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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard has been redrafted and modified in relation to ISO 17234-2:2011 Leather - Chemical Tests for the Determination of Certain Azo Colorants in Dyed Leathers - Part 2: Determination of 4-aminoazobenzene.
This standard has structural adjustment and technical differences with respect to ISO 17234-2:2011. A list of structural changes and technical differences, together with their reasons is given in Annex D for reference.
This standard was proposed by China National Light Industry Council.
This standard is under the jurisdiction of National Technical Committee on Leather Industry of Standardization Administration of China (SAC/TC 252).
Leather and Fur - Chemical Tests - Determination of 4-aminoazobenzene Derived from Azo Colorants
1 Scope
This standard specifies the detection method of gas chromatography-mass spectrometry and high performance liquid chromatography for 4-aminoazobenzene (CAS No.: 60-09-3) derived from some azo colorants and existed in free state.
This standard is applicable to various leathers, furs and their products.
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 6682-2008 Water for Analytical Laboratory Use - Specification and Test Methods (ISO 3696:1987, MOD)
QB/T 1267 Fur - Chemical, Physical and Mechanical and Fastness Tests - Sampling Location
QB/T 1272 Fur - Preparation of Chemical Test Samples
QB/T 2706 Leather - Chemical, Physical and Mechanical and Fastness Tests - Sampling Location (QB/T 2706-2005, ISO 2418:2002, MOD)
QB/T 2716 Leather - Preparation of Chemical Test Samples (QB/T 2716-2005, ISO 4044:1997, MOD)
3 Principle
After degreasing, the specimen is treated with sodium dithionite in an alkaline medium at 40℃ in a closed vessel. 4-aminoazobenzene obtained by reductive cleavage in the process is extracted with tert-butyl methyl ether. The determination of 4-aminoazobenzene is performed using gas chromatography with a mass-selective detector (GC-MS) or high-performance liquid chromatography with a diode array detector (HPLC/DAD).
Since the derivation of amines in very small amounts may lead to false positive results, Annex XVII of the Regulation REACH 1907/2006 defines a limit amine value of 30mg/kg in leather specimen. This value only applies to analytical specimen that is homogenous in matrix, but not to a mixed sample of heterogeneous composition.
If the detected amount of 4-aminoazobenzene is over 30mg/kg, it must be assumed that a certain azo colorant was used. Below 30mg/kg, it is at present not possible to make a reliable statement on the use of certain azo colorants without further information such as the type and/or purity of the colorants used or the other raw materials used.
Note: The detection and determination of 4-aminoazobenzene is performed using high-performance liquid chromatography with a diode array detector (HPLC/DAD) or mass selective detector (HPLC/MS), capillary gas chromatography with a mass-selective detector (GC/MS) or capillary electrophoresis with a diode array detector (CE/DAD), or qualitatively with thin-layer chromatography (TLC, HPTLC). Other chromatographic methods are detailed in Annex C.
If 4-aminoazobenzene is detected by one chromatographic method, confirmation shall be made using one or more alternative methods. Amine quantification is performed by HPLC/DAD.
4 Reagents
Unless otherwise specified, only confirmed analytical reagent and Grade 3 water specified in GB/T 6682-2008 are used.
4.1 n-hexane.
4.2 Sodium hydroxide solution, 20g/L.
4.3 Sodium dithionite solution, 200mg/mL. Weigh sodium dithionite (Na2S2O4 content≥85%), dissolve it with right amount of water, then place it in closed vessel. It is prepared immediately before use.
4.4 tert-butyl methyl ether, chromatographically pure.
Note: If there is no tert-butyl methyl ether, fresh ethyl ether may be used as a substitute. Fresh ethyl ether is prepared as follows: put 500mL of ethyl ether into a 1,000mL separating funnel, add 100mL of 5% ferrous sulfate solution, fiercely shake out, discard the water layer and place the solution in an all-glass device for distillation, then collect 33.5℃~34.5℃ fraction.
4.5 Sodium chloride.
4.6 Methanol, chromatographically pure.
4.7 Acetonitrile, chromatographically pure.
4.8 4-aminoazobenzene, standard, purity≥98%, CAS No.: 60-09-3.
4.9 Ammonium dihydrogen phosphate.
4.10 Disodium hydrogen phosphate.
4.11 Anthracene-d10,internal standard, used for GC-MS analysis, purity ≥98%, CAS No.: 1719-06-8.
4.12 Standard solutions.
4.12.1 Anthracene-d10 standard solution, 2.0μg/mL, internal standard solution, prepared by tert-butyl methyl ether (4.4).
Note: Solution of other appropriate concentrations can be prepared according to the need.
4.12.2 4-aminoazobenzene standard stock solution, 500mg/L, prepared by tert-butyl methyl ether (4.4) or other appropriate solvent.
Note: The solution is stored in brown bottle, and a small amount of anhydrous sodium sulfate can be added; then the solution is preserved at below -18℃ for one month.
4.12.3 4-aminoazobenzene standard working solution, 30mg/L, prepared by tert-butyl methyl ether (4.4) or other appropriate solvent.
Note: Solution of other appropriate concentrations can be prepared according to the need.
5 Apparatus
5.1 Analytical balance, with division value of 0.1mg.
5.2 Glass reactor, which is tubular, high temperature resistant and sealable.
5.3 Ultrasonic bath, at least 160W, with temperature regulating device.
5.4 Thermostatic waterbath or appropriate heater, with accuracy of ±2℃.
5.5 Polypropylene or polyethylene syringe, 2mL.
5.6 Mechanical oscillator, with rotation speed≥300r/min.
5.7 Centrifuge, with rotation speed≥300r/min.
5.8 Rotary vacuum evaporator.
5.9 Gas chromatography - mass-selective detector (GC-MS), with electron impact (EI).
5.10 High-performance liquid chromatography (HPLC), with diode array detector (DAD).
6 Specimen Preparation
6.1 Sampling
6.1.1 Sampling at standard position
Sample according to QB/T 2706 for leather and according to QB/T 1267 for fur.
6.1.2 Sampling at non-standard location
Where sampling at standard positions (e.g. sampling directly from shoes and clothes) is impracticable, the sampling shall be carried out at any position within the available area. The sample shall be representative and detailed record about sampling shall be given in the test report.
In the case of fabrics with various patterns and colors on leather sample, sample of each material and each color shall be taken and tested respectively as possible.
6.2 Specimen preparation
Leather specimen is prepared according to QB/T 2716 and fur specimen is prepared according to QB/T 1272. Feather loss shall be avoided during sampling process.
Any traces of adhesives and attachments shall be removed from sample as possible.
Foreword i
1 Scope
2 Normative References
3 Principle
4 Reagents
5 Apparatus
6 Specimen Preparation
7 Analysis Procedure
8 Result Calculation
9 Detection Limit and Recovery Rate
10 Result Expression
11 Test Report
Annex A (Informative) HPLC-DAD Chromatogram and Spectrogram
Annex B (Informative) GC-MS Chromatogram and Mass Spectrum
Annex C (Informative) Other Chromatographic Methods
Annex D (Informative) Technical Differences Together with Their Reasons Between this Standard and ISO 17234-2:
