GB/T 24166-2021Determination of the content of chlorinated phenols in dye products (English PDF)

1 Scope

This document specifies the method for the determination of 19 chlorinated phenols residues in dye products using gas chromatography-mass spectrometry (GC/MS).

This document is applicable to the determination of chlorinated phenols in various categories of dye products.

NOTE: see Appendix A for the types of chlorinated phenols and reference parameters for determination.

1.0 mL of the tetrachloroguaiacol (TCG) internal standard stock solution (see 7.3) into a 10 mL volumetric flask, use methanol to dilute it to the scale, and prepare it into an internal standard working solution of 10 mg/L tetrachloroguaiacol (TCG).

2 Normative References

The contents of the following documents constitute indispensable clauses of this document through the normative references in the text. In terms of references with a specified date, only versions with a specified date are applicable to this document. In terms of references without a specified date, the latest version (including all the modifications) is applicable to this document.

GB/T 6682-2008 Water for Analytical Laboratory Use - Specification and Test Methods

GB/T 8170-2008 Rules of Rounding off for Numerical Values & Expression and Judgement of Limiting Values

3 Terms and Definitions

This document does not have terms or definitions that need to be defined.

4 Method Principle

In an ultrasonic bath, use potassium carbonate solution to extract the chlorinated phenols in the specimen, which is acetylated with acetic anhydride to generate chlorinated phenols acetate.

Though liquid-liquid extraction, extract the chlorinated phenols acetate into n-hexane, then, adopt the gas chromatograph-mass spectrometer (GC/MS) for analysis and qualitative determination. Adopt the peak area internal standard method for quantitative determination.

5 Reagents or Materials

5.1 Unless otherwise specified, only reagents confirmed to be analytically pure and Grade-3 water specified in GB/T 6682-2008 are used.

5.2 The types of chlorinated phenols in the standard substance and the determination parameters shall comply with the stipulations of Appendix A.

5.3 n-Hexane, chromatographically pure.

5.4 Methanol, chromatographically pure.

5.5 Anhydrous potassium carbonate.

5.6 Acetic anhydride.

5.7 Triethylamine.

5.8 Anhydrous sodium sulfate: at 650 °C, dry it for 4 hours, take out and place in a desiccator for later use.

5.9 Potassium carbonate solution: 0.1 mol/L aqueous solution, weigh-take 13.8 g of anhydrous potassium carbonate, dissolve it in water, and reach a constant volume of 1,000 mL.

6 Instruments and Equipment

6.1 Gas chromatograph-mass spectrometer (GC/MS): equipped with EI source.

6.2 Chromatographic column: 50% phenyl methyl polysiloxane stationary phase, for example, DB-17MS, 30 m x 0.25 mm x 0.25 µm or equivalent.

6.3 Analytical balance: with an accuracy of 0.01 mg.

6.4 Ultrasonic generator.

6.5 Extractor: tube with a stopper, 10 mL.

6.6 Centrifuge: 4,000 r/min.

6.7 Separating funnel: 150 mL.

6.8 Separating funnel oscillator: with an oscillation frequency above 200 times/min.

7 Preparation of Standard Solutions

8 Preparation of Sample Solution

11 Result Calculation

The content of various chlorinated phenols in the specimen, expressed in wi, is calculated in accordance with Formula (1):

Where, wi---the content of the target substance in the specimen, expressed in (mg/kg); ri---the ratio of peak area response values of chlorinated phenols in the sample solution and the internal standard substance; ms---the mass value of the standard sample in the mixed standard solution, expressed in (µg); rs---the ratio of peak area response values of chlorinated phenols in the mixed standard solution and the internal standard substance; m---the mass of the specimen, expressed in (g). The calculation results shall retain two decimal places.

The calculation results shall be rounded-off in accordance with the stipulations of GB/T 8170- 2008.

12 Detection Limit, Precision and Accuracy