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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 24101-2009 Limit and determination of 4-aminoazobenzene in dye products. In addition to editorial changes, the following main technical changes have been made with respect to GB/T 24101-2009:
——High-performance liquid chromatography for the determination of 4-aminoazobenzene is added (see 4.2).
This standard was proposed by China Petroleum and Chemical Industry Association.
This standard is under the jurisdiction of Technical Committee on Dyestuff of Standardization Administration of China (SAC/TC 134).
The previous edition of this standard is as follows:
——GB/T 24101-2009.
Limit and determination of 4-aminoazobenzene in dye products
Warning: The personnel using this standard shall have practical experience in laboratory work. This standard does not address all of the safety problems. The users are under the obligation to adopt proper safety and health measures and shall ensure conformance with the requirements specified in national relevant regulations.
1 Scope
This standard specifies the limit requirements and determination methods for 4-aminoazobenzene (see Annex A) in dye products.
It applies to the limit and determination of 4-aminoazobenzene in commercial dyes, dye products, dye intermediates and textile dyeing auxiliaries.
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)
GB/T 8170-2008 Rules of rounding off for numerical values & expression and judgment of limiting values
3 Requirements
The content of 4-aminoazobenzene (see Annex A) in dye products shall be less than or equal to 150mg/kg, in which the limit of 4-aminoazobenzene in liquid dye and pigment printing paste shall be converted according to its solid content.
4 Test methods
4.1 Gas chromatography-mass spectrometry (arbitration method)
4.1.1 Principle
The dye sample is subjected to reductive pyrolysis with sodium hydrosulfite in weakly alkaline medium, and the azo bond of 4-aminoazobenzene is kept non-breaking by controlling the pyrolysis temperature and the pyrolysis time; 4-aminoazobenzene in the pyrolysis solution is extracted with a solvent; after concentration, it is tested by gas chromatograph-mass spectrometer and quantified by characteristic ion external standard method.
4.1.2 Determination methods
4.1.2.1 General
Unless otherwise specified, only recognized analytical reagent and Grade 3 water (specified in GB/T 6682-2008) shall be used in analysis. Judgment of the inspection result shall be carried out according to the rounding-off value comparison method specified in GB/T 8170-2008, 4.3.3.
4.1.2.2 Reagents and solutions
4.1.2.2.1 Sodium chloride
4.1.2.2.2 Sodium hydroxide solution: 20g/L.
4.1.2.2.3 Acetone.
4.1.2.2.4 Sodium hydrosulfite (rongalite).
4.1.2.2.5 Anhydrous sodium sulfite.
4.1.2.2.6 Anhydrous sodium sulfate.
4.1.2.2.7 Anhydrous ether: it shall be purified when being used as it is easy to produce peroxide after long time storage. Take 500mL of ether, add 100mL of ferrous sulfate solution (50g/L aqueous solution), shake well and then discard the water layer, re-distill it in an all-glass device, and collect fractions of 33.5°C to 34.5°C.
4.1.2.2.8 Ethyl acetate.
4.1.2.2.9 Methanol: chromatographically pure.
4.1.2.2.10 4-aminoazobenzene standard: content (mass fraction) ≥ 98%.
4.1.2.2.11 Standard stock solution: weigh proper amount of 4-aminoazobenzene standard, dissolve it with methanol and prepare into standard stock solution of about 1.0mg/mL. Properly seal the standard stock solution and store it in a refrigerator at 0℃~4℃. It is valid for 6 months.
4.1.2.2.12 Standard working solution: dilute the standard stock solution with methanol and prepare it into the standard working solution of proper concentration. Properly seal the standard working solution and store it in a refrigerator at 0℃~4℃. It is valid for 1 month.
4.1.2.3 Apparatuses
4.1.2.3.1 Gas chromatograph-mass spectrometer (GC-MS).
4.1.2.3.2 Chromatographic column: capillary column with 50% of phenyl-methylpolysilicone stationary phase, 30m×0.25mm×0.25μm or the equivalent.
4.1.2.3.3 Microinjector or automatic sample injector: 10μL.
4.1.2.3.4 Extractor: made of hard glass, tubular, with ground mouth and bottle stopper,50mL.
4.1.2.3.5 Ground centrifugal tube with stopper: 10mL or 25mL.
4.1.2.3.6 Centrifuge: 4 000r/min.
4.1.2.4 Sample pretreatment
Accurately weigh 0.1g of sample (1mL of liquid sample) to the nearest 0.000 1g, add 7g of sodium chloride to the extractor, then add 9mL of sodium hydroxide solution and make them fully infiltrate and dissolve (if the sample is difficult to be dissolved, add 5mL of acetone), shake well and add 0.2g of rongalite to fully oscillate and dissolve. Put it into 40±2℃ water bath for thermal insulation for 30min, shake the extractor intermittently to make the sample pyrolyzed, then take it out and cool to room temperature. Extract for three times with anhydrous ether, 10mL per time, (if it is difficult to layer and separate during extraction, transfer the solution to a ground centrifugal tube with stopper for centrifugation), collect the extract into a 50mL beaker, add about 0.5mL of ethyl acetate, and about 0.5g of anhydrous sodium sulfite (antioxidant) and anhydrous sodium sulfate (desiccant) to heat under infrared light so as to make the ether solution gently and evenly boiling. When the remaining solution is slightly less than 1mL, transfer it into a graduated small sample bottle, make up to 1.0mL with ethyl acetate. Determine the recovery rate after the standard samples is treated under the same conditions.
4.1.2.5 Gas chromatography-mass spectrometry analysis conditions
As the test result depends on the used apparatus, it is impossible to give general parameters for the chromatographic analysis. The following parameters (see Table 1) have been proved appropriate to the test.
Table 1 Gas chromatography-mass spectrometry analysis conditions
Control parameter Operation condition
Carrier gas Helium (99.999%)
Carrier gas flow/(mL/min) 1.0
Injection port temperature/℃ 300
Ion source temperature/℃ 230
Transfer line temperature/℃ 280
Injection mode Splitless injection
Ionization method EI
Injection volume/μL 1.0
Column temperature programming Keep at an initial temperature of 80℃ for 2min; rise to 150℃ at 5℃/min, keep for 0min and then rise to 260℃ at 8℃/min, keep for 0min, finally rise to 280℃ at 30℃/min and keep for 10min.
4.1.2.6 Determination
According to the content of the substance to be tested in the specimen, select standard working solution with similar concentration for the determination. Respectively take specimen solution and standard working solution for determination according to the above chromatographic analysis conditions, and quantify by an external standard method. See Figure B.1 in Annex B for gas chromatography-mass spectrometry total ion chromatogram of 4-aminoazobenzene standard sample.
4.1.2.7 Result calculation
The 4-aminoazobenzene content which is represented by mass fraction ω1 and expressed in mg/kg is calculated according to equation (1):
(1)
where,
A——the peak area of 4-aminoazobenzene target ion in specimen solution;
c——the corresponding concentration of 4-aminoazobenzene in standard solution, μg/mL;
V——the final constant volume of specimen solution, mL;
A8——the peak area of 4-aminoazobenzene in standard solution;
m——the mass of specimen, g.
Round the calculation result to one decimal place.
4.1.2.8 Permissible deviation
The absolute value of the difference between the two parallel determination results of 4-aminoazobenzene content shall be no more than 20% of the arithmetic mean, and the arithmetic mean thereof is taken as the determination result.
4.1.2.9 Lower determination limit
The lower limit of gas chromatography-mass spectrometry in this standard is 1.0mg/kg.
4.1.2.10 Recovery rate
Adopt standard addition technique; add 1.0mL of standard working solution to 0.1g of the dye product which is free of 4-aminoazobenzene as determined by this method, operate according to the gas chromatography-mass spectrometry given in 4.1, and the measured recovery rate of various 4-aminoazobenzenes shall be between 80% and 120%.
4.1.2.11 Precision
The absolute difference between the results of two mutually independent tests performed by the same operator for the same object, with the same equipment and test method and in the same laboratory during a short time shall not be greater than 20% the arithmetic mean.
4.2 High-performance liquid chromatography
4.2.1 Principle
The dye sample is subjected to reductive pyrolysis with sodium hydrosulfite in weakly alkaline medium, and the azo bond of 4-aminoazobenzene is kept non-breaking by controlling the pyrolysis temperature and the pyrolysis time; 4-aminoazobenzene in the specimen is extracted with anhydrous ether; the extract is determined by high-performance liquid chromatography-ultraviolet detector and quantified by external standard method.
4.2.2 Determination method
4.2.2.1 General
Unless otherwise specified, only recognized analytical reagent and Grade 3 water (specified in GB/T 6682-2008) shall be used in analysis. Judgment of the inspection result shall be carried out according to the rounding-off value comparison method specified in GB/T 8170-2008, 4.3.3.
4.2.2.2 Apparatuses
4.2.2.2.1 Liquid chromatograph: infusion pump - with flow range from 0.1mL/min to 5.0mL/min, flow stability of ±1% in this range; detector - PDA detector or UV spectroscopic detector with variable wavelength or those with equivalent performance.
4.2.2.2.2 Chromatographic column: a stainless steel column with length of 150mm and inner diameter of 4.6mm, stationary phase of C18 and particle size of 5μm.
4.2.2.2.3 Chromatographic working station.
4.2.2.2.4 Supersonic generator.
4.2.2.2.5 Microinjector or automatic sample injector.
4.2.2.2.6 Extractor: made of hard glass, tubular, with ground mouth and bottle stopper, 50mL.
4.2.2.2.7 Microfiltration membrane (aqueous phase): with hole diameter of 0.45μm.
4.2.2.2.8 Syringe filter: with hole diameter of 0.45μm.
4.2.2.3 Reagents and solutions
4.2.2.3.1 Acetonitrile: chromatographically pure.
4.2.2.3.2 4-aminoazobenzene standard: content (mass fraction) ≥ 98%.
4.2.2.3.3 Sodium chloride.
4.2.2.3.4 Sodium hydrosulfite (rongalite).
4.2.2.3.5 Sodium hydroxide solution: 20g/L.
4.2.2.3.6 Anhydrous ether: the same as that in 4.1.2.2.7.
4.2.2.3.7 Water: filtered through a microporous membrane (aqueous phase).
4.2.2.4 Chromatographic analysis conditions
4.2.2.4.1 Mobile phase: Phase A is acetonitrile; Phase B is water. See Table 2 for mobile phase gradient procedure.
Table 2 Mobile phase gradient procedure
Time/min 0 3 30 35 40 50
Phase A (Volume fraction)/% 10 10 90 90 10 10
Phase B (Volume fraction)/% 90 90 10 10 90 90
4.2.2.4.2 Detection wavelength: 380nm.
4.2.2.4.3 Flow: 1.0mL/min.
4.2.2.4.4 Column temperature: 40℃.
4.2.2.4.5 Injection volume: 20μL.
4.2.2.5 Solution preparation
4.2.2.5.1 Preparation of standard solution
The same as those in 4.1.2.2.11 and 4.1.2.2.12.
4.2.2.5.2 Preparation of specimen solution
Accurately weigh 0.1g of specimen (1mL of liquid sample), put it in an extractor, to the nearest 0.1mg, add 9mL of sodium hydroxide solution to the extractor, shake to make the dye evenly dispersed, add 7g of sodium chloride, and make them fully infiltrate and dissolve. Shake well and add 0.2g of rongalite to fully oscillate and dissolve. Put it into 40±2℃ water bath for thermal insulation for 30min, shake the test tube intermittently to make the sample pyrolyzed, then take it out and cool to room temperature. Accurately add 10.0mL of anhydrous ether, cover the stopper tightly, shake vigorously (manual shaking about 100 times) and keep it still. After the two phases are separated, take the supernatant and filter with a syringe filter for HPLC analysis.
4.2.2.6 Determination
The optimal analysis conditions can be selected according to apparatuses, and the mobile phase shall be shaken up and then degassed by a supersonic generator. After the apparatus is stable, determine the standard solution and the specimen solution according to the chromatographic analysis conditions in 4.2.2.4. Qualify as per retention time and quantify as per chromatographic peak area by external standard method. The detection range of 4-aminoazobenzene applicable to this standard is 5mg/kg to 1 000mg/kg. If the content of 4-aminoazobenzene in the specimen exceeds the detection range, the sample volume of the test solution can be reduced and the dilution ratio can be adjusted for analysis. After the last constituent flows out, the result is processed. See Figure B.2 for liquid chromatogram of 4-aminoazobenzene standard sample.
Foreword i
1 Scope
2 Normative references
3 Requirements
4 Test methods
5 Test report
Annex A (Normative) Structure information of 4-aminoazobenzene
Annex B (Informative) Standard chromatogram of 4-aminoazobenzene
