Warning: the personnel using this standard shall have practical experience in laboratory work. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions.
1 Scope
This standard specifies the determination method of formaldehyde in dye products.
This standard is applicable to the determination of formaldehyde in dye products.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 601 Chemical reagent—Preparations of reference titration solutions
GB/T 6682-2008 Water for analytical laboratory use—Specification and test methods (ISO 3696: 1987, MOD).
GB/T 8170-2008 Rules of rounding off for numerical values & expression and judgment of limiting values
3 Test methods
3.1 Spectrophotometry (arbitration method)
3.1.1 Principle
The free formaldehyde in the sample was distilled to prepare an aqueous solution, which was developed with acetylacetone and determined by spectrophotometer colorimetry.
3.1.2 Determination method
3.1.2.1 General
Unless otherwise specified, only recognized analytical reagent and Grade 3 water (specified in GB/T 6682-2008) shall be used. Unless otherwise specified, the standard volumetric solutions used in the test shall be prepared and calibrated according to the requirements of GB/T 601. Judgment of the inspection result shall be carried out according to the rounding-off value by comparison method specified in GB/T 8170-2008, 4.3.3.
3.1.2.2 Reagents and solutions
3.1.2.2.1 Ammonium acetate.
3.1.2.2.2 Acetic acid.
3.1.2.2.3 Acetylacetone.
3.1.2.2.4 Formaldehyde: with a concentration of about 37% (mass fraction).
3.1.2.2.5 Acetylacetone solution: weigh 150 g of ammonium acetate, dissolve it with 800 mL of water, transfer it into a 1,000 mL brown volumetric flask, then add 3 mL of acetic acid and 2 mL of acetylacetone, dilute it to the scale with water, and store it at 0°C ~ 5°C away from light. After 12 h of storage, the color gradually darkens. Therefore, it shall be stored for 12 h before use, and the solution will be effective within 6 ~ 8 weeks. After long-term storage, its sensitivity will change slightly, thus the calibration curve shall be checked weekly, or the absorbance shall be measured at 412 nm with water as the reference solution prior to use and shall be less than 0.015, otherwise it needs to be prepared again.
3.1.2.3 Apparatuses
3.1.2.3.1 500 mL distillation flask, condensing tube and fraction collector.
3.1.2.3.2 Volumetric flasks: 100 mL, 250 mL and 1,000 mL.
3.1.2.3.3 Colorimetric tube with stopper: 25 mL.
3.1.2.3.4 Cuvette: 10 mm.
3.1.2.3.5 Spectrophotometer.
GB/T 23973-2018 The following standards are cited：
