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SN/T 5257-2019Determination of isooctyl thioglycolate di-n-octyltin in plastics and their products Gas chromatography-mass spectrometry (English PDF)

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Issued by

General Administration of Customs

Level / Type

National · Recommended

Issue date

January 1, 1970

Implementation date

July 1, 2020

Scope

SN/T 5257-2019 (Determination of isooctyl thioglycolate di-n-octyltin in plastics and their products Gas chromatography-mass spectrometry) is available as an English-translated PDF.

SN/T 5257-2019 — This standard specifies the gas chromatography-mass spectrometry determination of iso-octyl thioglycolate di-n-octyltin content in plastics and its products method.

This standard is only applicable to plastics and their products that are soluble in tetrahydrofuran and contain only isooctyl thioglycolate di-n-octyl tin. Determination of isooctyl glycolate di-n-octyl tin.

The lower limit of determination of 2-n-octyl tin thioglycolate isooctyl ester in this standard is 2.0 mg/kg.

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Document preview — SN/T 5257-2019

National Standard of the People's Republic of China

ICS: 83.140.30
Classification: G 31

Issued by: General Administration of Customs

Foreword
1 Scope
2 Normative references
3 Method summary
4 Reagents and materials
5 Apparatus and equipment
6 Analysis steps
6.1 Sample extraction
6.2 Derivatization reaction
6.3 Preparation of standard working curve
6.4 Determination
7 Result calculation
8 Precision

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 organization of this standard. Ningbo Customs of the People's Republic of China.

1 Scope

This standard specifies the gas chromatography-mass spectrometry determination of iso-octyl thioglycolate di-n-octyltin content in plastics and its products method.

This standard is only applicable to plastics and their products that are soluble in tetrahydrofuran and contain only isooctyl thioglycolate di-n-octyl tin.

Determination of isooctyl glycolate di-n-octyl tin.

The lower limit of determination of 2-n-octyl tin thioglycolate isooctyl ester 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 GB/T 6379.2 Measurement method and accuracy of results

3 Method summary

After the sample is dissolved in tetrahydrofuran solvent, a certain amount of methanol is added for precipitation, centrifuged, washed, combined with the clear liquid, and rotated After evaporating to a constant volume, take the extract, adjust the pH value (pH value = 4.0 ± 0.1), add sodium tetraethyl boride solution for derivatization reaction, use the reactants were extracted with n-hexane, determined by gas chromatography-mass spectrometry, and quantified by external standard method. The by-products of the reaction were extracted with ethyl acetate.

Use gas chromatography-mass spectrometer for qualitative analysis.

4 Reagents and materials

Unless otherwise specified, the reagents used in this standard are of analytical grade, and the experimental water should meet the requirements of secondary water specified in GB/T 6682.

4.1 Tetrahydrofuran.

4.2 Methanol.

4.3 Sodium acetate.

4.4 Glacial acetic acid.

4.5 n-hexane.

4.6 Ethyl acetate.

4.7 Sodium tetraethyl boride. purity >= 98.0%.

4.8 Isooctyl thioglycolate (CAS number. 7659-86-1). purity >= 95.0%.

4.9 Isooctyl thioglycolate di-n-octyl tin (DOTE, CAS number. 15571-58-1). purity >= 99.0%.

4.10 Sodium acetate/glacial acetic acid buffer solution. Dissolve 84g sodium acetate (4.3) into 1 L of water, then adjust with glacial acetic acid (4.4) pH value = 4.0±0.1.

4.11 Derivatization solution. quickly weigh 0.2 g sodium tetraethyl boride (4.7) into a glass test tube (5.8) with a stopper, and dilute to volume with water 10 mL.

4.12 Qualitative standard solution. Weigh 0.1 g (accurate to 0.1 mg) of isooctyl thioglycolate (4.8), and dissolve the dilute with ethyl acetate (4.6) Release to 10 mg/L, store at 4 °C.

4.13 Standard stock solution (1 000 µg/mL). Weigh 0.1 g (accurate to 0.1 mg) isooctyl thioglycolate di-n-octyl tin (4.9), Dilute to 100 mL with methanol (4.2) and store at 4°C.

4.14 Standard working solution. Dilute the standard stock solution (4.13) with methanol (4.2) to obtain a concentration of 10 µg/mL, 20 µg/mL, Standard working solution series of 50 µg/mL, 100 µg/mL and.200 µg/mL.

5 Apparatus and equipment

5.1 Gas chromatography-mass spectrometer. with EI source.

5.2 Balance. Sensitivity 0.1 mg.

5.3 Ultrasonic extractor, power. 3 000 W.

5.4 pH meter. accuracy ±0.02 pH value.

5.5 Centrifuge. speed > 5 000 r/min.

5.6 Rotary evaporator.

5.7 Vortex mixer, rotating speed > 3 000 r/min.

5.8 Glass test tube with stopper. 10 mL.

5.9 Organic membrane filter head. 0.45 µm.

6 Analysis steps

6.1 Sample extraction

Cut the sample into small pieces of 1 mm×1 mm, weigh 0.5 g (accurate to 0.1 mg) with a balance into a conical flask, and add 10 mL of tetrahydrogen Furan (4.1) solution was extracted with an ultrasonic extractor (5.3) for 30 min until it was completely dissolved, and 20 mL of methanol (4.2) was added for precipitation.

After centrifugation, the supernatant was removed, 2 mL methanol (4.2) was added in 3 times to wash the precipitate, and the washing liquid was combined in a 100 mL pear-shaped flask, and Evaporate on the evaporator (5.6) to near dryness, add 1 mL of methanol (4.2) to dissolve the residue, add 0.5 mL of methanol (4.2) in 2 times to wash in a pear-shaped bottle, combine methanol in a 10 mL stoppered glass test tube (5.8) for the derivatization reaction.

6.2 Derivatization reaction

Add 5 mL of sodium acetate/glacial acetic acid buffer solution (4.10) to the extract, add 2 mL of derivatization solution (4.11), and ultrasonically react 15 min, add 2 mL n-hexane (4.5), mix with a vortex mixer at 3 000 r/min for 60 s, then ultrasonically extract for 10 min, take the upper layer of n-hexane, after passing through an organic filter membrane, is used for qualitative analysis by gas chromatography-mass spectrometry.

Add 2 mL of ethyl acetate (4.6) to the lower aqueous solution, mix well with a vortex mixer, and take the upper ethyl acetate after the layers are separated the test solution is passed through an organic filter membrane for qualitative analysis by gas chromatography-mass spectrometry.

6.3 Preparation of standard working curve

Accurately draw 2 mL of the standard working solution (4.14), place it in a 10 mL stoppered glass test tube (5.8), and carry out the extraction according to 6.2.

Biochemical reaction. The resulting solution was determined according to the conditions of 6.4.1 and used for qualitative analysis by gas chromatography-mass spectrometry.

6.4 Determination

6.4.1 Gas Chromatography-Mass Spectrometry Conditions

Since the test results depend on the instrument used, it is impossible to give general parameters for gas chromatography-mass spectrometry analysis. set up the parameters of should ensure that the measured component and other components can be effectively separated during chromatographic determination. The following parameters have been proved to be feasible.

a) Chromatographic column. capillary column, DB-5MS, 30 m×250 µm×0.10 µm;

b) Column temperature. the initial temperature is 60 °C, the temperature is increased to 220 °C at 20 °C/min, and kept for 4 min, and the temperature is increased to 280 °C at 20 °C/min.

Hold for 5 min;

c) Temperature of the injection port. 280 °C;

d) Chromatography-mass spectrometry interface temperature. 280 °C;

e) Ion source temperature. 230 °C;

f) MS quadrupole temperature. 150 °C;

g) Solvent delay. 4 min;

h) Carrier gas. high purity helium, flow rate 1.0 mL/min;

i) Ionization method. EI;

j) Measurement method. selective ion detection method, see Table A.1 in Appendix A;

k) Injection volume. 1.0 µL, splitless injection.

6.4.2 Qualitative determination

Determine the test solution and standard working solution according to the conditions of gas chromatography/mass spectrometry. If the chromatographic peaks in the test solution of 6.2 and 6.3 are retained the time is the same as that of the standard working solution, and after subtracting the background, all the characteristic ions appear, and the relative abundance and concentration of the characteristic ions the relative abundance of the equivalent standard working solution is consistent, and the relative abundance deviation does not exceed the regulations in Table 1, then it can be judged that there is a target in the test solution.

6.4.3 Quantitative determination

Under the best working conditions of the instrument, a calibration curve is established based on the relationship between the peak area and the concentration, and the external standard method is used for quantification. standard the response value of the analyte in the working solution and the sample solution should be within the linear response range of the instrument. If the content exceeds the range of the standard curve, the correct After diluting with hexane (4.5) to an appropriate concentration, the characteristic ions and retention time of isooctyl thioglycolate di-n-octyltin are shown in Table A.1.

The extracted ion current chromatogram is shown in Figure A.1, and the full scan mass spectrum of isooctyl thioglycolate di-n-octyltin is shown in Figure A.2.

6.4.4 Blank test

Carry out a blank test with the sample.

7 Result calculation

The content of iso-octyl thioglycolate di-n-octyltin in the sample is calculated according to formula (1).

X - The content of 2-n-octyl tin thioglycolate iso-octyl thioglycolate in the sample in milligrams per kilogram (mg/kg);

c - The concentration of isooctyl thioglycolate di-n-octyltin in the sample solution, in micrograms per milliliter (µg/mL);

c0--The concentration of isooctyl thioglycolate di-n-octyltin in the blank solution, in micrograms per milliliter (µg/mL);

V-the constant volume of the sample, the unit is milliliters (mL);

f --dilution factor;

m--The mass of the sample, in grams (g).

The result is kept to one decimal place.

8 Precision

Six laboratories conduct method precision tests on samples with three levels of concentration, and perform statistics in accordance with GB/T 6379.2.The results are shown in

Table 1.

Appendix A

(Informative appendix) Typical chromatographic data A.1 Isooctyl thioglycolate di-n-octyl tin A.2 Isooctyl thioglycolate

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 7 pages — is available in the English PDF.

Referenced standards

Normative references

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