Textiles Determination of formaldehyde content

1 .Scope
This standard specifies the determination of the total amount of free formaldehyde extracted by hydrolysis.
This standard applies to any state of the textile test. This method is suitable for textiles with free formaldehyde content of between 20 mg / kg and 3500 mg / kg.
2 reference standard
The following standards contain provisions which, by reference in this standard, constitute provisions of this standard. At the time of publication of this standard, the versions shown are valid. All standards will be revised and the parties using this standard should explore the possibility of using the latest version of the following standards.
Standard atmospheres for temperature control and testing of textiles GB 6529-1986
Analysis of laboratory water specifications and test methods GB / T 6682-1992
3 .principle
After accurate weighing of the sample, in the 40 ℃ water bath for a certain period of time, from the fabric extraction of formaldehyde by water absorption, and then extract with acetylacetone color development, color liquid spectrophotometer colorimetric determination of its formaldehyde content.
4 .reagent
All reagents are of analytical grade and all water is of grade 3 water
Preparation of the sample
The sample does not require conditioning because the dryness and humidity associated with the humidity control can affect the amount of formaldehyde in the sample and store the sample into a container before testing.
Note: The sample can be stored in a polyethylene bag storage, outsourcing aluminum box, the reason is that this storage can prevent formaldehyde through the pores of the bag distribution. In addition, if the direct contact with the catalyst and other compounds left in the finished uncleaned fabric will react with the aluminum foil.
One g (accurate to 10 mg) of the cut sample was placed in a 250 mL stoichiometric flask or Erlenmeyer flask (5.2). Add 100mL of water, cover the lid, into the (40 soil 2) ℃ water bath (65 soil 2) min, shake the bottle every 5 min, filter (5.8) to another iodine bottle. If the formaldehyde content is too low, increase the sample volume to 2.5g to ensure the accuracy of the test.
If there is an objection, use a similarly modulated sample to calculate a correction factor for calibration in the experiment
Operating procedures
1 With a single pipette, 5 mL of the filtered sample solution and 5 mL of the standard formaldehyde solution were placed in a different tube (5.6) and shaken with 5 mL of acetylacetone solution (4.l).
2 first put the test tube (40 soil 2) ℃ water bath color (30 soil 2) min, and then removed, placed at room temperature (30 soil 5) min. An equal volume of acetylacetone was used as an empty white control with 5 mL of distilled water and the absorbance was measured at a wavelength of 412 nm at a spectrophotometer using a 10 mm absorption cell.
3 If the amount of formaldehyde extracted from the fabric is expected to exceed 500 mg / kg or the ratio is 5: 5 and the calculated value exceeds 500 mg / kg, the absorbance is diluted so that the absorbance is within the range of the working curve (in the calculation result, To consider dilution factors).
4 Taking into account the impure or fading of the sample solution, take 5 mL of the sample solution into another tube, add 5 mL of water (Chapter 4) instead of acetylacetone. The absorbance of this solution was treated and measured in the same manner as in 8.2 and water (Chapter 4) as a control.
5 do three parallel tests
Note: It will cause fading to expose the exposed yellow to the sun for a certain period of time. If the test tube has a significant delay (eg 1h) in the strong sunlight after the color is developed, it is necessary to take measures to protect the test tube, such as covering the tube with a cover that does not contain formaldehyde. Otherwise if the need to delay the reading, the color can be stable for some time (less overnight).
If the suspected absorption is not from formaldehyde but using, for example, a color reagent, a confirmation test (8.7) with double ketone.
Note 5: The reaction of bimethanone with formaldehyde will not see the color produced by the formaldehyde reaction.
 double ketone confirmation test: take 5mL sample solution into a test tube (if necessary, see, see 8.3), add 1mL bisphenol ethanol solution and shake the solution into the (40 ± 2) ℃ water bath (10 2) min, Add 5mL of acetylacetone reagent shaking, continue to put (40 ± 2) ℃ water bath (30 ± 2) min, take out the tube at room temperature (30 ± 2) min. The absorbance of the control solution prepared in the same manner was measured. The absorbance of the control solution with water instead of the sample solution, m from formaldehyde at 412 nm, disappeared.