GB/T 33646-2017 English PDF (GBT33646-2017)

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GB/T 33646-2017: Determination of the ester compounds in motor gasoline -- Gas chromatography
GB/T 33646-2017
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 75.160.20
E 31
Determination of Ester Compounds
in Motor Gasoline – Gas Chromatography
ISSUED ON. MAY 12, 2017
IMPLEMENTED ON. DECEMBER 1, 2017
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of PRC.
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Table of Contents
Foreword ... 3
Introduction ... 4
1 Scope ... 5
2 Normative References ... 5
3 Terms and Definitions ... 6
4 Method Summary ... 6
5 Reagents and Materials ... 6
6 Apparatus ... 7
7 Sampling ... 8
8 Test Procedures ... 8
9 Result Calculation ... 9
10 Precision ... 10
11 Quality Assurance and Control ... 10
12 Test Report ... 11
Appendix A (Normative) Establishment of Valve Blowback System and
Instrument Parameters ... 12
Appendix B (Informative) Chromatogram of Ester Compounds in Motor
Gasoline ... 15
Foreword
This Standard was drafted as per the rules specified in GB/T 1.1-2009.
This Standard was proposed by and under the jurisdiction of National
Technical Committee for Standardization of Petroleum Products and Lubricants
(SAC/TC 280).
Drafting organizations of this Standard. Shenzhen Institute of Measurement and
Quality Testing, PetroChina Petrochemical Research Institute, CNOOC Refinery Co.,
Ltd., and National Petroleum Products Quality Supervision and Inspection Center.
Chief drafting staffs of this Standard. Zhao Yan, Wang Lin, Xu Dongyu, Ji Ming, Zhang
Shiyuan, Huang Weilin, OuYang Kechuan, Lv Huanming, and Li Dong.
Determination of Ester Compounds
in Motor Gasoline – Gas Chromatography
Warning – personnel using this Standard shall have practical working
experience in the formal laboratory. The use of this Standard may involve certain
hazardous materials, equipment and operation; this Standard doesn’t address
all possible safety issues. The users shall be responsible for taking appropriate
safety and health measures, and ensure compliance with the conditions
stipulated in the relevant national regulations.
1 Scope
This Standard specifies the determination method of ester compounds (ethyl acetate,
sec-butyl acetate, dimethyl carbonate) in the motor gasoline.
This Standard is applicable to determine the motor gasoline, ester compounds with
concentration of 50mg/L ~ 2000mg/L; this Method can also determine beyond such
content range; however, the precision is not investigated.
This Standard is not applicable to alcohol-containing gasoline; Certain alcoholic
compounds (such as methanol, ethanol, tert-amyl alcohol, and sec-butanol) and
ketone compounds (such as acetone and butanone) may interfere the determination
of ester compounds.
2 Normative References
The following documents are essential to the application of this document. For the
dated documents, only the versions with the dates indicated are applicable to this
document; for the undated documents, only the latest version (including all the
amendments) are applicable to this document.
GB/T 1884 Crude Petroleum and Liquid Petroleum Products - Laboratory
Determination of Density - Hydrometer Method
GB/T 1885 Petroleum Measurement Tables
GB/T 4756 Method for Manual Sampling of Petroleum Liquids
GB/T 6683 Petroleum Products - Determination of Precision Data in relation to
Methods of Test
6.4 Electronic balance. accurate to 0.0001g.
6.5 Volumetric flask. 100mL.
6.6 Sample flask. small glass flask covered with gland or threaded buckle cap, and
there is a rubber gasket with polytetrafluoroethylene outer surface in the cap.
6.7 Pipette. 0.5mL, 1.0mL, 2.0mL, 5.0mL.
7 Sampling
7.1 Sampling shall be performed as per GB/T 4756 or other equivalent method.
7.2 Since the laboratory receives the sample, the original container shall be cooled
and stored at 0°C~5°C before sampling of any sub-samples.
7.3 If necessary, transfer the cooling sample into the pressure-sealed container, store
at 0°C~5°C till analysis is required.
8 Test Procedures
8.1 Gas chromatographic conditions
If different instruments are used, then the optimal analysis conditions may be different;
thus, it is impossible to give the general parameters for the gas chromatographic
analysis. The setting parameters shall ensure the to-be-tested components to be
separated and tested effectively. The parameters given in Appendix A are proven to be
feasible.
8.2 Sample injection
Directly take about 1.5mL of sample and place it into 2.0mL sample flask (6.6);
manually or take autosampler to inject 1.0µL specimen into gas chromatograph (6.1);
perform the chromatographic analysis according to the optimized method conditions.
If the content of ester compounds in the sample exceeds the test range specified in
Clause 1, the sample shall be suitably diluted (for instance, isooctane – xylene solution
with volume ratio of 5.1).
8.3 Qualitative analysis
Test the standard working solution (5.5) and specimen under the same instrument
analysis conditions; perform the qualitative analysis according to the retention time of
ester compounds chromatographic peak. The reference retention time of 3 kinds of
ester compounds can refer to Appendix B.
Appendix A
(Normative)
Establishment of Valve Blowback
System and Instrument Parameters
A.1 Establishment of valve blowback column system
A.1.1 Adjust the valve to the positive blow position (1 in Figure A.1); adjust the
flowrate to control Valve A, so that the flowrate can reach the setting value in Table A.1.
Measure the flowrate on the detector exit sample side.
A.1.2 Adjust the valve to the blowback position (2 in Figure A.1); measure the
flowrate on the detector exit sample side. If compared with flowrate in Table A.1, the
flowrate changes; adjust the flowrate control valve B, so that the flowrate is changed
within ±1mL/min.
A.1.3 Switch the valve from the positive blow position to the blowback position for
several times; observe the baseline; The change in pressure caused by initially
switching of the valve shall not generate the change or drift of the baseline. If baseline
changes, slightly adjust the flow control valve B, so that the baseline is stable.
A.2 Determination of blowback time
Prepare the n-nonane solution containing n-octane with volume ratio of 5%. Under the
positive blow state, inject 1µL of such solution into the system. Record the
chromatogram until the n-nonane flows out, the recorder pen returns to the baseline.
Measure the time from the sample injection to the recorder pen returns to the baseline
between the n-octane and n-nonane peak, in seconds. At this point, the n-octane has
flowed out, while the n-nonane has not. Half of such measurement time can be
approximated as “blowback time”, and shall be slightly adjusted within 30s~60s.
Repeat the above operation including the sample injection, switch to blowback state
according to the above determined “blowback time”. Then obtain the n-octane
chromatogram, while the n-nonane peak is very small or invisible in the chromatogram.
If necessary, do the further test, adjust “blowback time” till all n-octane peaks appear;
there is very small or no n-nonane peak. The “blowback time” obtained through actual
valve operation is required to be used in all the following calibration and analysis.
A.3 Instrument conditional pa...