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1 scope of application
1.1 this standard applies to the determination of total hydrocarbons in air.
1.2 the sample was collected by the method of sampling, and the gas chromatography with a hydrogen flame ionization detector was used to measure the gas phase. The sample was introduced into the detector and the content of the hydrocarbon was determined by the air column or glass beads.
1.3 detection range:
The apparatus used is different. The lower limit of total hydrocarbon was m / 0.14mg 3.
With nitrogen as the carrier gas for the determination of total hydrocarbon content in the air, total hydrocarbon peak oxygen consists of, because sample towel oxygen of response value have effect. Here, the hydrocarbon removal purification air holes for blank value. From the total hydrocarbon peak net oxygen group scores.
2 Definition
Total hydrocarbons (C1 ~ C8) measured by an oxygen flame detector is a total hydrocarbon, with methane.
3 reagents and materials
3.1 carrier gas and auxiliary gas
3.1.1 nitrogen: 999% pure nitrogen. Purification with 5A molecular sieve.
3.1.2 hydrogen: 999%. With silica gel and activated carbon purification pipe purification.
3.1.3 air: the use of a high pressure cylinder or a non oil air compressor gas supply, with silica gel and activated carbon purification.
3.1.4 purification of air: the purification of the removal of hydrocarbons in the air arm (see Appendix A).
3.2 reagents and materials used in the preparation of chromatographic columns
2.1 the relevant contents of the 4.3 column and the reference of the filling material of the column and the filler 3.
3 standards:.2.2 chromatography with nitrogen as the energy of 7 1mg / m3 (10 ppm) around the standard gas of methane
4 instrument
4.1 instruments: gas chromatography with hydrogen flame ionization detector.
4 1.1 instrument main components: equipped with a hydrogen flame ionization detector, incidental column heating furnace, temperature regulator into export heater, detector heater and the corresponding temperature regulator, amplifier and so on.
4.1.2 control of the pressure gauge, flow meter and auxiliary gas flow meter.
4.2 into the sample; the instrument comes with a stainless steel inlet or six way valve, ML l quantitative tube.
4.2.1 syringe; 1 ml, 5 ml, 50 ml, 100 mI syringe if 1.
4.3 column:
4.3.1 column type: an empty column or packed column.
4.3.2 column number: 2 ~ 3.
Characteristics of 4.3.3 column:
4.3.3.1 material: stainless steel.
4.3.3.2 length: 1 ~ 2m.
4.3.3.3: the diameter of phi 5mm
4.3.3.4 shape: spiral.
4.3. 4 filler
4 3 4.1 silanized glass beads or do not install any filler (empty columns).
4.3.2.4 granularity: 60~80.
4.3.5 filling method:
Stainless steel column end with a glass wool plug, connected to a vacuum pump; the column on the other end of the hose connected to the funnel, supported slowly through the funnel into the
Chromatographic column. At the same time, open the vacuum pump, and gently tap the column to fill in the column with a tight, uniform.
After the glass wool plug. In order to prevent the glass wool and the pump, the vacuum pump is connected with a capillary and a buffer between the vacuum pump and the column.
Bottle.
4.3. 6 chromatographic column:
Will fill good chromatographic column is the receiving apparatus inlet, the other end ungrounded detector, with low velocity (about 10 ml / min) of the carrier gas into and column temperature rise to 100 aging about 24 h, then the chromatographic column access chromatographic system, baseline to stay straight away so far.
4.4 detector: hydrogen flame ionization detector.
4.5 recorder: measuring range 5 ~ 10mV.
5 sample
5.1 sample properties
5.1.1 sample name: ambient air sample.
5.1.2 sample status: gas.
5.2 sampling and storage method
With 100 ml syringe in the breath of people with highly selected air samples to be tested, repeated replacement after three pumping to 100 samples of M1 with rubber cap seal head sent to a lab to be tested; on the day of the sample analysis is completed.
6 operation steps
6.1 adjustment instrument
6.1.1 vaporization chamber: 70 ~ 100.
6.1.2 column temperature: 70.
Flow rate of 6.1.3 carrier gas flow rate of hydrogen and air according to the specific circumstances of the instrument.
6.1.4 detector temperature: 50 "C.
6.1.5 recorder:
6.1.5.1 attenuation: according to the sample contained in the measurement of the concentration of the regulator to adjust the recording instrument.
6.1.5.2 paper speed: 5mm / mln.
6.2 calibration
6.2.1 external standard method
6.2.1.1 calibration: according to the stability of the instrument, generally in a batch of samples, can be in the beginning, the middle and the final calibration.
6.2.1.2 of standard samples of preparing standard gas of methane, within the linear range of the instrument with a syringe with nitrogen emboldened formulated a series of concentrations of standard gas.
The use of 6.2.2 standard sample
The sample volume of the 6.2.2.1 standard sample is the same as the sample sample volume, and the response value of the standard sample should be close to the sample.
6.2.2.2 uses the standard sample, requiring only a single peak.
6.3 test
6.3.1 sample
6.3.1.1 sampling method: using a syringe or plug into the sample.
6.3.1.2 sample size: M1 L.
6.3.1.3 operation: use the syringe to sample the test sample, after three times of repeated replacement, accurate extraction of 1 ml, rapid injection chromatography system
Study on 6.4 chromatogram
6.4.1 standard chromatogram see below.
6.5 quantitative analysis
6.5.1 chromatographic peak measurement
To peak at both the beginning and end of the contact line as peak to bottom, from a peak of high maximum perpendicular to the time axis. Corresponding time is the retention time. The line from peak to peak between the bottom of the line segment is high peak.
Representation of 7 Results
7.1 qualitative results
According to the retention of methane in the column, the volume of the sample is determined.
7.2 quantitative results
According to the calculating formula, the total hydrocarbon content in the sample is calculated.
8 precision and accuracy
5 laboratory analysis of Mg m3 / L.42 and 3