This method is suitable for the determination of trace nitrogen in electronic grade argon. This method can be used to simultaneously determine the content of methane, carbon monoxide and carbon dioxide. The determination range is 0.5-50ppm. SJ 2804.2-1987 Determination of trace nitrogen in electronic grade argon - variable temperature concentration chromatography (II) SJ2804.2-1987 Standard download decompression password: www.bzxz.net
This method is suitable for the determination of trace nitrogen in electronic grade argon. This method can be used to simultaneously determine the content of methane, carbon monoxide and carbon dioxide. The determination range is 0.5-50ppm.

Standard of the Ministry of Electronic Industry of the People's Republic of China Determination of trace nitrogen in electronic grade nitrogen
Variable temperature concentration chromatography (II)
SJ2804.2--87
This method is suitable for the determination of trace nitrogen in electronic grade nitrogen. This method can be used to simultaneously determine the content of methane, carbon monoxide and carbon dioxide. The determination range is 0.5~50ppm. 1 Principle of the method
1.1 This method is variable temperature concentration chromatography. The carrier gas carries the sample through the chromatographic column to separate the components, and then enters the thermal conductivity detector.
1.2 The thermal conductivity detector is made based on the principle that the thermal conductivity of other components mixed in the carrier gas changes. When the sample and the carrier gas enter the thermal conductivity cell together, due to the difference in thermal conductivity between the two, the temperature of the thermistor changes, causing its resistance to change accordingly, and the output signal is measured by the Wheatstone bridge.
1.3 This method uses a concentration technique to improve sensitivity, that is, under low temperature conditions, impurities are enriched on the concentrator to increase the injection amount. The molecular sieve has a large adsorption capacity for nitrogen at a temperature of about 80°C, but it also adsorbs a large amount of argon. In order to avoid the nitrogen chromatographic peak covering the nitrogen chromatographic peak, ultrapure hydrogen is used to purge a large amount of hydrogen in the concentrator before injection to separate the nitrogen peak.
1.4 Chromatographic analysis can use nitrogen as a carrier gas. Ultrapure hydrogen is highly sensitive, but the nitrogen in the concentrator needs to be purged before injection.
2 Instruments and materials
2.1 Gas chromatograph
Thermal conductivity detector;
Chromatographic column: stainless steel tube with an inner diameter of 4mm and a length of 2~3m; chromatographic column filler: 5A molecular sieve, 40~60 days; recorder or microprocessor: 0~1mV.
2.2 Carrier gas: Hydrogen comes from an ultrapure hydrogen generator, with a purity of 99.9999% and impurity N2 <0.01ppm. 2.3 Four-way piston concentrator: Glass or metal samplers can be used, the piston must be airtight, and the inlet and outlet ends must be connected to the gas path with ground joints or hard connections.
2.4 Wet gas flowmeter.
2.5 Cold source: dry ice + alcohol.
3 Flow chart and test conditions
3.1 See Figure 1 for the flow chart.
Sampler
Chromatographic column
Recorder
Calibrator
Flow chart for determination of trace nitrogen in electronic grade argon
Issued by the Ministry of Electronics Industry on May 18, 1987
Implemented on January 1, 1988
3.2 Test conditions
Bridge flow: 180~200A
Carrier gas: hydrogen, flow rate 40260m1/min
Attenuation: 1:
Column temperature: room temperature 15~35C.
Operation steps
SJ2804.2--87
A: Sample gas cylinder
B: Needle valve
C. Four-way piston concentrator sampling tube
D, cold source
E: Wet gas flowmeter
Figure 4 Diagram of the device for blowing off fluorine in the sampler
4.1 Purge gas circuit According to Figure 2, use a hard connection or ground connection system, and close the concentrator. Open the argon gas cylinder, the flow rate is about 800ml/min, and the time is about half an hour. Reduce the flow rate to about 500ml/min, open the four-way piston (see Figure 3), and let the argon gas pass through the molecular sieve in the sampler to purge the air in it, and the time is about half an hour. Further adjust the flow rate to about 200m1/min.
4.2 Sampling Slowly put on the cold source (dry ice and alcohol are mixed into a shed shape), start counting time, when the wet gas flow meter indicates that the gas volume reaches the requirement, turn off the gas source, and remove the cold source at the same time, when the gas volume discharged from the sampling tube is about 100m1. Immediately close the piston and remove the sampling tube.
4.3 Purge the fluorine gas According to Figure 4, use a hard connection or ground connection system (change the end of the concentrator connected to the argon cylinder to connect to the hydrogen cylinder) to close the sampling concentrator tube, purge the air in the gas path, the hydrogen flow rate is about 1000m1/m1n, the time is 3 to 5min, adjust the flow rate to about 100m1/min, open the sampling concentrator tube piston, purge the argon gas in it, the time is about 5 days, close the piston, and remove the cold source. 2
Quartz cloth
Molecular sieve
SJ2804.2-87
Figure 3 Four-way piston concentration sampling tube
Variable temperature concentration sampling device
Quartz cloth
Molecular sieve
A. Ultrapure hydrogen cylinder
B, needle valve
C, four-way piston concentration sampling tube
D: Cold source
E, soap foam flowmeter
SJ2804.2--87
4.4 Injection Place the concentrator in room temperature water or a hair dryer for 3 to 5 minutes, connect the concentrator to the chromatograph injection port with a hard connection, exhaust the air peak first, open the four-way piston of the concentrator tube for injection, wait for the sample peak to be emitted, and use a micro-injector to inject air as a standard sample.
5 Calculation results
Nitrogen content in argon-
Where:
A2-×79%×V/×
Assume that the peak area of ​​nitrogen in the standard air sample is A1, mm2, the volume of the standard air sample is V1, μ1;
the total volume of the sample is V, 1;
the peak area of ​​nitrogen in the sample is A2, mm2
The constant 79% is the percentage of nitrogen in the air. Analysis precisionbZxz.net
The arithmetic mean of three parallel determinations is the determination result, and the relative deviation is not more than ±15%. Test report
7.1 The test report should include the following contents:
time, place, unit, date
b, sampling method and number;
type and model of instrument used;
test conditions and results;
e. Analyst's signature.
Notes
8.1 The argon peak in the chromatographic peak is larger than the nitrogen peak, which is easy to cover the peak. Therefore, the chromatographic peak must be well activated. The activation conditions are: hydrogen flow rate of 50m1/min, furnace temperature of about 200℃, and activation for 12h. 8.2 The adsorbent should be activated during sampling. The activation conditions are nitrogen flow rate of 60m1/min, activation at about 200℃ for 7-8h, until there is no moisture on the tube wall.
8.3 The argon cylinder must be adjusted with a needle valve, otherwise the dead volume is large and the gas path is not easy to purge clean. 8.4 The system must be hard-connected or ground-jointed to prevent leakage. The ground-joint and four-way piston must be sealed with grease such as silicone grease and tightly matched.
9Typical chromatogram
Additional instructions:
See Figure 5.
SJ2804.287
5mm/min
Typical chromatogram for determination of trace nitrogen in electronic grade argon This standard was proposed by the Clean Technology Society of the Chinese Institute of Electronics. It is sponsored by the Standardization Institute of the Ministry of Electronics Industry. This standard was drafted and revised by Xing Yuying and Zhang Jun of the 878th Factory of the Ministry of Electronics Industry, Zhao Changchun of the Standardization Institute of the Ministry of Electronics Industry, and Yin Enhua of the Institute of Semiconductors of the Chinese Academy of Sciences. 5
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