Determination of hydrocarbon impurities in industrial ethylene by gas chromatography (3)

7 Instrument preparation

7.

Column temperature: initial temperature: 35℃; initial temperature retention time: 2.

Carrier gas: helium or nitrogen, 6mL/min～8mL/min

Split injection system: injection valve loop volume: 200uL～500uL, injection valve temperature: 35℃～45℃, split injector temperature: 150℃～200℃, split ratio: 50:1～100:1, FID temperature: 300°C, air: 300 mL/min, oxygen : 30 mL/min, makeup gas N ₂ , 20 mL/mnin

Sensitivity: Set at an appropriate value that can obtain the impurity measurement value

Splitless injection system: injection valve loop volume: 10uL～60uL, injection valve temperature: 35℃～45℃

Note: The heating of 1 Al ₂ O ₃ PLOT column should not exceed 200°C to prevent changes in column activity

2 The air and hydrogen flow parameters of FID can be determined according to the values ​​recommended by the instrument manufacturer

7.

Figure 5 Typical chromatogram

10 calculation

10.

c _i =f _i ×A _i .

In the formula: c _i — the concentration of impurity i in the sample, mL/m ³ ;

f _i — the correction factor of impurity i calculated by formula (1);

A _i —the peak area of ​​impurity i obtained by the integration of the data acquisition system

10.

11 Repeatability

In the same laboratory, the same operator uses the same instrument and equipment to perform two repeated measurements on the same sample.

The concentration of impurity components ≥10mL/m ³ , which is 10% of its average value;

The impurity component concentration is less than 10mL/m ³ , which is 15% of its average value

12 Report

The report should include the following:

a) with the Ministry of Information on the sample, such as the name of the sample, batch number, sampling sites, sampling date, sampling time

b) Code of this standard
.

c) Analyze the results
.

d) Details and descriptions of any abnormal phenomena observed in the measurement
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e) the name of the analyst and analysis date
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