GB/T 19941.1-2019Leather and fur—Determination of formaldehyde content—Part 1: High performance liquid chromatography method (English PDF)

8.2.1 of this Edition; 6.2 of Edition 2019);

- The conditions (such as temperature and time) for the reaction of formaldehyde

with DNPH have been changed (see 8.2.2 of this Edition; 6.3 of Edition 2019);

- The method for creating the standard working curve has been changed (see 8.2.4

of this Edition; 6.5 of Edition 2019);

- The preparation method of formaldehyde standard solution when using

formaldehyde stock solution to create a standard working curve has been

modified (see 8.2.4.1 of this Edition; 6.5.1 of Edition 2019);

- The requirement regarding the solution standing time when preparing a standard

working curve using DNPH-formaldehyde solution has been deleted (see 6.5.2 of

Edition 2019);

Leather and fur -- Determination of formaldehyde content --

Part 1.High-performance liquid chromatography method

5.1 Unless otherwise specified, all reagents used are analytically pure. The water used

in the tests shall meet the requirements for Grade III water in GB/T 6682, and all

solutions used shall be aqueous solutions.

5.2 Formaldehyde solution. the mass fraction is approximately 37%.

NOTE. Formaldehyde and formaldehyde-2,4-dinitrophenyl ether solutions are commercially

available. If using commercially available solutions, procedure 8.1 is unnecessary.

5.3 Iodine solution. 0.05 mol/L, which means it contains 12.68 g of iodine per liter.

5.4 Sodium hydroxide (NaOH) solution. 2.0 mol/L.

5.5 Sulfuric acid (H2SO4) solution. 2.0 mol/L.

5.6 Sodium thiosulfate (Na2S2O3) solution. 0.1 mol/L.

5.7 Starch solution. 1% by mass, that is, 1 g of starch are dissolved in 100 mL of water.

5.8 Acetonitrile. chromatographically pure.

5.9 Extraction solution. 0.1% by mass, i.e., 1 g of sodium dodecyl sulfonate or sodium

dodecyl sulfate are dissolved in 1000 mL of water.

5.10 2,4-Dinitrophenylhydrazine (DNPH) solution. dissolve 0.3 g of DNPH (2,4-

dinitrophenylhydrazine) in 100 mL of acetonitrile (5.8).

6.1 Volumetric flasks. 10 mL, 500 mL and 1000 mL.

6.2 Erlenmeyer flasks. with stoppers or screw caps, 100 mL and 250 mL.

6.3 Glass fiber filter. GF8 (or glass filter G3, diameter is 70 mm~100 mm).

6.4 Water bath. temperature controllable up to (40 ± 2)°C, equipped with an oscillation

device with an oscillation frequency of (50 ± 10) r/min.

6.5 Water bath or oven. temperature controllable up to (50 ± 2)°C.

6.6 High performance liquid chromatograph. equipped with a UV detector or diode

array detector.

6.7 Membrane filters. such as polyamide membranes, with a pore size of 0.45µm.

6.8 Analytical balance. scale division value is 0.1 mg.

7.1 Sampling

The leather is manufactured in accordance with GB/T 39364.

The sampling of fur shall be conducted in accordance with the provisions of QB/T 1267.

During the sampling process, care shall be taken to avoid damage to the fur and to keep

the fur intact.

If sampling cannot be taken from a standard location (such as directly from shoes or

clothing), specimens shall be taken from any location within the available area. The

samples shall be representative, and this shall be noted in the test report.

Residual glue on the sample shall be removed by physical methods.

7.2 Specimen preparation

The leather shall be manufactured in accordance with the provisions of QB/T 2716.

The fur shall be tested in accordance with the provisions of QB/T 1272.The test

specimen shall be tested together with the fur.

If the test results are based on the oven-dry weight of the specimen, the volatile content

of another leather or fur specimen shall be determined in accordance with the provisions

of QB/T 2717 or QB/T 1273.

8.1 Determination of formaldehyde content in stock solution

8.1.1 Preparation of formaldehyde stock solution

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