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Basic data
| Standard ID | SN/T 5270-2019 (SN/T5270-2019) |
| Description (Translated English) | (Rubber and its products. Determination of ethylene thiourea. High performance liquid chromatography) |
| Sector / Industry | Commodity Inspection Standard (Recommended) |
| Classification of Chinese Standard | G70 |
| Classification of International Standard | 71.040.99 |
| Word Count Estimation | 7,793 |
| Date of Issue | 2019 |
| Date of Implementation | 2020-07-01 |
| Issuing agency(ies) | General Administration of Customs |
SN/T 5270-2019: (Rubber and its products. Determination of ethylene thiourea. High performance liquid chromatography)
---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Determination of ethylene thiourea in rubber and rubber products-High performance liquid chromatography
The People's Republic of China Entry-Exit Inspection and Quarantine Industry Standards
Issued by the General Administration of Customs of the People's Republic of China
2019-12-27 release
2020-07-01 Implementation
Rubber and its products. Determination of ethylene thiourea. High performance liquid chromatography
Foreword
This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This standard was proposed and managed by the General Administration of Customs of the People's Republic of China.
Drafting organizations of this standard. Fuzhou Customs of the People's Republic of China and Ningbo Customs of the People's Republic of China.
The main drafters of this standard. Ding Liping, Zheng Xiangping, Chen Minshi, Liu Zhengcai, Cai Chunping.
Determination of ethylene thiourea in rubber and its products
High performance liquid chromatography
1 Scope
This standard specifies the high performance liquid chromatography method for the determination of ethylene thiourea content in rubber and its products.
This standard applies to the determination of ethylene thiourea in rubber and its products.
The lower limit of the determination of ethylene thiourea in this standard is 2.0 mg/kg.
2 Normative references
The following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this article
Pieces. For undated reference documents, the latest version (including all amendments) is applicable to this document.
GB/T 6682 Analytical laboratory water specifications and test methods
3 Method summary
Ethylene thiourea in rubber and its products is ultrasonically extracted with methanol, and the extract is concentrated and purified by solid phase extraction.
Measured by spectrometer and quantified by external standard method.
4 Reagents and materials
Unless otherwise specified, the reagents used in this standard are all analytical reagents or higher, and the water is first-grade water that meets the requirements of GB/T 6682.
4.1 Acetonitrile. chromatographically pure.
4.2 Methanol.
4.3 Ethylene thiourea (ETU for short, CAS number. 96-45-7, molecular formula. C3H6N2S). The purity is greater than
98.0%.
4.4 Tert-Butyl-4-hydroxyanisole (BHA). The purity is greater than 99.9%.
4.5 Ethylene thiourea standard stock solution. accurately weigh an appropriate amount of standard substance, dissolve it with acetonitrile solvent, and prepare it to a concentration of 1000.0 mg/L
The standard stock solution is stored in a refrigerator at -4 ℃ for 2 months.
4.6 BHA solution (10.0 g/L). Dissolve 1.0 g of BHA in a small amount of methanol, and dilute to 100 mL for use.
4.7 Mobile phase. acetonitrile. water = 30.70, volume ratio, ready to use.
4.8 Solid phase extraction column. N-propyl ethylene diamine (PSA) cartridge, 500 mg/6 mL.
5 Apparatus and equipment
5.1 High performance liquid chromatograph. equipped with diode array detector.
5.2 Analytical balance. Sensitivity 0.1 mg and 1 mg.
5.3 Ultrasonic cleaner, with heating function.
5.4 Rotary evaporator.
5.5 Plastic centrifuge tube with stopper. 50 mL.
5.6 Concentrate bottle. 100 mL.
5.7 Vortex mixer.
5.8 Centrifuge, the speed is greater than 5 000 r/min.
5.9 The refrigerated crusher, with a speed greater than 15 000 r/min, is equipped with a grinding cup that can be used for liquid nitrogen cooling.
5.10 Needle water phase filter. 0.45 μm.
6 Measurement procedure
6.1 Sample preparation
Cut the sample into small pieces below 3 mm×3 mm, and then freeze and crush them to particles with a particle size of not more than 1 mm, ready for use.
6.2 Sample processing
Accurately weigh 1 g of the sample (accurate to 1 mg) into a 50 mL plastic centrifuge tube (5.5) with a stopper, add 30 mL of methanol (4.2),
Add 0.5 mL of BHA solution (4.6), ultrasonically extract at 40 ℃ for 60 min, centrifuge at 3 000 r/min for 3 min, take all the supernatant,
Re-extract once, combine the extracts in a concentrating bottle (5.6), and concentrate at 40 ℃ to about 2 mL.
Activate the solid phase extraction column (4.8) with 5 mL of acetonitrile (4.1), discard the eluent; place the activated solid phase extraction column (4.8) in another
On a concentrating bottle (5.6), take the above concentrated solution and apply it to the column, wash the concentrating bottle (5.6) with 3 mL and 2 mL of acetonitrile (4.1) and wash
The purified acetonitrile was applied to the column, and then the solid phase extraction column (4.8) was eluted with 5 mL of acetonitrile (4.1), and all the eluate was collected.
The eluent was concentrated to dryness at 40 ℃, and 2.00 mL of mobile phase (4.7) was accurately added to dissolve the ethylene thiourea in the residue, over 0.45 μm
Filter membrane (5.10), to be analyzed.
6.3 Matrix calibration working curve
Take an appropriate amount of 4.5 medium ethylene thiourea standard stock solution, dilute with acetonitrile to obtain the concentration of 2.0 mg/L, 4.0 mg/L, 10.0 mg/L, 20.0
mg/L, 50.0 mg/L and 100.0 mg/L serial dilution standard solutions, respectively take 1.00 mL each of the above diluted standard solutions and add to 1 g (precise
To 1 mg) blank sample matrix, follow the steps specified in 6.2 to obtain the matrix calibration curve of ethylene thiourea, and the final instrument
The analyzed concentrations of ethylene thiourea were 1.0 mg/kg, 2.0 mg/kg, 5.0 mg/kg, 10.0 mg/kg, 25.0 mg/kg and 50.0 mg/kg.
6.4 Blank experiment
Except that the sample is not weighed, the rest are carried out according to the steps in 6.2.
6.5 Determination
6.5.1 Chromatographic detection conditions
Since the test results depend on the instrument used, it is impossible to give general parameters for HPLC analysis. Set parameters
It should be ensured that the measured component and other components can be effectively separated during chromatographic determination. The following parameters have proved feasible.
a) Chromatographic column. C18 column, 250 mm×4.6 mm, 5 μm, or equivalent;
b) Chromatographic column temperature. 35 ℃;
c) Mobile phase. Acetonitrile. water = 30.70, volume ratio;
d) Flow rate. 1.0 mL/min;
e) Detection wavelength. 234 nm;
f) Injection volume. 10 μL;
g) Running time. 15 min.
6.5.2 High performance liquid chromatography determination
According to the chromatographic detection conditions of the high performance liquid chromatograph set in 6.5.1, after the instrument is stable, the matrix calibration work curve
Make solution (6.3), blank solution (6.4) and sample constant volume solution (6.2) equal volume interspersed sample injection determination. Take the chromatographic peak area as the Y axis,
Taking the concentration as the X axis, draw the standard curve, the matrix calibration working solution and the response value of the ethylene thiourea in the sample to be tested should be
Within the linear range detected by the instrument, the chromatographic peak area is quantified by external standard method.
The typical liquid chromatogram and ultraviolet spectrum of the standard solution are shown in Figure A.1 and Figure A.2.in Appendix A.
7 Calculation and expression of test results
Calculate the residual amount of ethylene thiourea in the sample with a chromatographic data processor or according to formula (1).
8 Recovery rate and precision
...
