GB/T 2912.1-1998 Determination of formaldehyde in textiles Part 1: Free and hydrolyzed formaldehyde (water extraction method)
Some standard content:
GB/T 2912.1-1998
After various dyeing and finishing processes (resin finishing, color fixation, paint printing, etc.), fabrics will release formaldehyde to varying degrees during wearing and storage under the influence of temperature and humidity, polluting the environment, irritating the human body, and affecting health. Many countries strictly control the release of formaldehyde from fabrics.
This standard is equivalent to ISO/FDIS14184-1:1997 Determination of formaldehyde in textiles Part 1: Free hydrolyzed formaldehyde (water extraction method)".
GB/T2912.2-1998 provides a method for determining the release of formaldehyde. In addition to slight changes in the working curve concentration range of the formaldehyde standard solution, the sample preservation method, and the use time after the trial preparation of acetylacetone, this standard also adds the content that when it is suspected that the color developed is not from formaldehyde, a confirmation test can be carried out with dimedone ethanol solution.
Appendix A of this standard is the standard appendix, and Appendix B is the indicative appendix. This standard replaces GB/T2912-1982 from the date of entry into force. This standard was proposed by the former China National Textile and Apparel Council. This standard is under the jurisdiction of the Basic Standards Branch of the National Technical Committee for Textile Standardization. The drafting unit of this standard is Shanghai Textile Science Research Institute. The main drafter of this standard is Zhou Jinghua.
0 Warning
National Standard of the People's Republic of China
Textiles
Determination of formaldehyde--Part 1 :
Free and hydrolized formaldehyde(Water extraction method)
GB/T 2912.1—1998
Replaces GB/T 2912-1982
The substances and procedures used in this standard may cause health hazards if appropriate precautions are not taken. This refers only to technical suitability, and the user still bears the legal responsibility for health and safety at any stage. The personnel who implement this provision must be qualified and experienced.
1 Scope
This standard specifies the method for the determination of the total amount of free formaldehyde extracted by hydrolysis. This standard is applicable to the testing of textiles in any state. This method is applicable to textiles with free formaldehyde content between 20mg/kg and 3500mg/kg.
2 Referenced standards
The provisions contained in the following standards are constituted as provisions of this standard by reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB6529-1986 Standard atmosphere for humidity conditioning and testing of textiles GB/T6682-1992 Specification and test methods for water used in analytical laboratories 3 Principle
The accurately weighed sample is extracted in a 40℃ water bath for a certain period of time. The formaldehyde extracted from the fabric is absorbed by water, and then the extract is colorized with acetylacetone, and the color-developing solution is colorimetrically determined by a spectrophotometer to determine its formaldehyde content. 4 Reagents
All reagents are analytically pure, and all water is grade 3 water (GB/T6682-1992). 4.1 Acetylacetone reagent (Nessler's reagent)
Add 150% ammonium acetate to a 1000mL volumetric flask, dissolve it with 800mL water, then add 3mL glacial acetic acid and 2mL acetylacetone, dilute to the mark with water, and store in a brown bottle. Note 1: The color gradually changes to yellow after 12 hours of storage. Therefore, it must be stored for 12 hours before use. The reagent is valid for 6 weeks. After long-term storage, its sensitivity will change slightly, so a calibration curve should be drawn every period to calibrate with the standard curve. 4.2 Formaldehyde solution, concentration of about 37% (m/V or m/m). 4.3 Dimedone ethanol solution Approved by the State Administration of Quality and Technical Supervision on November 26, 1998 24
Implemented on May 1, 1999
GB/T 2912. 1-1998
Dissolve 1g of dimedone (dimethyl-dihydroxy-resorcinol or 5,5-dimethyl-cyclohexanedione) in ethanol and dilute to 100mL. Prepare immediately before use.
5 Equipment
5. 1 50mL, 250mL, 500mL, 1000mL volumetric flasks. 5. 2 250mL iodine volumetric flask or Erlenmeyer flask with lid. 5. 3 1mL, 5mL, 10mL and 25mL single-marked pipettes and 5mL graduated pipettes. Note 2: An automatic liquid transfer system with the same accuracy as a manual pipette can be used. 5. 4 10mL, 50mL graduated cylinder.
5.5 Spectrophotometer (wavelength 412nm). 5.6 Test tubes and test tube racks.
5.7 Constant temperature water bath, (40±2)℃. 5.8 No. 2 glass funnel filter.
5.9 Balance, accurate to 0.2mg.
6 Preparation and calibration of formaldehyde standard solution
6.1 Preparation of about 1500μg/mL formaldehyde stock solution: dilute 3.8mL formaldehyde solution (4.2) to 1L with water, and measure the concentration of formaldehyde stock solution by standard method (see Appendix A). Record the exact concentration of the standard stock solution, which can be stored for four weeks and used to prepare standard dilutions. 6.2 Dilution
If 1 test sample and 100mL water are used, the corresponding formaldehyde concentration in the test sample will be 100 times the exact concentration in the standard solution. 6.2.1 Preparation of standard solution (S2)
Dilute 10 mL of the titrated standard stock solution (containing 1.5 mg/mL formaldehyde) prepared in accordance with 6.1 to 200 mL with water in a volumetric flask. This solution contains 75 mg/L formaldehyde. wwW.bzxz.Net
6.2.2 Preparation of calibration solution
Prepare the calibration solution based on the standard solution (S2). Dilute at least 5 of the following solutions with water in a 500mL volumetric flask: 1mL S2 to 500mL, contains 0.15μg formaldehyde/mL = 15mg formaldehyde/kg fabric 2mL S2 to 500mL, contains 0.30μg formaldehyde/mL = 30mg formaldehyde/kg fabric 5mL S2 to 500mL, contains 0.75μg formaldehyde/mL = 75mg formaldehyde/kg fabric 10mL S2 to 500mL, contains 1.50μg formaldehyde/mL = 150mg formaldehyde/kg fabric 15mL S2 to 500mL, contains 2.25μg formaldehyde/mL=225mg formaldehyde/kg fabric 20mL S2 to 500mL, including 3.00μg formaldehyde/mL=300mg formaldehyde/kg fabric 30mL S2 to 500mL, including 4.50μg formaldehyde/mL450mg formaldehyde/kg fabric 40mL S2 to 500mL, including 6.00p formaldehyde/mL=600mg formaldehyde/kg fabric Calculate the working curve y=a+bx, this curve is used for all measured values, if the formaldehyde content in the test sample is higher than 500mg/kg, dilute the sample solution.
Note 3; If the formaldehyde concentration in the calibration solution is to be the same as the concentration in the fabric test solution, double dilution is required. If there is 20 mg formaldehyde in each kilogram of fabric, 1. 00g of sample solution extracted with 100 mL of water contains 20 μg formaldehyde, and so on, the formaldehyde content in 1 mL of test solution is 0. 2 pg.
7 Preparation of samples
The samples do not need to be conditioned, because the dryness and humidity associated with conditioning can affect the formaldehyde content in the samples. Before testing, the samples are stored in a container.
Note 4: The samples can be stored in a vinyl bag and wrapped in an aluminum box. The reason for this is that such storage can prevent formaldehyde from emitting through the pores of the bag. In addition, if the sample is directly conditioned, the catalyst and other compounds left on the treated unwashed fabric will react with the alkali. 1g (accurate to 10mg) of the chopped sample is placed in a 250mL stoppered iodine bottle or conical flask (5.2), 100mL of water is added, the lid is tightly closed, and the sample is placed in a (40±2)℃ water bath for (60±5)min. The bottle is shaken once every 5min and filtered into another iodine bottle using a filter (5.8). If the formaldehyde content is too low, increase the sample weight to 2.5 g to ensure the accuracy of the test. If there is any objection, use a conditioned sample to calculate a correction factor for the sample used in the test. Weigh the test sample cut from the sample immediately and weigh it again after conditioning (according to GB6529). Use these values to calculate the correction factor for calculating the mass of the conditioned sample used in the sample solution. 8 Operation procedure
8.1 Use a single-mark pipette to draw 5 mL of the filtered sample solution and 5 mL of the standard formaldehyde solution into different test tubes (5.6), and add 5 mL of acetylacetone solution (4.1) to each tube and shake. 8.2 First, place the test tube in a (40 ± 2) ℃ water bath for color development for (30 ± 5) min, then take it out and place it at room temperature for (30 ± 5) min. Use 5 mL of distilled water and an equal volume of acetylacetone as a blank control, and use a 10 mm absorption cell to measure the absorbance at a wavelength of 412 nm on a spectrophotometer. 8.3 If the expected amount of formaldehyde extracted from the fabric exceeds 500 mg/kg, or the test adopts a 5:5 ratio and the calculated value exceeds 500 mg/kg, dilute the extract so that its absorbance is within the range of the working curve (the dilution factor should be considered when calculating the results). 8.4 Considering the impurity or discoloration of the sample solution, take 5 mL of the sample solution and place it in another test tube. Add 5 mL of water (Chapter 4) instead of acetylacetone. Treat and measure the absorbance of this solution in the same way as in 8.2, using water (Chapter 4) as a control. 8.5 Perform three parallel tests
Note: Exposing the developed yellow color to sunlight for a certain period of time will cause fading. If the test tube reading is significantly delayed (for example, 1 hour) after color development in strong sunlight, measures should be taken to protect the test tube, such as covering the test tube with a cover that does not contain formaldehyde. Otherwise, if a delay in reading is required, the color can be stable for a period of time (at least overnight). 8.6 If it is suspected that the absorption is not from formaldehyde but is caused by a reagent that has a chromophore, for example, a confirmation test (8.7) is performed using dimedone. Note 5: Dimedone reacts with formaldehyde, and the color produced by the reaction with formaldehyde will not be seen. 8.7 Dimedone confirmation test: Take 5mL of sample solution into a test tube (dilute if necessary, see 8.3), add 1mL of dimedone ethanol solution and shake, place the solution in a (40±2)℃ water bath for (10±1)min, add 5mL of acetylacetone reagent and shake, continue to place in a (40±2)℃ water bath for (30±5)min, take out the test tube and place it at room temperature for (30±5)min. Measure the absorbance of the control solution prepared in the same way, but use water (Chapter 4) instead of the sample solution, and the absorbance from formaldehyde at 412nm will disappear. 9. Calculation and expression of results
Each test sample is corrected for sample absorbance using formula (1): A = A — Ab — (Aa)
Where: A — corrected absorbance;
A. — absorbance measured in the test sample; A. — absorbance measured in the blank reagent;
Aa — absorbance measured in the blank sample (only used in the case of discoloration or staining). Use the corrected absorbance value to find out the formaldehyde content through the working curve and express it in μg/mL. Use formula (2) to calculate the amount of formaldehyde extracted from each sample: F = X100
Where: F — formaldehyde content extracted from the fabric sample, mg/kg; c — formaldehyde content in the extract read from the working curve, mg/L; m — mass of the sample, g.
Calculate the average of the three results.
Test report
The test report shall include the following contents:
a) This standard number
GB/T 2912. 1-1998
b) Sample date, storage method before test and test date; c) Description and packaging method of test sample; d) Total amount of test sample and correction factor; e) Range of working curve;
f) Formaldehyde content extracted from sample, mg/kg; g) Deviation caused by specified procedure.
A1 Total determination
GB/T 2912. 1-1998
(Annex of standard)
Standardization of formaldehyde stock solution
Formaldehyde stock solution with a content of about 1500μg/mL must be accurately standardized in order to make an accurate working curve for colorimetric analysis.
A2 Principle
An aliquot of the stock solution is reacted with an excess of sodium sulfite and back-titrated with a standard acid solution under the indication of thymol acid. A3 Equipment
A3. 110 mL single-marked pipette.
A3. 250 mL single-marked pipette.
A3. 350 mL burette.
A3. 4150 mL conical flask.
A4 Reagents
A4.1 Sodium sulfite [c(NazSO.) = 1 mol/L: Dissolve 126 g of anhydrous sodium sulfite per liter of water (Chapter 4). A4.2 Thymolphthalein indicator: Dissolve 10 g of thymol acid in 1 L of ethanol solution. A4. 3 Sulfuric acid: c(H,SO,) -0. 01 mol/L. Note: It can be purchased from a chemical supply company or calibrated with standard sodium hydroxide solution. Procedure
Pipette 50 mL of sodium sulfite (A4.1) into a conical flask (A3.4), add 2 drops of thymol acid indicator (A4.2), and if necessary, add a few drops of sulfuric acid (A4.3) until the blue color disappears.
Pipette 10 mL of formaldehyde stock solution into the flask (the blue color will reappear), and titrate with sulfuric acid (A4.3) until the blue color disappears, and record the volume of acid used. Note
The volume of sulfuric acid solution is about 25 mL.
2 The pH correction value can be used instead of the thymol acid indicator, in which case the final point is pH = 9.5. The above procedure is repeated once.
A6 Calculation
1 mL 0.01 mol1/L sulfuric acid is equivalent to 0.6 mg formaldehyde. Calculate the formaldehyde concentration in the stock solution using formula (A1): Amount of sulfuric acid (mL) × 0.6 × 1000
Formaldehyde concentration (μg/mL) -
Amount of formaldehyde stock solution (mL)
Calculate the average value of the results, and use the concentration obtained according to formula (A1) to draw a working curve for colorimetric analysis. 28
GB/T2912.1—1998
Appendix B
(Suggestive Appendix)
Method precision references
This standard test method is based on a Finnish method, and the precision of its test depends on the formaldehyde content of the sample. Formaldehyde content, mg/kg
The change in formaldehyde content below 20 mg/kg is not noticeable. Precision, %
Note: The calibration curve in the GB/T2912.1 method is different from the curve made using the results mentioned above. 29—absorbance measured in the test sample; A-absorbance measured in the blank reagent,
Aa——absorbance measured in the blank sample (only used in the case of discoloration or staining). Use the corrected absorbance value to find the formaldehyde content through the working curve, expressed in μg/mL. Use formula (2) to calculate the amount of formaldehyde extracted from each sample: F=X100
Where: F-formaldehyde content extracted from the fabric sample, mg/kg; c---formaldehyde content in the extract read from the working curve, mg/L; m-mass of the sample, g.
Calculate the average of the three results.
Test report
The test report shall include the following contents:
a) This standard number
GB/T 2912. 1-1998
b) Sample date, storage method before test and test date; c) Description and packaging method of test sample; d) Total amount of test sample and correction factor; e) Range of working curve;
f) Formaldehyde content extracted from sample, mg/kg; g) Deviation caused by specified procedure.
A1 Total determination
GB/T 2912. 1-1998
(Annex of standard)
Standardization of formaldehyde stock solution
Formaldehyde stock solution with a content of about 1500μg/mL must be accurately standardized in order to make an accurate working curve for colorimetric analysis.
A2 Principle
An aliquot of the stock solution is reacted with an excess of sodium sulfite and back-titrated with a standard acid solution under the indication of thymol acid. A3 Equipment
A3. 110 mL single-marked pipette.
A3. 250 mL single-marked pipette.
A3. 350 mL burette.
A3. 4150 mL conical flask.
A4 Reagents
A4.1 Sodium sulfite [c(NazSO.) = 1 mol/L: Dissolve 126 g of anhydrous sodium sulfite per liter of water (Chapter 4). A4.2 Thymolphthalein indicator: Dissolve 10 g of thymol acid in 1 L of ethanol solution. A4. 3 Sulfuric acid: c(H,SO,) -0. 01 mol/L. Note: It can be purchased from a chemical supply company or calibrated with standard sodium hydroxide solution. Procedure
Pipette 50 mL of sodium sulfite (A4.1) into a conical flask (A3.4), add 2 drops of thymol acid indicator (A4.2), and if necessary, add a few drops of sulfuric acid (A4.3) until the blue color disappears.
Pipette 10 mL of formaldehyde stock solution into the flask (the blue color will reappear), and titrate with sulfuric acid (A4.3) until the blue color disappears, and record the volume of acid used. Note
The volume of sulfuric acid solution is about 25 mL.
2 The pH correction value can be used instead of the thymol acid indicator, in which case the final point is pH = 9.5. The above procedure is repeated once.
A6 Calculation
1 mL 0.01 mol1/L sulfuric acid is equivalent to 0.6 mg formaldehyde. Calculate the formaldehyde concentration in the stock solution using formula (A1): Amount of sulfuric acid (mL) × 0.6 × 1000
Formaldehyde concentration (μg/mL) -
Amount of formaldehyde stock solution (mL)
Calculate the average value of the results, and use the concentration obtained according to formula (A1) to draw a working curve for colorimetric analysis. 28
GB/T2912.1—1998
Appendix B
(Suggestive Appendix)
Method precision references
This standard test method is based on a Finnish method, and the precision of its test depends on the formaldehyde content of the sample. Formaldehyde content, mg/kg
The change in formaldehyde content below 20 mg/kg is not noticeable. Precision, %
Note: The calibration curve in the GB/T2912.1 method is different from the curve made using the results mentioned above. 29—absorbance measured in the test sample; A-absorbance measured in the blank reagent,
Aa——absorbance measured in the blank sample (only used in the case of discoloration or staining). Use the corrected absorbance value to find the formaldehyde content through the working curve, expressed in μg/mL. Use formula (2) to calculate the amount of formaldehyde extracted from each sample: F=X100
Where: F-formaldehyde content extracted from the fabric sample, mg/kg; c---formaldehyde content in the extract read from the working curve, mg/L; m-mass of the sample, g.
Calculate the average of the three results.
Test report
The test report shall include the following contents:
a) This standard number
GB/T 2912. 1-1998
b) Sample date, storage method before test and test date; c) Description and packaging method of test sample; d) Total amount of test sample and correction factor; e) Range of working curve;
f) Formaldehyde content extracted from sample, mg/kg; g) Deviation caused by specified procedure.
A1 Total determination
GB/T 2912. 1-1998
(Annex of standard)
Standardization of formaldehyde stock solution
Formaldehyde stock solution with a content of about 1500μg/mL must be accurately standardized in order to make an accurate working curve for colorimetric analysis.
A2 Principle
An aliquot of the stock solution is reacted with an excess of sodium sulfite and back-titrated with a standard acid solution under the indication of thymol acid. A3 Equipment
A3. 110 mL single-marked pipette.
A3. 250 mL single-marked pipette.
A3. 350 mL burette.
A3. 4150 mL conical flask.
A4 Reagents
A4.1 Sodium sulfite [c(NazSO.) = 1 mol/L: Dissolve 126 g of anhydrous sodium sulfite per liter of water (Chapter 4). A4.2 Thymolphthalein indicator: Dissolve 10 g of thymol acid in 1 L of ethanol solution. A4. 3 Sulfuric acid: c(H,SO,) -0. 01 mol/L. Note: It can be purchased from a chemical supply company or calibrated with standard sodium hydroxide solution. Procedure
Pipette 50 mL of sodium sulfite (A4.1) into a conical flask (A3.4), add 2 drops of thymol acid indicator (A4.2), and if necessary, add a few drops of sulfuric acid (A4.3) until the blue color disappears.
Pipette 10 mL of formaldehyde stock solution into the flask (the blue color will reappear), and titrate with sulfuric acid (A4.3) until the blue color disappears, and record the volume of acid used. Note
The volume of sulfuric acid solution is about 25 mL.
2 The pH correction value can be used instead of the thymol acid indicator, in which case the final point is pH = 9.5. The above procedure is repeated once.
A6 Calculation
1 mL 0.01 mol1/L sulfuric acid is equivalent to 0.6 mg formaldehyde. Calculate the formaldehyde concentration in the stock solution using formula (A1): Amount of sulfuric acid (mL) × 0.6 × 1000
Formaldehyde concentration (μg/mL) -
Amount of formaldehyde stock solution (mL)
Calculate the average value of the results, and use the concentration obtained according to formula (A1) to draw a working curve for colorimetric analysis. 28
GB/T2912.1—1998
Appendix B
(Suggestive Appendix)
Method precision references
This standard test method is based on a Finnish method, and the precision of its test depends on the formaldehyde content of the sample. Formaldehyde content, mg/kg
The change in formaldehyde content below 20 mg/kg is not noticeable. Precision, %
Note: The calibration curve in the GB/T2912.1 method is different from the curve made using the results mentioned above. 29
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