GB/T 42700-2023Textiles - Determination of total content of boron (English PDF)

1 Scope

GB/T 42700-2023 gives the method for measuring total boron in textiles. Boron reaches fabric from several directions - flame retardant treatments, some finishing agents and dyeing auxiliaries, and borate-containing detergents and processing chemicals - and boron compounds are classified as reproductive toxicants in the European Union, which has put them onto restricted substance lists and therefore into the supply chain requirements that Chinese textile exporters have to satisfy. Measuring the total content, rather than a particular compound, is the practical choice: it does not depend on knowing which boron-bearing chemical was used, which a testing laboratory receiving a finished garment generally does not. This document describes a method for determining the total boron content in textiles using inductively coupled plasma optical emission spectrometry (ICP-OES), a technique suited to trace-level determination after digestion of the sample. It applies to various textile materials and their products. Under ICS 59.080.01, it is written for textile testing laboratories, for brands and retailers running restricted substance programmes, and for the finishers and manufacturers who must demonstrate compliance.

This document describes a method for the determination of the total content of boron in textiles using an inductively coupled plasma optical emission spectrometer (ICP- OES). This document applies to various textile materials and their products.

2 Normative references

The following documents contain the provisions which, through normative reference in this document, constitute the essential provisions of this document. For the dated referenced documents, only the versions with the indicated dates are applicable to this document; for the undated referenced documents, only the latest version (including all the amendments) is applicable to this document.

GB/T 6682 Water for analytical laboratory use - Specification and test methods

3 Terms and definitions

There are no terms and definitions that need to be defined in this document.

4 Principle

After the sample is digested by concentrated nitric acid-hydrogen peroxide microwave, the digestion solution is diluted to the metered volume, and the emission intensities of boron and internal standard yttrium are measured by inductively coupled plasma optical emission spectrometer (ICP-OES). The internal standard method is used for quantification, the concentration of boron is determined according to the standard working curve, and the total content of boron in the sample is calculated.

5 Reagents and materials

5.1 Water: Water shall meet the requirements of GB/T 6682, grade 2 or above.

5.2 Concentrated nitric acid: The concentration is 65% (mass fraction); a guaranteed reagent.

5.3 Nitric acid solution: The concentration is 5% (volume fraction); measure 50 mL of concentrated nitric acid (5.2), and dilute it to 1000 mL with water (5.1).

5.4 Hydrogen peroxide: The concentration is 30% (mass fraction), a guaranteed reagent.

5.5 Boron (B) standard substance: CAS. No7440-42-8, and the mass concentration is 1000 mg/L.

5.6 Yttrium (Y) standard substance: CAS. No7440-65-5, and the mass concentration is 1000 mg/L, internal standard substance.

5.7 Boron standard stock solution: Accurately measure an appropriate amount of boron standard substance (5.5), and use nitric acid solution (5.3) to prepare a boron standard stock solution with a mass concentration of 10 mg/L.

5.8 Internal standard yttrium standard stock solution: Accurately measure an appropriate amount of yttrium standard substance (5.6), and use nitric acid solution (5.3) to prepare a yttrium standard stock solution with a mass concentration of 10 mg/L. NOTE: The validity period of the standard stock solution is 6 months when stored in the dark at 0 °C~4 °C. When turbidity, precipitation, or color change occurs, prepare it again.

5.9 Standard working solution: Dilute boron standard stock solution (5.7) with nitric acid solution (5.3) as needed to form a series of standard working solutions of different concentrations (all contain

0.10 mg/L yttrium standard solution). NOTE: The standard working solution is valid for 3 months when stored in the dark at 0 °C~4 °C. When turbidity, precipitation, or color change occurs, prepare it again.

6 Instruments and equipment

6.1 Inductively coupled plasma optical emission spectrometer (ICP-OES).

6.2 Microwave digestion instrument: temperature sensing type.

6.3 PTFE digestion vessel.

6.4 Analytical balance: The division value is 0.0001 g.

c) Auxiliary gas flow rate:

0.2 L/min;

d) Atomizing gas flow rate:

0.65 L/min;

e) Vibration pump flow rate:

f) Wavelength of boron analytical spectral line: 249.772 nm;

g) Wavelength of yttrium analytical spectral line: 371.029 nm.

7 Analysis steps...

8 Calculation and presentation of the result

8.1 Calculation of the result The content of boron in the sample is calculated according to formula (1). where: X -- the total content of boron in the sample, in milligrams per kilogram (mg/kg); C -- the mass concentration of boron in the sample solution, in milligrams per liter (mg/L); C0 -- the mass concentration of boron in the blank solution, in milligrams per liter (mg/L); V -- the metered volume of the sample solution, in milliliters (mL); m -- the mass of the sample, in grams (g).

8.2 Result presentation The mean of two parallel determination results is taken as the test result, and the result is rounded to one decimal place. When it is lower than the limit of quantification, the test result is "not detected".

9 Limit of quantitation, recovery, and precision

9.1 Limit of quantitation The limit of quantitation is

9.2 Recovery The standard addition method is used, and the measured recovery shall be greater than 80%.

9.3 Precision In the same laboratory, the same operator uses the same equipment, according to the same test method, and independently tests the same measured object twice in a short period of time; the relative standard deviation of the two test results obtained is not more than 10%, the probability of greater than 10% is not more than 5% is the premise.

10 Test report

The test report shall at least include the following information:

a) the number of this document;