GB/T 34673-2026Determination of heavy metal content in textile dyeing and finishing auxiliaries (English PDF)

4.1 Principle

After the specimen is digested with acid and hydrogen peroxide using microwave and then filtered, the emission intensity of the target heavy metal elements in the digestion solution is measured using inductively coupled plasma optical emission spectrometer at the corresponding analytical wavelengths. The concentrations of each heavy metal element are determined by referring to a standard working curve. The content of each heavy metal in the specimen is then calculated.

4.2 Reagents or materials

Unless otherwise specified, use only reagents that have been confirmed to be guaranteed reagents and Grade I water as specified in GB/T 6682.

4.2.1 Nitric acid. 65%~68% (mass fraction).

4.2.2 Hydrogen peroxide. 30% (mass fraction).

4.2.3 Fluoroboric acid. greater than 40% (mass fraction).

4.2.4 Nitric acid solution, 3% (volume fraction). take 30 mL of nitric acid (4.2.1), slowly add it to 970 mL of water, and mix well.

4.2.5 Heavy metal single-element standard stock solution or multi-element mixed standard stock solution, 1000 µg/mL. commercially available certified reference materials or standard samples. NOTE: For information on the storage environment and validity period of commercially available certified reference materials or standard samples, please refer to the relevant certificate.

4.2.6 Series of mixed element standard working solutions. take appropriate amounts of heavy metal single-element standard stock solutions or multi-element mixed standard stock solutions (4.2.5). Dilute stepwise with nitric acid solution (4.2.4) to prepare a series of mixed element standard working solutions. The series concentrations of each element are shown in Table A.1 of Annex A. NOTE 1: The series of mixed element standard working solutions (4.2.6) should be stored in polyethylene bottles at 0°C ~ 4°C, protected from light. Shelf life is one month. NOTE 2: Based on the concentration levels of each element in the specimen, the concentrations of each element in the series of mixed element standard working solutions (4.2.6) are adjusted appropriately.

4.2.7 Argon. purity is greater than or equal to 99.995% (volume fraction).

4.3 Instruments and equipment

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

4.3.2 Analytical balance. sensitivity is 0.001 g.

4.3.3 Microwave digestion apparatus. with programmed temperature control function; temperature control range is room temperature to 200°C, temperature control accuracy is ±3°C (less than or equal to 100°C), ±5°C (100°C~200°C); equipped with polytetrafluoroethylene (PTFE) digestion vessel.

4.3.4 Volumetric flasks. select volumetric flasks of appropriate volume according to the needs of use.

4.3.5 Aqueous phase filter membrane. pore size is 0.45 µm.

4.3.6 Pipettes. select the appropriate volume range according to the usage requirements; disposable pipette tips are provided.

4.4 Test procedures

4.4.1 Specimen processing

Accurately weigh 0.200 g~0.250 g (accurate to 0.001 g) of specimen into a microwave digestion vessel. Add 4 mL of nitric acid (4.2.1), 2 mL of hydrogen peroxide (4.2.2), and 2 mL of fluoroboric acid (4.2.3). Seal the microwave digestion vessel. Perform microwave digestion using a microwave digester according to the microwave digestion temperature program in Table 1. After the program is completed, allow it to stand.

Remove the vessel after the temperature has dropped to room temperature. Slowly open the vessel lid to release the gas. Transfer the digestion solution to a 25 mL volumetric flask. Rinse the inner vessel and inner lid of the digestion vessel three times with a small amount of water. Combine the rinsing solutions in the volumetric flask. Dilute to the mark with water and mix well. Then filter the solution through an aqueous filter membrane and analyze it using inductively coupled plasma optical emission spectrometer.

4.4.2 Analytical methods

4.4.2.1 Analysis conditions

Because test results depend on the instrument used, it is impossible to provide universal parameters for instrumental analysis. The instrument reference conditions listed in Annex B have been proven suitable for the tests. Inductively coupled plasma optical emission spectrometer (ICP-OES) instrument parameters are shown in Table B.1.

Recommended analytical spectral lines for the analytes are shown in Table B.2.

4.4.2.2 Plotting the standard working curve

The determination is carried out according to the analytical conditions in 4.4.2.1. The spectral intensities of each analyte in a series of mixed element standard working solutions (4.2.6) are measured in order of increasing concentration. The standard working curve is plotted with the spectral intensity as the ordinate and the concentration of the analyte as the abscissa.

4.4.2.3 Determination of specimen solution

According to the analytical conditions in 4.4.2.1, the spectral intensity of each analyte in the specimen solution is determined, and the concentration of each analyte is calculated from the standard working curve.

4.4.3 Blank test

Except for the absence of a sample, proceed according to steps 4.4.1~4.4.2.

5.1 Principle

After acid microwave digestion and filtration, the specimen is analyzed using inductively coupled plasma mass spectrometer. Qualitative analysis is performed using the specific mass number (mass-to-charge ratio, m/z) of the element, and quantitative analysis is performed using the ratio of the intensity of the mass spectrometry signal of the analyte to that of the internal standard element, which is proportional to the concentration of the analyte.

5.2 Reagents or materials

Unless otherwise specified, use only reagents that have been confirmed to be guaranteed reagents and Grade I water as specified in GB/T 6682.

5.2.1 Nitric acid. 65%~68% (mass fraction).

5.2.2 Hydrofluoric acid.

5.2.3 L-cysteine hydrochloride monohydrate (CAS No.: 7048-04-6). >=99% (mass fraction).

5.2.4 Gold (Au) elemental standard solution, 1000 µg/mL. commercially available certified reference material or standard sample.

5.2.5 Nitric acid solution, 5% (volume fraction). take 50 mL of nitric acid (5.2.1) and slowly add it to 950 mL of water, then mix well.

5.2.6 Mercury standard dilution solution I. weigh 2.0 g (accurate to 0.01 g) of L-cysteine hydrochloride monohydrate (5.2.3), dissolve and dilute to 1000 mL with nitric acid solution (5.2.5).

5.2.7 Mercury standard dilute solution II. pipette 0.2 mL of gold (Au) element standard solution (5.2.4), and dilute to 1000 mL with nitric acid solution (5.2.5).

5.2.8 Single-element heavy metal standard stock solution or multi-element mixed standard stock solution, 1000 µg/mL. commercially available certified reference materials or standard samples.

NOTE: For information on the storage environment and validity period of commercially available certified reference materials or standard samples, please refer to the relevant certificate.

5.2.9 Series of mixed element standard working solutions. except for mercury (Hg), take appropriate amounts of each heavy metal single-element standard stock solution or multi-element mixed standard stock solution (5.2.8). Dilute stepwise with nitric acid solution (5.2.5) to prepare a series of mixed element standard working solutions. The series concentrations of each element are shown in Table A.2. Prepare when needed.

NOTE: Based on the concentration levels of each element in the specimen, the concentrations of each element in the series of mixed element standard working solutions (5.2.9) are adjusted appropriately.

5.2.10 Mercury (Hg) element standard working solutions. transfer an appropriate amount of mercury (Hg) element standard stock solution (5.2.8). Dilute stepwise with mercury standard dilution solution I (5.2.6) or mercury standard dilution solution II (5.2.7) to prepare a series of mercury (Hg) element standard working solutions. The series concentrations are shown in Table A.2. Prepare when needed.

NOTE: Based on the mercury (Hg) concentration level in the specimen, adjust the concentration in the series standard working solutions of mercury (Hg) appropriately (5.2.10).

5.2.11 Internal standard single-element standard stock solution or internal standard multi-element mixed standard stock solution, 100 µg/mL. commercially available certified reference materials or standard samples; recommended internal standard elements for each analyte are shown in Table C.4.

NOTE: For information on the storage environment and validity period of commercially available certified reference materials or standard samples, please refer to the relevant certificate.

5.2.12 Internal standard working solution. transfer an appropriate amount of internal standard single element stock solution or internal standard multi-element mixed standard stock solution (5.2.11). Dilute with nitric acid solution (5.2.5) to prepare an internal standard working solution of appropriate concentration. Since different instruments use peristaltic pump tubing with varying inner diameters, the concentration of the internal standard element in the sample solution must be considered when adding the internal standard online. The reference concentration range for the internal standard element after sample solution mixing is 0.025 µg/mL~0.5 µg/mL. For internal standard elements with low mass numbers, the working solution concentration can be appropriately increased.

NOTE: The internal standard working solution (5.2.12) should be stored in a polyethylene bottle at 0°C~4°C, protected from light. The shelf life is 3 months.

5.2.13 Argon. purity is greater than or equal to 99.995% (volume fraction).

5.2.14 Helium. purity is greater than or equal to 99.995% (volume fraction).

5.3 Instruments and equipment

5.3.1 Inductively coupled plasma mass spectrometer (ICP-MS).

5.3.2 Analytical balance. sensitivity is 0.001 g.

5.3.3 Microwave digestion apparatus. with programmed temperature control function; temperature control range is room temperature to 200°C, temperature control accuracy is ±3°C (less than or equal to 100°C), ±5°C (100°C~200°C); equipped with polytetrafluoroethylene (PTFE) digestion vessel.

5.3.4 Acid removal device. with temperature control function, with a maximum operating temperature greater than or equal to 150°C and a temperature control accuracy of ±1°C.

5.3.5 Volumetric flasks. select volumetric flasks of appropriate volume according to usage requirements.

5.3.6 Aqueous filter membrane. pore size is 0.45 µm.

5.3.7 Pipette. select the appropriate volume range according to usage requirements; equipped with disposable pipette tips.

5.4 Test procedures

5.4.1 Specimen processing

Accurately weigh 0.200 g to 0.300 g (accurate to 0.001 g) of specimen into a digestion vessel. Add 5 mL of nitric acid (5.2.1) and 2 mL of hydrofluoric acid (5.2.2). Seal the microwave digestion vessel. Perform microwave digestion using a microwave digester […]