sulfur compound contained in a sample gas using a flame photometric detector, the sulfur compound analysis method using a gas having the highest component concentration in the sample gas as a carrier gas .   After the sample gas is introduced into the metering tube and weighed, the carrier gas is introduced into the metering tube and the sample gas measured is entrained with the carrier gas, and the pipes before and after the metering tube and the flame photometric detection The sulfur compound analysis method according to claim 1, wherein the flame photometric detector is introduced into the flame photometric detector through a resistance pipe having a flow passage resistance larger than that of the introduction pipe of the vessel.   The sulfur carrier analysis method according to claim 1 or 2, wherein the carrier gas is introduced by switching one of a plurality of types of gases according to the type of sample gas and the state of the flame photometric detector.

Images