GB/T 43821-2024Textiles - Determination of lead release (English PDF)

0 Warning

A warning on the first page of the body states that the persons using this document are to have practical experience of regular laboratory work, that the document does not point out all the possible safety problems, and that it is the responsibility of the user to take suitable safety and health measures and to ensure compliance with the conditions laid down by the relevant national laws and regulations.

1 Scope

This document describes test methods for determining the lead released by textiles and by the accessories of textile products after treatment with artificial saliva, using an inductively coupled plasma optical emission spectrometer (ICP-OES), a graphite furnace atomic absorption spectrometer (GFAAS) or an inductively coupled plasma mass spectrometer (ICP-MS).

It applies to the testing of textiles and of the accessories of textile products, such as buttons and zips.

2 Normative references

The contents of the following documents constitute indispensable provisions of this document through normative reference in the text. For dated references, only the edition corresponding to that date applies; for undated references, the latest edition, including all amendments, applies.

The list comprises GB/T 6682 Water for analytical laboratory use - Specification and test methods; GB/T 18886-2019 Textiles - Tests for colour fastness - Colour fastness to saliva; GB/T 30156 Method for corrosion and abrasion of coated accessories of textile products; GB/T 30158-2013 Determination of nickel release from accessories of textile products; and GB/T 40139 Measurement of material surface area - Hyperspectral imaging three-dimensional area measurement method.

3 Terms and definitions

This document has no terms and definitions that need to be defined.

4 Principle

After preparation the specimen is placed in artificial saliva and shaken; the lead concentration in the artificial saliva after shaking is determined with an inductively coupled plasma optical emission spectrometer, a graphite furnace atomic absorption spectrometer or an inductively coupled plasma mass spectrometer, and the lead release of the specimen per unit of time is calculated together with the tested surface area of the specimen. The lead release is expressed in micrograms per square centimetre per hour.

5 Reagents or materials

Unless otherwise specified, all reagents are of guaranteed grade and the water is grade one water as specified in GB/T 6682.

Nitric acid: 65 % by mass fraction, density 1.40 g/mL.

Lead standard stock solution at 1 000 µg/mL: 0.160 g of lead nitrate is weighed on the electronic balance, dissolved with 10 mL of 10 % nitric acid solution by volume, transferred to a 100 mL volumetric flask and diluted to the mark with 10 % nitric acid solution by volume, giving a stock solution of 1 000 µg/mL; when turbidity, precipitate or a change of colour appears during storage, the stock solution is prepared afresh. Lead standard substances or standard sample stock solutions certified and issued with a reference material certificate by the State may also be used. A note records that the lead standard stock solution keeps for 6 months at ordinary temperature, 15 °C to 25 °C.

Lead standard intermediate working solution at 10 µg/mL: 1 mL of the lead standard stock solution is accurately transferred to a 100 mL volumetric flask and diluted to the mark with 1 % nitric acid solution by volume; when turbidity, precipitate or a change of colour appears during storage, it is prepared afresh. A note records that the intermediate working solution keeps for 2 weeks at ordinary temperature, 15 °C to 25 °C.

Lead series standard working solutions: a measured quantity of the intermediate working solution is accurately transferred to a 100 mL volumetric flask and diluted to the mark with 1 % nitric acid solution by volume to give a series of suitable concentration. For determination with an inductively coupled plasma optical emission spectrometer the series may be made up at 0.00 µg/mL, 0.02 µg/mL, 0.04 µg/mL, 0.20 µg/mL, 0.40 µg/mL, 0.80 µg/mL and 1.00 µg/mL; for determination with a graphite furnace atomic absorption spectrometer or an inductively coupled plasma mass spectrometer the series may be made up at 0.00 µg/mL, 0.01 µg/mL, 0.02 µg/mL, 0.04 µg/mL, 0.05 µg/mL, 0.08 µg/mL and 0.10 µg/mL. The lead series standard working solutions are used as soon as they are prepared.

Bismuth internal standard stock solution at 1 000 µg/mL or 100 µg/mL: a bismuth standard substance or standard sample stock solution certified and issued with a reference material certificate by the State. A note records that it keeps for 12 months at ordinary temperature, 15 °C to 25 °C. Bismuth internal standard working solution: a measured quantity of the stock solution is accurately transferred and diluted stepwise with 1 % nitric acid solution by volume to a suitable concentration, for instance 0.005 µg/mL, and is used as soon as it is prepared.

Artificial saliva: prepared according to 4.3 of GB/T 18886-2019, kept away from light, valid for 1 week. Degreasing solution: a suitably diluted neutral detergent, for instance an aqueous solution of sodium dodecylbenzene sulfonate at a mass fraction of 0.5 %. Wax or lacquer: free of lead, used to coat the non-tested surfaces of the specimen so as to prevent lead being released from those surfaces during the test.

6 Apparatus

An inductively coupled plasma optical emission spectrometer, a graphite furnace atomic absorption spectrometer or an inductively coupled plasma mass spectrometer.

A constant temperature water bath shaker, with the temperature controlled at (37 +/- 2) °C and a shaking frequency of (60 +/- 5) r/min.

An electronic balance with a scale division of 0.001 g; a steel rule with a measuring range of 0 mm to 200 mm and a scale division of 1 mm; covered containers fitted with screw seal caps and made of non-metallic, lead-free and nitric acid resistant materials, such as glass, polypropylene, polytetrafluoroethylene and polystyrene, which before use are soaked for at least 4 h in 5 % nitric acid solution by volume; and volumetric flasks of 50 mL, 100 mL and other sizes.

7.1 Preparation of the test specimens

Textiles - sampling: the textile specimen is cut to (10.0 +/- 0.5) cm2 or to another suitable size. As far as possible three specimens of the same batch are taken for the test. A note records that fabrics are mainly flexible materials and that, on the reasonable assumption that any part of the fabric can be sucked or put into the mouth by infants and children, the size of the fabric is not restricted.

Textiles - measurement of the tested area: the tested area of the textile specimen is measured accurately and calculated with the steel rule.

Textile accessories - sampling: the parts of the accessories of textile products that can be put into the mouth by infants and children are sampled and tested. In order to reach the analytical sensitivity of the instrument and the minimum sample intake, the tested area of the specimen is at least 0.5 cm2; where necessary, identical specimens may be tested together to reach that minimum area. As far as possible three specimens of the same batch are taken for the test. A note records that an accessory is considered able to be put into the mouth by infants and children when any one dimension of the accessory, height, length or width, is less than 5 cm, or when any one dimension of a detachable or protruding part that could reasonably be assumed to come into contact with infants and children is less than 5 cm.

Textile accessories - measurement of the tested area: the tested area of the accessory is measured according to A.1 in Annex A of GB/T 30158-2013 or according to GB/T 40139.

Abrasion simulation: for coated accessories of textile products, that is electroplated, painted, polymer or similar coatings, reference is made to FZ/T 01163 to identify whether the coating of the textile accessory contains lead. Accessories with lead-free coatings are corroded and abraded according to GB/T 30156 and, where possible, the whole item is treated; accessories with lead-containing coatings are not subjected to the corrosion and abrasion treatment.

Masking: where the specimen has non-tested surfaces, that is faces that cannot be put into the mouth of infants and children, those surfaces are removed or protected so that they do not come into contact with the artificial saliva, in order to avoid lead being released from them; one or more layers of the lead-free wax or lacquer are applied to the non-tested surfaces.

Degreasing: at room temperature the prepared textile accessory is placed in the degreasing solution and stirred gently for 2 min, rinsed with water and dried in air. The degreasing step applies only to the parts of the specimen from which excess grease has to be removed. After degreasing, the specimen is handled with plastic tweezers or with clean protective gloves for the subsequent test. A note records that the purpose of this cleaning step is to remove foreign grease and skin secretions, that the step removes any lead contamination that may be present on the surface of the specimen, that where such lead contamination is itself to be tested the degreasing treatment is not carried out, and that omitting the cleaning procedure may affect the lead release of the specimen.

7.2 Preparation of the sample solution

The specimen is placed in a covered container and artificial saliva is added in the proportion of 1 mL per square centimetre according to the tested area of the specimen. The whole tested area is immersed in the artificial saliva, while the surfaces protected by wax or lacquer need not be immersed. The container is sealed with the tight cap to prevent the saliva from evaporating. The tested area of the specimen and the volume of artificial saliva used are recorded. Where the structure of the specimen is bulky, the volume of artificial saliva may be increased suitably so that the specimen is completely immersed.

The sealed container is placed in the constant temperature water bath shaker and shaken for (60 +/- 5) min. The shaken artificial saliva is transferred quantitatively to a suitable volumetric flask, the size of the flask being chosen with regard to the sensitivity of the instrument used to determine lead. To prevent the released lead from settling out again, a suitable amount of 10 % nitric acid solution by volume is added to the volumetric flask and the flask is diluted to the mark with water, so that the volume fraction of nitric acid in the solution is about 1 %; this gives the sample solution.

7.3 Preparation of the blank solution

Except that no specimen is added, the remaining steps follow 7.2.

7.5 Preparation of the calibration curve

The reference operating conditions of the instruments are given in Annex A. Under those conditions, or other suitable instrument operating conditions, the signal response values of lead in the lead series standard working solutions are measured with the inductively coupled plasma optical emission spectrometer, the graphite furnace atomic absorption spectrometer or the inductively coupled plasma mass spectrometer, in order of increasing mass concentration. When the inductively coupled plasma mass spectrometer is used, the bismuth internal standard working solution is injected at the same time as the lead series standard working solutions, giving the signal response ratio of lead to bismuth.

For determination with the inductively coupled plasma optical emission spectrometer or the graphite furnace atomic absorption spectrometer, the calibration curve is plotted with the lead mass concentration on the abscissa and the response signal value of the lead element on the ordinate; the linear correlation coefficient of the curve is calculated and is not less than 0.995.

For determination with the inductively coupled plasma mass spectrometer, the calibration curve is plotted with the lead mass concentration on the abscissa and the lead to bismuth response signal ratio on the ordinate; the linear correlation coefficient of the curve is calculated and is not less than 0.995.

7.6 Determination of the sample solution

Under the same instrument operating conditions as those used for the calibration curve, the blank solution and the sample solution are determined in turn with the inductively coupled plasma optical emission spectrometer, the graphite furnace atomic absorption spectrometer or the inductively coupled plasma mass spectrometer. When the inductively coupled plasma mass spectrometer is used, the internal standard working solution is added on line at the same time as the blank solution and the sample solution are injected, giving the corresponding lead to bismuth signal response ratio. The lead concentrations of the blank solution and of the sample solution are obtained from the lead calibration curve.

If the lead concentration of the sample solution is higher than the highest concentration of the lead calibration curve, the solution is diluted with 1 % nitric acid solution by volume and determined again, and the blank solution is diluted in parallel with it and determined.

8 Calculation and expression of the result

The lead release of the specimen per unit of time is calculated from the following quantities: the constant volume of the sample solution, in millilitres; the lead mass concentration of the sample solution and the lead mass concentration of the blank solution, both in micrograms per millilitre; the dilution factor; the tested area of the specimen, in square centimetres; and the time for which the specimen is shaken in the artificial saliva, one hour. The result is the lead release of the specimen, in micrograms per square centimetre per hour.

The arithmetic mean of the results of the determinations, calculated according to the number of specimens taken, is the test result, and the result is rounded to three decimal places.

9 Limit of quantification and precision

Limit of quantification: the limit of quantification of the method is 0.020 micrograms per square centimetre per hour.

Precision: in the same laboratory, by the same operator using the same equipment, according to the same test method and testing the same object independently within a short interval of time, the absolute value of the difference between the two independent test results obtained is not greater than 20 % of the arithmetic mean of the two determined values, on the premise that the cases exceeding 20 % of the arithmetic mean of the two determined values are not more than 5 %.

10 Test report

The test report includes at least the following: information on the specimen, including its source, the tested area and any other necessary description; the number of this document; a statement on sampling; a statement on the abrasion treatment, where applicable; the type of test instrument; the result of the lead release determination; the details of any departure from this document; and the date of the test.

A Annex A (informative) Reference operating conditions of the instruments

Table A.1 gives the operating conditions of the inductively coupled plasma optical emission spectrometer, in two pairs of instrument parameter and parameter value columns: incident power 1 150 W; plasma gas flow 12.5 L/min; auxiliary gas flow 0.5 L/min; nebuliser gas flow 0.6 L/min; peristaltic pump speed 45 r/min; spectral line wavelengths 220.3 nm and 261.4 nm.

Table A.2 gives the reference operating conditions of the graphite furnace atomic absorption spectrometer: spectral line wavelength 283.3 nm; slit 0.7 nm; lamp current 5 mA.

Table A.3 gives the reference conditions of the graphite furnace temperature programme, in three columns of step, temperature in degrees Celsius and heating rate in degrees Celsius per second: step 1, 110 °C, 5; step 2, 130 °C, 15; step 3, 850 °C, 10; step 4, 1 600 °C, 0; step 5, 2 450 °C, 1.

Table A.4 gives the reference operating conditions of the inductively coupled plasma mass spectrometer, in two pairs of instrument parameter and parameter value columns: lead analytical mass numbers 206, 207 and 208; determination mode, standard mode; cooling gas (argon) flow 14.0 L/min; auxiliary gas (argon) flow 0.8 L/min; carrier gas (argon) flow 1.0 L/min; bismuth analytical mass number 209; radiofrequency power 1 550 W; spray chamber temperature 2.7 °C; number of repetitions 3; dwell time 0.05 s.

B Bibliography

The bibliography lists one entry: FZ/T 01163, Determination of total lead and total cadmium content in textiles and their accessories - X-ray fluorescence spectrometry (XRF) analysis.