GB/T 2912.2-1998 Determination of formaldehyde in textiles Part 2: Release of formaldehyde (vapor absorption method)
Some standard content:
GB/T 2912.2—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.
Part 2: Release of formaldehyde (vapor absorption
This standard is equivalent to ISO/FDIS14184-2:1998 & Determination of formaldehyde in textiles)".
GB/T2912.1—1998 provides a method for determining free hydrolyzed formaldehyde by water extraction. This standard has some changes from the original GB/T2912--1982 in terms of the working curve concentration range of formaldehyde standard solution, sample preservation method, use time and dosage of acetylacetone reagent after preparation, test temperature and time, etc. Appendix A of this standard is a standard appendix, and Appendix B and Appendix C are suggestive appendices. 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告誠
National Standard of the People's Republic of China
Textiles-Determination of formaldehyde-Part 2:
Released formaldehyde(Vapour absorption method)
GB/T 2912.2-1998
Replaces GB/T2912-1982
The substances and procedures used in this standard may cause health hazards if appropriate precautions are not taken. This only refers to technical appropriateness, and the user still bears the legal responsibility for health and safety at any stage. Personnel who implement this provision must be qualified and experienced.
1 Specification
This standard specifies the method for determining the amount of formaldehyde released by textiles in any state under accelerated storage conditions by vapor absorption method. This standard is applicable to textiles with formaldehyde release content between 20 mg/kg and 3500 mg/kg. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through 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 in analytical laboratories 3 Principle
A weighed fabric sample is suspended on the water surface in a sealed bottle, and the bottle is placed in a temperature-controlled oven for a specified time. The formaldehyde absorbed by the water is developed with acetylacetone, and the color development solution is used to determine its formaldehyde content by spectrophotometer. 4 Reagents
All reagents are of analytical grade, and all water used is Grade 3 water (GB/T6682-1992). 4.1 Acetylacetone reagent (preparation method see 4.1 of GB/T2912.1-1998). Appendix B describes the use of chromotropic acid to replace acetylacetone reagent. 4.2 Formaldehyde solution, concentration of about 37% (m/V or m/m). 5 Equipment
5.1 Glass (storage) wide-mouth bottle, 1L, with a sealed lid (see Figure 1). Approved by the State Administration of Quality and Technical Supervision on November 26, 1998 and implemented on May 1, 1999
a) Metal mesh basket inserted into a sealed wide-mouth bottle GB/T 2912.2-1998
b) Sample
Unit: mm
2 Basket
3 Wide-mouth bottle
5.2 Small metal mesh basket, as shown in Figure 1a) (or other suitable tools that can hang fabric above the water in the bottle. As an alternative to the metal mesh basket, the fabric folded in half can be tied up with double-stranded sutures and hung on the water surface, with the ends of the thread tied to the top of the bottle cap). 5. 350mL, 250mL, 500mL and 1000mL volumetric flasks. 5. 41mL, 5mL, 10mL, 15mL, 20mL, 25mL, 30mL and 50mL single-mark pipettes. 5.5 Electric heating blower, (49 ± 2) °C. 5.6 Spectrophotometer, wavelength 412 nm.
5.7 10 mL, 50 mL measuring cylinder.
5.8 Test tubes and test tube racks.
5.9 Constant temperature water bath, (40 ± 2) °C. 5.10 Balance, accurate to 0.2 mg.
6 Preparation and calibration of formaldehyde standard solution
6.1 Preparation of formaldehyde stock solution: see 6.1 in GB/T2912.1-1998 6.2 Dilution: see 6.2 in GB/T2912.1-1998. 6.2.1 Preparation of standard solution (S2): see 6.2.1 in GB/T2912.1-1998. 6.2.2 Preparation of calibration solution
Prepare calibration solution according to standard solution (S2). Dilute at least 5 of the following solutions with water in a 500 mL volumetric flask: 1 mL S2 to 500 mL contains 0.15 μg formaldehyde/mL = 7.5 mg formaldehyde/kg fabric 2 mL S2 to 500 mL contains 0.30 μg formaldehyde/mL = 15 mg formaldehyde/kg fabric 5 mL S2 to 500 mL contains 0.75 μg formaldehyde/mL = 37.5 mg formaldehyde/kg fabric 10 mL S2 to 500 mL contains 1.50 μg formaldehyde/mL = 75 mg formaldehyde/kg fabric 15 mL S2 to 500 mL contains 2 .25μg formaldehyde/mL=112.5mg formaldehyde/kg fabric 20ml S2 to 500mL, including 3.00μg formaldehyde/mL=150mg formaldehyde/kg fabric 30ml S2 to 500mL, including 4.50μg formaldehyde/mL=225mg formaldehyde/kg fabric 40ml S2 to 500mL, including 6.00μg formaldehyde/mL=300mg formaldehyde/kg fabric Calculate the working curve y=a+bu, 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.
GB/T 2912.2—1998
Note 1: If the formaldehyde concentration in the calibration solution is to be the same as that in the fabric test solution, double dilution is required. If the fabric contains 20 mg formaldehyde/kg, 1.00 g of sample solution extracted with 50 mL of water contains 20 ug formaldehyde, and so on, the formaldehyde content in 1 mL of test solution is 0.4 μg.
7 Sample preparation
The sample does not need to be humidified, because the dryness and humidity related to humidification can affect the formaldehyde content in the sample. Before testing, store the sample in a container.
Each sample is cut into pieces of about 1 g and then accurately weighed to ±10 mg. Note 2: The sample can be stored in a vinyl bag and wrapped in an aluminum box. The reason is that this can prevent formaldehyde from emitting through the pores of the bag. In addition, if directly in contact, the catalyst and other compounds left on the finished unwashed fabric will react with the aluminum. Note 3: Each sample is tested three times in parallel.
8 Operating Procedure
8.1 Place 50 mL of water at the bottom of each test bottle. Use a wire mesh basket or other means to suspend a sample above the water surface in each bottle. Close the bottle caps and place in an oven at (49 ± 2)°C for 20 h ± 15 min. Remove the test bottle and cool it for (30 ± 5) min. Remove the sample and the mesh basket or other support from the bottle. Close the bottle caps again and shake the bottle to mix any condensate on the side of the bottle. 8.2 Transfer 5 mL of acetylacetone reagent (4.1) to a suitable test tube or other suitable flask, and inject 5 mL of acetylacetone reagent into another test tube for a blank test. Take 5 mL of extract from each sample holding bottle and add it to the test tube. For a blank test, add 5 mL of distilled water to the test tube, mix, shake, place the test tube in a (40 ± 2) ℃ water bath for (30 ± 5) min, cool, measure the absorbance at a wavelength of 412 nm, and use the absorbance to check the formaldehyde content (μg/mL) in the corresponding sample solution on the working curve of the formaldehyde standard solution. 8.3 Same as 8.3. 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 (e.g. 1 hour) in strong sunlight after color development, measures need to be taken to protect the test tube, such as covering the test tube with a cover that does not contain formaldehyde. Otherwise, if the reading needs to be delayed, the color can be stable for a period of time (at least overnight). 9 Calculation and presentation of results
Use formula (1) to calculate the formaldehyde content in the fabric sample. F=× 50
Wherein: F is the formaldehyde content in the fabric sample, mg/kg; c is the formaldehyde content in the extract read from the working curve, mg/L; m is the mass of the sample + g.
10Test report
The test report should include the following contents:
a) This standard number;
b) Sample date, storage method before test and test date; c) Description and packaging method of the test sample; d) Quantity of the test sample;
e) Range of the working curve;
f) Formaldehyde content extracted from the sample, mg/kg; g) Deviations caused by the specified procedure.
A1 General
GB/T 2912.2—1998
Appendix A
(Standard Appendix)
Standardization of Formaldehyde Stock Solution
Formaldehyde stock solution with a content of about 1500ug/mL must be accurately standardized in order to make an accurate working curve for colorimetric analysis.
A2 Principle
The entire amount of stock solution is reacted with excess sodium sulfite and back-titrated with standard acid solution under the indication of thymol acid. A3 Equipment
A3.1 10mL single-standard pipette.
A3.2 50mL single-standard pipette.
A3.3 50mL burette.
A3.4 150mL conical flask.
A4 Reagents
Sodium sulfite (c(NazSO,)=1mol/L): Dissolve 126g of anhydrous sodium sulfite in each liter of water (Chapter 4). A4.1
A4.2 Thymol acid indicator: Dissolve 10g of thymol acid in 1L of ethanol solution. A4.3 Sulfuric acid c(H,SO)=0.01mol/L.
Note: It can be purchased from a chemical supply company or calibrated with standard sodium hydroxide solution. Procedure Library
Pipette 50mL 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 10mL of formaldehyde stock solution into the bottle (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 A calibrated pH 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 mol/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 used (mL) × 0.6 × 1000
Formaldehyde (μg/mL) =
Amount of formaldehyde stock solution used (mL)
Average the calculated results and use the concentrations obtained according to formula (A1) to prepare a working curve for colorimetric analysis. 34
B1 Reagents
GB/T2912.2—1998
Appendix B
(Suggestive Appendix)
Use chromotropic acid instead of acetylacetone reagent to perform the procedure B1.1 Chromotropic acid 50 g/L, freshly prepared aqueous solution, if necessary, filter before use. Note: This reagent is used as the sodium salt of formaldehyde, and its quality varies significantly. A new calibration curve should be made for each new batch of drugs purchased, and the solution should be re-prepared if it exceeds 12 hours.
B1.2 Concentrated sulfuric acid (density 1.84g/L), analytical grade. B1.3 Sulfuric acid [c(H,SO,)=7.5mol/L): Concentrated sulfuric acid (B1.2) (750g, 405mL) is carefully added to water, cooled, diluted to 1 L with water, and cooled before use.
B2 Operation Procedure
B2.1 Pipette a volume of liquid divisible by 1.0 mL (from 8.1) into a test tube. Add 4.0 mL of 7.5 mol/L sulfuric acid (B1.3), 1.0 mL of 50 g/L chromic acid solution (B1.1), and 5.0 mL of concentrated sulfuric acid (B1.2) to the liquid. After adding everything, mix the contents of the test tube thoroughly and wait at least 2 min before adding the next reagent. B2.2 Support the tube and place it vertically in a boiling water bath (the liquid level of the water bath should be higher than the liquid level of the solution in the tube) for (30 ± 1) min. After cooling, transfer the solution to a 50 mL volumetric flask, add distilled water to the mark, shake, and cool the bottle and the contents of the volumetric flask to room temperature for at least 1 h. If necessary, add more water to the mark. B2.3 Use a spectrophotometer or colorimeter to measure the absorbance at 570nm. Place the diluted solution in a 10mm measuring cell and compare it with a blank solution made of 1.0mL water, 4.0mL 7.5mol/L sulfuric acid, 1.0mL 50g/L chromic acid solution and 5.0mL concentrated sulfuric acid. If the absorbance exceeds 1.0, add 0.5mL water to the original liquid that is divisible by 0.5mL and repeat the colorimetric determination. Note
When the formaldehyde concentration is high, the relationship between absorbance and concentration is nonlinear and other colors may appear. Therefore, when the measured absorbance exceeds 1.01
, the operation procedure is repeated after the liquid is diluted with water and the total volume is made up to 1. 0 mL with water. 2 The absorbance does not change within 4 hours after color development.
3 If the absorbance is less than 0.1, the sensitivity of the procedure may be improved by measuring the absorbance before the solution is diluted to 50 mL, provided the solution is allowed to cool to room temperature for at least 1 hour and an appropriate low formaldehyde calibration curve is used. 4 During the dilution of the chromogenic solution, the contents of the volumetric flask should be thoroughly mixed, otherwise the solution will separate and erroneous results will occur. When using this method, two changes may be necessary, one is the amount of formaldehyde standard solution used to prepare the working curve, the other is the amount of sample solution removed from the wide-mouth bottle. Note: Because concentrated sulfuric acid is used when using the chromogenic acid method, great care must be taken to protect all operators and the spectrophotometer. Appendix C
(Informative Appendix)
References for Test Precision
C1 Precision
This method is based on the interlaboratory study (ILS) of American Association of Textile Chemists and Colorists (AATCC) Method 112, i.e., 49°C, 20h extraction time and 5/5 sample to Nessler's reagent ratio. Operators in each laboratory tested each fabric three times. In the first ILS, nine laboratories tested one fabric at three low formaldehyde levels (100μg/g~400μg/g) and analyzed the results by variance. In the second ILS, eight laboratories tested ten 0 ug/g fabrics and analyzed the results.
For the main differences in zero formaldehyde fabrics, see Table C1, and for the main differences in low formaldehyde fabrics, see Table C2. If two or more laboratories are to compare results, the formaldehyde levels of the laboratories should be determined before conducting the test comparison. If the laboratories are comparing the formaldehyde emissions of a single fabric, the major difference in the Single Emission column of Table C2 should be used. If the laboratories are comparing the formaldehyde emissions of a range of fabrics, the major difference in the Diverse Level column of Table C2 should be used.
Major difference zero formaldehyde Mean value limit difference 95% probability (μg/g) Number of tests/mean value
One laboratory
Between laboratories single fabric
Between laboratories multiple fabrics
Major difference low formaldehyde Mean value limit difference 95% probability (μg/g) Table C21
Number of tests/mean value
One laboratory
Laboratory average The number of tests also affects the main difference C2 Tendency
Between laboratories single fabric
Between laboratories multiple fabrics
Formaldehyde release from fabrics can only be defined according to different methods. There is no independent method to determine its true value. In this method, the formaldehyde release content of fabrics under accelerated storage conditions is estimated in this way. There is currently no known tendency. 36
10 Test report
The test report shall include the following contents:
a) This standard number;
b) Sample date, storage method before test and test date;c) Description and packaging method of test sample;d) Quantity of test sample;
e) Range of working curve;
f) Formaldehyde content extracted from sample, mg/kg;g) Deviations caused by specified procedures.
A1 General
GB/T 2912.2—1998
Appendix A
(Standard Appendix)
Standardization of formaldehyde stock solution
Formaldehyde stock solution with a content of about 1500ug/mL must be accurately standardized in order to make an accurate working curve for colorimetric analysis.
A2 Principle
The whole stock solution reacts with excess sodium sulfite and back-titrated with standard acid solution under the indication of thymol acid. A3 Equipment
A3.1 10mL single-label pipette.
A3.2 50mL single-label pipette.
A3.3 50mL burette.
A3.4 150mL conical flask.
A4 Reagents
Sodium sulfite (c(NazSO,)=1mol/L): Dissolve 126g of anhydrous sodium sulfite per liter of water (Chapter 4). A4.1
A4.2 Thymol acid indicator: Dissolve 10g of thymol acid in 1L of ethanol solution. A4.3 Sulfuric acid c(H,SO)=0.01mol/L.
Note: It can be purchased from a chemical supply company or calibrated with standard sodium hydroxide solution. Procedure Library
Pipette 50 mL of sodium sulfite (A4.1) into a conical flask (A3.4) and add 2 drops of thymol acid indicator (A4.2). 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. Record the volume of acid used. Note
The volume of sulfuric acid solution is about 25 mL.
2 A pH calibration value can be used instead of thymol acid indicator. In this case, the final point is pH = 9.5. Repeat the above procedure once.
A6 Calculation
1 mL of 0.01 mol/L sulfuric acid is equivalent to 0.6 mg of formaldehyde. Calculate the formaldehyde concentration in the stock solution using formula (A1): Amount of sulfuric acid (mL) × 0.6 × 1000
Formaldehyde (μg/mL) =
Amount of formaldehyde stock solution (mL)
Calculate the average of the results, and use the concentration obtained according to formula (A1) to prepare the working curve for colorimetric analysis. 34
B1 Reagent
GB/T2912.2—1998
Appendix B
(Suggested Appendix)
Use chromotropic acid instead of acetylacetone reagent to take the procedure B1.1 Chromotropic acid 50 g/L, freshly prepared aqueous solution, if necessary, filter before use. Note: This reagent is used as a sodium salt for the determination of formaldehyde. Its quality varies significantly. A new calibration curve should be made for each new batch of drugs purchased, and the solution should be re-prepared if it exceeds 12 hours.
B1.2 Concentrated sulfuric acid (density 1.84 g/L), analytical grade. B1.3 Sulfuric acid [c(H,SO,) = 7.5 mol/L): Concentrated sulfuric acid (B1.2) (750 g, 405 mL) is carefully added to water, cooled, diluted to 1 L with water, and cooled before use.
B2 Operation procedure
B2.1 Pipette a liquid divisible by 1.0 mL (from 8.1) into a test tube, add 4.0 mL of 7.5 mol/L sulfuric acid (B1.3), 1.0 mL of 50 g/L chromic acid solution (B1.1), and 5.0 mL of concentrated sulfuric acid (B1.2) to this liquid. After adding everything, mix the contents of the test tube thoroughly and wait at least 2 min before adding the next reagent. B2.2 Support the tube so that it is vertically placed in a boiling water bath (the liquid level of the water bath should be above the liquid level of the solution in the tube) for (30 ± 1) min. After cooling, transfer the solution to a 50 mL volumetric flask, add distilled water to the mark, shake, and cool the bottle and the contents of the volumetric flask to room temperature for at least 1 hour. If necessary, add more water to the mark. B2.3 Using a spectrophotometer or colorimeter, measure the absorbance at 570 nm and place the diluted solution in a 10 mm measuring cell against a blank solution made of 1.0 mL of water, 4.0 mL of 7.5 mol/L sulfuric acid, 1.0 mL of 50 g/L chromic acid solution, and 5.0 mL of concentrated sulfuric acid. If the absorbance exceeds 1.0, add 0.5 mL of water to the original solution that is divisible by 0.5 mL and repeat the colorimetric determination. NOTE
At high formaldehyde concentrations, the relationship between absorbance and concentration is nonlinear and other colors may also appear. Therefore, when measuring absorbance above 1.01
, the procedure is repeated after dilution with water and the total volume is made up to 1.0 mL with water. 2 The absorbance does not change within 4 hours after color development.
3 If the absorbance is less than 0.1, the sensitivity of the procedure can be improved by measuring the absorbance before the solution is diluted to 50 mL. Provided that the solution is allowed to cool to room temperature for at least 1 hour, an appropriate low formaldehyde calibration curve is used. 4 During the dilution of the color development solution, the contents of the volumetric flask should be thoroughly mixed, otherwise the solution will separate and erroneous results will occur. When using this method, two changes may be necessary, one is the amount of formaldehyde standard solution used to prepare the working curve, and the other is the amount of sample solution removed from the wide-mouth bottle. NOTE: Because concentrated sulfuric acid is used when using the chromotropic acid method, great care must be taken to protect all operators and the spectrophotometer. Appendix C
(Informative Appendix)
References for Test Precision
C1 Precision
This method is based on the interlaboratory study (ILS) of American Association of Textile Chemists and Colorists (AATCC) Method 112, i.e., 49°C, 20h extraction time and 5/5 sample to Nessler's reagent ratio. Operators in each laboratory tested each fabric three times. In the first ILS, nine laboratories tested one fabric at three low formaldehyde levels (100μg/g~400μg/g) and analyzed the results by variance. In the second ILS, eight laboratories tested ten 0 ug/g fabrics and analyzed the results.
For the main differences in zero formaldehyde fabrics, see Table C1, and for the main differences in low formaldehyde fabrics, see Table C2. If two or more laboratories are to compare results, the formaldehyde levels of the laboratories should be determined before conducting the test comparison. If the laboratories are comparing the formaldehyde emissions of a single fabric, the major difference in the Single Emission column of Table C2 should be used. If the laboratories are comparing the formaldehyde emissions of a range of fabrics, the major difference in the Diverse Level column of Table C2 should be used.
Major difference zero formaldehyde Mean value limit difference 95% probability (μg/g) Number of tests/mean value
One laboratory
Between laboratories single fabric
Between laboratories multiple fabrics
Major difference low formaldehyde Mean value limit difference 95% probability (μg/g) Table C21
Number of tests/mean value
One laboratory
Laboratory average The number of tests also affects the main difference C2 Tendency
Between laboratories single fabric
Between laboratories multiple fabrics
Formaldehyde release from fabrics can only be defined according to different methods. There is no independent method to determine its true value. In this method, the formaldehyde release content of fabrics under accelerated storage conditions is estimated in this way. There is currently no known tendency. 36
10 Test report
The test report shall include the following contents:
a) This standard number;
b) Sample date, storage method before test and test date;c) Description and packaging method of test sample;d) Quantity of test sample;
e) Range of working curve;
f) Formaldehyde content extracted from sample, mg/kg;g) Deviations caused by specified procedures.
A1 General
GB/T 2912.2—1998
Appendix A
(Standard Appendix)
Standardization of formaldehyde stock solution
Formaldehyde stock solution with a content of about 1500ug/mL must be accurately standardized in order to make an accurate working curve for colorimetric analysis.
A2 Principle
The whole stock solution reacts with excess sodium sulfite and back-titrated with standard acid solution under the indication of thymol acid. A3 Equipment
A3.1 10mL single-label pipette.
A3.2 50mL single-label pipette.
A3.3 50mL burette.
A3.4 150mL conical flask.
A4 Reagents
Sodium sulfite (c(NazSO,)=1mol/L): Dissolve 126g of anhydrous sodium sulfite per liter of water (Chapter 4). A4.1
A4.2 Thymol acid indicator: Dissolve 10g of thymol acid in 1L of ethanol solution. A4.3 Sulfuric acid c(H,SO)=0.01mol/L.
Note: It can be purchased from a chemical supply company or calibrated with standard sodium hydroxide solution. Procedure Library
Pipette 50 mL of sodium sulfite (A4.1) into a conical flask (A3.4) and add 2 drops of thymol acid indicator (A4.2). 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. Record the volume of acid used. Note
The volume of sulfuric acid solution is about 25 mL.
2 A pH calibration value can be used instead of thymol acid indicator. In this case, the final point is pH = 9.5. Repeat the above procedure once.
A6 Calculation
1 mL of 0.01 mol/L sulfuric acid is equivalent to 0.6 mg of formaldehyde. Calculate the formaldehyde concentration in the stock solution using formula (A1): Amount of sulfuric acid (mL) × 0.6 × 1000
Formaldehyde (μg/mL) =
Amount of formaldehyde stock solution (mL)
Calculate the average of the results, and use the concentration obtained according to formula (A1) to prepare the working curve for colorimetric analysis. 34
B1 Reagent
GB/T2912.2—1998
Appendix B
(Suggested Appendix)
Use chromotropic acid instead of acetylacetone reagent to take the procedure B1.1 Chromotropic acid 50 g/L, freshly prepared aqueous solution, if necessary, filter before use. Note: This reagent is used as a sodium salt for the determination of formaldehyde. Its quality varies significantly. A new calibration curve should be made for each new batch of drugs purchased, and the solution should be re-prepared if it exceeds 12 hours.
B1.2 Concentrated sulfuric acid (density 1.84 g/L), analytical grade. B1.3 Sulfuric acid [c(H,SO,) = 7.5 mol/L): Concentrated sulfuric acid (B1.2) (750 g, 405 mL) is carefully added to water, cooled, diluted to 1 L with water, and cooled before use.
B2 Operation procedure
B2.1 Pipette a liquid divisible by 1.0 mL (from 8.1) into a test tube, add 4.0 mL of 7.5 mol/L sulfuric acid (B1.3), 1.0 mL of 50 g/L chromic acid solution (B1.1), and 5.0 mL of concentrated sulfuric acid (B1.2) to this liquid. After adding everything, mix the contents of the test tube thoroughly and wait at least 2 min before adding the next reagent. B2.2 Support the tube so that it is vertically placed in a boiling water bath (the liquid level of the water bath should be above the liquid level of the solution in the tube) for (30 ± 1) min. After cooling, transfer the solution to a 50 mL volumetric flask, add distilled water to the mark, shake, and cool the bottle and the contents of the volumetric flask to room temperature for at least 1 hour. If necessary, add more water to the mark. B2.3 Using a spectrophotometer or colorimeter, measure the absorbance at 570 nm and place the diluted solution in a 10 mm measuring cell against a blank solution made of 1.0 mL of water, 4.0 mL of 7.5 mol/L sulfuric acid, 1.0 mL of 50 g/L chromic acid solution, and 5.0 mL of concentrated sulfuric acid. If the absorbance exceeds 1.0, add 0.5 mL of water to the original solution that is divisible by 0.5 mL and repeat the colorimetric determination. NOTE
At high formaldehyde concentrations, the relationship between absorbance and concentration is nonlinear and other colors may also appear. Therefore, when measuring absorbance above 1.01
, the procedure is repeated after dilution with water and the total volume is made up to 1.0 mL with water. 2 The absorbance does not change within 4 hours after color development.
3 If the absorbance is less than 0.1, the sensitivity of the procedure can be improved by measuring the absorbance before the solution is diluted to 50 mL. Provided that the solution is allowed to cool to room temperature for at least 1 hour, an appropriate low formaldehyde calibration curve is used. 4 During the dilution of the color development solution, the contents of the volumetric flask should be thoroughly mixed, otherwise the solution will separate and erroneous results will occur. When using this method, two changes may be necessary, one is the amount of formaldehyde standard solution used to prepare the working curve, and the other is the amount of sample solution removed from the wide-mouth bottle. NOTE: Because concentrated sulfuric acid is used when using the chromotropic acid method, great care must be taken to protect all operators and the spectrophotometer. Appendix C
(Informative Appendix)
References for Test Precision
C1 Precision
This method is based on the interlaboratory study (ILS) of American Association of Textile Chemists and Colorists (AATCC) Method 112, i.e., 49°C, 20h extraction time and 5/5 sample to Nessler's reagent ratio. Operators in each laboratory tested each fabric three times. In the first ILS, nine laboratories tested one fabric at three low formaldehyde levels (100μg/g~400μg/g) and analyzed the results by variance. In the second ILS, eight laboratories tested ten 0 ug/g fabrics and analyzed the results.
For the main differences in zero formaldehyde fabrics, see Table C1, and for the main differences in low formaldehyde fabrics, see Table C2. If two or more laboratories are to compare results, the formaldehyde levels of the laboratories should be determined before conducting the test comparison. If the laboratories are comparing the formaldehyde emissions of a single fabric, the major difference in the Single Emission column of Table C2 should be used. If the laboratories are comparing the formaldehyde emissions of a range of fabrics, the major difference in the Diverse Level column of Table C2 should be used.
Major difference zero formaldehyde Mean value limit difference 95% probability (μg/g) Number of tests/mean value
One laboratory
Between laboratories single fabric
Between laboratories multiple fabrics
Major difference low formaldehyde Mean value limit difference 95% probability (μg/g) Table C21
Number of tests/mean value
One laboratory
Laboratory average The number of tests also affects the main difference C2 Tendency
Between laboratories single fabric
Between laboratories multiple fabrics
Formaldehyde release from fabrics can only be defined according to different methods. There is no independent method to determine its true value. In this method, the formaldehyde release content of fabrics under accelerated storage conditions is estimated in this way. There is currently no known tendency. 36250mL single-standard pipette.
A3.350mL burette.
A3.4150mL conical flask.
A4 Reagents
Sodium sulfite (c(NazSO,)=1mol/L): Dissolve 126g of anhydrous sodium sulfite per liter of water (Chapter 4). A4.1
A4.2 Thymol acid indicator: Dissolve 10g of thymol acid in 1L of ethanol solution. A4.3 Sulfuric acid c(H,SO)=0.01mol/L.
Note: It can be purchased from a chemical supply company or calibrated with standard sodium hydroxide solution. Procedure Library
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 A pH correction value can be used instead of thymol acid indicator, in which case the final point is pH = 9.5. Repeat the above procedure once.
A6 Calculation
1 mL of 0.01 mol/L sulfuric acid is equivalent to 0.6 mg of formaldehyde. Calculate the formaldehyde concentration in the stock solution using formula (A1): Amount of sulfuric acid (mL) × 0.6 × 1000
Formaldehyde (μg/mL) =
Amount of formaldehyde stock solution (mL)
Calculate the average of the results, and use the concentration obtained according to formula (A1) to prepare the working curve for colorimetric analysis. 34
B1 Reagent
GB/T2912.2—1998
Appendix B
(Suggested Appendix)
Use chromotropic acid instead of acetylacetone reagent to take the procedure B1.1 Chromotropic acid 50 g/L, freshly prepared aqueous solution, if necessary, filter before use. Note: This reagent is used as a sodium salt for the determination of formaldehyde. Its quality varies significantly. A new calibration curve should be made for each new batch of drugs purchased, and the solution should be re-prepared if it exceeds 12 hours.
B1.2 Concentrated sulfuric acid (density 1.84 g/L), analytical grade. B1.3 Sulfuric acid [c(H,SO,) = 7.5 mol/L): Concentrated sulfuric acid (B1.2) (750 g, 405 mL) is carefully added to water, cooled, diluted to 1 L with water, and cooled before use.
B2 Operation procedure
B2.1 Pipette a liquid divisible by 1.0 mL (from 8.1) into a test tube, add 4.0 mL of 7.5 mol/L sulfuric acid (B1.3), 1.0 mL of 50 g/L chromic acid solution (B1.1), and 5.0 mL of concentrated sulfuric acid (B1.2) to this liquid. After adding everything, mix the contents of the test tube thoroughly and wait at least 2 min before adding the next reagent. B2.2 Support the tube so that it is vertically placed in a boiling water bath (the liquid level of the water bath should be above the liquid level of the solution in the tube) for (30 ± 1) min. After cooling, transfer the solution to a 50 mL volumetric flask, add distilled water to the mark, shake, and cool the bottle and the contents of the volumetric flask to room temperature for at least 1 hour. If necessary, add more water to the mark. B2.3 Using a spectrophotometer or colorimeter, measure the absorbance at 570 nm and place the diluted solution in a 10 mm measuring cell against a blank solution made of 1.0 mL of water, 4.0 mL of 7.5 mol/L sulfuric acid, 1.0 mL of 50 g/L chromic acid solution, and 5.0 mL of concentrated sulfuric acid. If the absorbance exceeds 1.0, add 0.5 mL of water to the original solution that is divisible by 0.5 mL and repeat the colorimetric determination. NOTE
At high formaldehyde concentrations, the relationship between absorbance and concentration is nonlinear and other colors may also appear. Therefore, when measuring absorbance above 1.01
, the procedure is repeated after dilution with water and the total volume is made up to 1.0 mL with water. 2 The absorbance does not change within 4 hours after color development.
3 If the absorbance is less than 0.1, the sensitivity of the procedure can be improved by measuring the absorbance before the solution is diluted to 50 mL. Provided that the solution is allowed to cool to room temperature for at least 1 hour, an appropriate low formaldehyde calibration curve is used. 4 During the dilution of the color development solution, the contents of the volumetric flask should be thoroughly mixed, otherwise the solution will separate and erroneous results will occur. When using this method, two changes may be necessary, one is the amount of formaldehyde standard solution used to prepare the working curve, and the other is the amount of sample solution removed from the wide-mouth bottle. NOTE: Because concentrated sulfuric acid is used when using the chromotropic acid method, great care must be taken to protect all operators and the spectrophotometer. Appendix C
(Informative Appendix)
References for Test Precision
C1 Precision
This method is based on the interlaboratory study (ILS) of American Association of Textile Chemists and Colorists (AATCC) Method 112, i.e., 49°C, 20h extraction time and 5/5 sample to Nessler's reagent ratio. Operators in each laboratory tested each fabric three times. In the first ILS, nine laboratories tested one fabric at three low formaldehyde levels (100μg/g~400μg/g) and analyzed the results by variance. In the second ILS, eight laboratories tested ten 0 ug/g fabrics and analyzed the results.
For the main differences in zero formaldehyde fabrics, see Table C1, and for the main differences in low formaldehyde fabrics, see Table C2. If two or more laboratories are to compare results, the formaldehyde levels of the laboratories should be determined before conducting the test comparison. If the laboratories are comparing the formaldehyde emissions of a single fabric, the major difference in the Single Emission column of Table C2 should be used. If the laboratories are comparing the formaldehyde emissions of a range of fabrics, the major difference in the Diverse Level column of Table C2 should be used.
Major difference zero formaldehyde Mean value limit difference 95% probability (μg/g) Number of tests/mean value
One laboratory
Between laboratories single fabric
Between laboratories multiple fabrics
Major difference low formaldehyde Mean value limit difference 95% probability (μg/g) Table C21
Number of tests/mean value
One laboratory
Laboratory average The number of tests also affects the main difference C2 Tendency
Between laboratories single fabric
Between laboratories multiple fabrics
Formaldehyde release from fabrics can only be defined according to different methods. There is no independent method to determine its true value. In this method, the formaldehyde release content of fabrics under accelerated storage conditions is estimated in this way. There is currently no known tendency. 36250mL single-standard pipette.
A3.350mL burette.
A3.4150mL conical flask.
A4 Reagents
Sodium sulfite (c(NazSO,)=1mol/L): Dissolve 126g of anhydrous sodium sulfite per liter of water (Chapter 4). A4.1
A4.2 Thymol acid indicator: Dissolve 10g of thymol acid in 1L of ethanol solution. A4.3 Sulfuric acid c(H,SO)=0.01mol/L.
Note: It can be purchased from a chemical supply company or calibrated with standard sodium hydroxide solution. Procedure Library
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 A pH correction value can be used instead of thymol acid indicator, in which case the final point is pH = 9.5. Repeat the above procedure once.
A6 Calculation
1 mL of 0.01 mol/L sulfuric acid is equivalent to 0.6 mg of formaldehyde. Calculate the formaldehyde concentration in the stock solution using formula (A1): Amount of sulfuric acid (mL) × 0.6 × 1000
Formaldehyde (μg/mL) =
Amount of formaldehyde stock solution (mL)
Calculate the average of the results, and use the concentration obtained according to formula (A1) to prepare the working curve for colorimetric analysis. 34
B1 Reagent
GB/T2912.2—1998
Appendix B
(Suggested Appendix)
Use chromotropic acid instead of acetylacetone reagent to take the procedure B1.1 Chromotropic acid 50 g/L, freshly prepared aqueous solution, if necessary, filter before use. Note: This reagent is used as a sodium salt for the determination of formaldehyde. Its quality varies significantly. A new calibration curve should be made for each new batch of drugs purchased, and the solution should be re-prepared if it exceeds 12 hours.
B1.2 Concentrated sulfuric acid (density 1.84 g/L), analytical grade. B1.3 Sulfuric acid [c(H,SO,) = 7.5 mol/L): Concentrated sulfuric acid (B1.2) (750 g, 405 mL) is carefully added to water, cooled, diluted to 1 L with water, and cooled before use.
B2 Operation procedure
B2.1 Pipette a liquid divisible by 1.0 mL (from 8.1) into a test tube, add 4.0 mL of 7.5 mol/L sulfuric acid (B1.3), 1.0 mL of 50 g/L chromic acid solution (B1.1), and 5.0 mL of concentrated sulfuric acid (B1.2) to this liquid. After adding everything, mix the contents of the test tube thoroughly and wait at least 2 min before adding the next reagent. B2.2 Support the tube so that it is vertically placed in a boiling water bath (the liquid level of the water bath should be above the liquid level of the solution in the tube) for (30 ± 1) min. After cooling, transfer the solution to a 50 mL volumetric flask, add distilled water to the mark, shake, and cool the bottle and the contents of the volumetric flask to room temperature for at least 1 hour. If necessary, add more water to the mark. B2.3 Using a spectrophotometer or colorimeter, measure the absorbance at 570 nm and place the diluted solution in a 10 mm measuring cell against a blank solution made of 1.0 mL of water, 4.0 mL of 7.5 mol/L sulfuric acid, 1.0 mL of 50 g/L chromic acid solution, and 5.0 mL of concentrated sulfuric acid. If the absorbance exceeds 1.0, add 0.5 mL of water to the original solution that is divisible by 0.5 mL and repeat the colorimetric determination. NOTE
At high formaldehyde concentrations, the relationship between absorbance and concentration is nonlinear and other colors may also appear. Therefore, when measuring absorbance above 1.01
, the procedure is repeated after dilution with water and the total volume is made up to 1.0 mL with water. 2 The absorbance does not change within 4 hours after color development.
3 If the absorbance is less than 0.1, the sensitivity of the procedure can be improved by measuring the absorbance before the solution is diluted to 50 mL. Provided that the solution is allowed to cool to room temperature for at least 1 hour, an appropriate low formaldehyde calibration curve is used. 4 During the dilution of the color development solution, the contents of the volumetric flask should be thoroughly mixed, otherwise the solution will separate and erroneous results will occur. When using this method, two changes may be necessary, one is the amount of formaldehyde standard solution used to prepare the working curve, and the other is the amount of sample solution removed from the wide-mouth bottle. NOTE: Because concentrated sulfuric acid is used when using the chromotropic acid method, great care must be taken to protect all operators and the spectrophotometer. Appendix C
(Informative Appendix)
References for Test Precision
C1 Precision
This method is based on the interlaboratory study (ILS) of American Association of Textile Chemists and Colorists (AATCC) Method 112, i.e., 49°C, 20h extraction time and 5/5 sample to Nessler's reagent ratio. Operators in each laboratory tested each fabric three times. In the first ILS, nine laboratories tested one fabric at three low formaldehyde levels (100μg/g~400μg/g) and analyzed the results by variance. In the second ILS, eight laboratories tested ten 0 ug/g fabrics and analyzed the results.
For the main differences in zero formaldehyde fabrics, see Table C1, and for the main differences in low formaldehyde fabrics, see Table C2. If two or more laboratories are to compare results, the formaldehyde levels of the laboratories should be determined before conducting the test comparison. If the laboratories are comparing the formaldehyde emissions of a single fabric, the major difference in the Single Emission column of Table C2 should be used. If the laboratories are comparing the formaldehyde emissions of a range of fabrics, the major difference in the Diverse Level column of Table C2 should be used.
Major difference zero formaldehyde Mean value limit difference 95% probability (μg/g) Number of tests/mean value
One laboratory
Between laboratories single fabric
Between laboratories multiple fabrics
Major difference low formaldehyde Mean value limit difference 95% probability (μg/g) Table C21
Number of tests/mean value
One laboratory
Laboratory average The number of tests also affects the main difference C2 Tendency
Between laboratories single fabric
Between laboratories multiple fabrics
Formaldehyde release from fabrics can only be defined according to different methods. There is no independent method to determine its true value. In this method, the formaldehyde release content of fabrics under accelerated storage conditions is estimated in this way. There is currently no known tendency. 36Filter before use. Note: This reagent is used to determine the sodium salt of formaldehyde. Its quality varies significantly. A new calibration curve should be made for each new batch of drugs purchased. The solution should be re-prepared if it exceeds 12 hours.
B1.2 Concentrated sulfuric acid (density 1.84g/L), analytical grade. B1.3 Sulfuric acid [c(H,SO,)=7.5mol/L): Concentrated sulfuric acid (B1.2) (750g, 405mL) is carefully added to water, cooled, diluted with water to 1 L, and cooled before use.
B2 Operation Procedure
B2.1 Pipette a volume of liquid divisible by 1.0 mL (from 8.1) into a test tube. Add 4.0 mL of 7.5 mol/L sulfuric acid (B1.3), 1.0 mL of 50 g/L chromic acid solution (B1.1), and 5.0 mL of concentrated sulfuric acid (B1.2) to the liquid. After adding everything, mix the contents of the test tube thoroughly and wait at least 2 min before adding the next reagent. B2.2 Support the tube and place it vertically in a boiling water bath (the liquid level of the water bath should be higher than the liquid level of the solution in the tube) for (30 ± 1) min. After cooling, transfer the solution to a 50 mL volumetric flask, add distilled water to the mark, shake, and cool the bottle and the contents of the volumetric flask to room temperature for at least 1 h. If necessary, add more water to the mark. B2.3 Use a spectrophotometer or colorimeter to measure the absorbance at 570nm. Place the diluted solution in a 10mm measuring cell and compare it with a blank solution made of 1.0mL water, 4.0mL 7.5mol/L sulfuric acid, 1.0mL 50g/L chromic acid solution and 5.0mL concentrated sulfuric acid. If the absorbance exceeds 1.0, add 0.5mL water to the original liquid that is divisible by 0.5mL and repeat the colorimetric determination. Note
When the formaldehyde concentration is high, the relationship between absorbance and concentration is nonlinear and other colors may appear. Therefore, when the measured absorbance exceeds 1.01
, the operation procedure is repeated after the liquid is diluted with water and the total volume is made up to 1. 0 mL with water. 2 The absorbance does not change within 4 hours after color development.
3 If the absorbance is less than 0.1, the sensitivity of the procedure may be improved by measuring the absorbance before the solution is diluted to 50 mL, provided the solution is allowed to cool to room temperature for at least 1 hour and an appropriate low formaldehyde calibration curve is used. 4 During the dilution of the chromogenic solution, the contents of the volumetric flask should be thoroughly mixed, otherwise the solution will separate and erroneous results will occur. When using this method, two changes may be necessary, one is the amount of formaldehyde standard solution used to prepare the working curve, the other is the amount of sample solution removed from the wide-mouth bottle. Note: Because concentrated sulfuric acid is used when using the chromogenic acid method, great care must be taken to protect all operators and the spectrophotometer. Appendix C
(Informative Appendix)
References for Test Precision
C1 Precision
This method is based on the interlaboratory study (ILS) of American Association of Textile Chemists and Colorists (AATCC) Method 112, i.e., 49°C, 20h extraction time and 5/5 sample to Nessler's reagent ratio. Operators in each laboratory tested each fabric three times. In the first ILS, nine laboratories tested one fabric at three low formaldehyde levels (100μg/g~400μg/g) and analyzed the results by variance. In the second ILS, eight laboratories tested ten 0 ug/g fabrics and analyzed the results.
For the main differences in zero formaldehyde fabrics, see Table C1, and for the main differences in low formaldehyde fabrics, see Table C2. If two or more laboratories are to compare results, the formaldehyde levels of the laboratories should be determined before conducting the test comparison. If the laboratories are comparing the formaldehyde emissions of a single fabric, the major difference in the Single Emission column of Table C2 should be used. If the laboratories are comparing the formaldehyde emissions of a range of fabrics, the major difference in the Diverse Level column of Table C2 should be used.
Major difference zero formaldehyde Mean value limit difference 95% probability (μg/g) Number of tests/mean value
One laboratory
Between laboratories single fabric
Between laboratories multiple fabrics
Major difference low formaldehyde Mean value limit difference 95% probability (μg/g) Table C21
Number of tests/mean value
One laboratory
Laboratory average The number of tests also affects the main difference C2 TendencybzxZ.net
Between laboratories single fabric
Between laboratories multiple fabrics
Formaldehyde release from fabrics can only be defined according to different methods. There is no independent method to determine its true value. In this method, the formaldehyde release content of fabrics under accelerated storage conditions is estimated in this way. There is currently no known tendency. 36Filter before use. Note: This reagent is used to determine the sodium salt of formaldehyde. Its quality varies significantly. A new calibration curve should be made for each new batch of drugs purchased. The solution should be re-prepared if it exceeds 12 hours.
B1.2 Concentrated sulfuric acid (density 1.84g/L), analytical grade. B1.3 Sulfuric acid [c(H,SO,)=7.5mol/L): Concentrated sulfuric acid (B1.2) (750g, 405mL) is carefully added to water, cooled, diluted with water to 1 L, and cooled before use.
B2 Operation Procedure
B2.1 Pipette a volume of liquid divisible by 1.0 mL (from 8.1) into a test tube. Add 4.0 mL of 7.5 mol/L sulfuric acid (B1.3), 1.0 mL of 50 g/L chromic acid solution (B1.1), and 5.0 mL of concentrated sulfuric acid (B1.2) to the liquid. After adding everything, mix the contents of the test tube thoroughly and wait at least 2 min before adding the next reagent. B2.2 Support the tube and place it vertically in a boiling water bath (the liquid level of the water bath should be higher than the liquid level of the solution in the tube) for (30 ± 1) min. After cooling, transfer the solution to a 50 mL volumetric flask, add distilled water to the mark, shake, and cool the bottle and the contents of the volumetric flask to room temperature for at least 1 h. If necessary, add more water to the mark. B2.3 Use a spectrophotometer or colorimeter to measure the absorbance at 570nm. Place the diluted solution in a 10mm measuring cell and compare it with a blank solution made of 1.0mL water, 4.0mL 7.5mol/L sulfuric acid, 1.0mL 50g/L chromic acid solution and 5.0mL concentrated sulfuric acid. If the absorbance exceeds 1.0, add 0.5mL water to the original liquid that is divisible by 0.5mL and repeat the colorimetric determination. Note
When the formaldehyde concentration is high, the relationship between absorbance and concentration is nonlinear and other colors may appear. Therefore, when the measured absorbance exceeds 1.01
, the operation procedure is repeated after the liquid is diluted with water and the total volume is made up to 1. 0 mL with water. 2 The absorbance does not change within 4 hours after color development.
3 If the absorbance is less than 0.1, the sensitivity of the procedure may be improved by measuring the absorbance before the solution is diluted to 50 mL, provided the solution is allowed to cool to room temperature for at least 1 hour and an appropriate low formaldehyde calibration curve is used. 4 During the dilution of the chromogenic solution, the contents of the volumetric flask should be thoroughly mixed, otherwise the solution will separate and erroneous results will occur. When using this method, two changes may be necessary, one is the amount of formaldehyde standard solution used to prepare the working curve, the other is the amount of sample solution removed from the wide-mouth bottle. Note: Because concentrated sulfuric acid is used when using the chromogenic acid method, great care must be taken to protect all operators and the spectrophotometer. Appendix C
(Informative Appendix)
References for Test Precision
C1 Precision
This method is based on the interlaboratory study (ILS) of American Association of Textile Chemists and Colorists (AATCC) Method 112, i.e., 49°C, 20h extraction time and 5/5 sample to Nessler's reagent ratio. Operators in each laboratory tested each fabric three times. In the first ILS, nine laboratories tested one fabric at three low formaldehyde levels (100μg/g~400μg/g) and analyzed the results by variance. In the second ILS, eight laboratories tested ten 0 ug/g fabrics and analyzed the results.
For the main differences in zero formaldehyde fabrics, see Table C1, and for the main differences in low formaldehyde fabrics, see Table C2. If two or more laboratories are to compare results, the formaldehyde levels of the laboratories should be determined before conducting the test comparison. If the laboratories are comparing the formaldehyde emissions of a single fabric, the major difference in the Single Emission column of Table C2 should be used. If the laboratories are comparing the formaldehyde emissions of a range of fabrics, the major difference in the Diverse Level column of Table C2 should be used.
Major difference zero formaldehyde Mean value limit difference 95% probability (μg/g) Number of tests/mean value
One laboratory
Between laboratories single fabric
Between laboratories multiple fabrics
Major difference low formaldehyde Mean value limit difference 95% probability (μg/g) Table C21
Number of tests/mean value
One laboratory
Laboratory average The number of tests also affects the main difference C2 Tendency
Between laboratories single fabric
Between laboratories multiple fabrics
Formaldehyde release from fabrics can only be defined according to different methods. There is no independent method to determine its true value. In this method, the formaldehyde release content of fabrics under accelerated storage conditions is estimated in this way. There is currently no known tendency. 36The results were analyzed by variance method. In the second ILS, eight laboratories tested ten 0 ug/g fabrics and analyzed the results.
The main differences for zero formaldehyde fabrics are detailed in Table C1, and the main differences for low formaldehyde fabrics are detailed in Table C2. If two or more laboratories want to compare results, the formaldehyde levels of the laboratories should be determined before conducting the test comparison. If the laboratory comparison is about the formaldehyde emission of a single fabric, the main difference in the single emission column in Table C2 should be used. If the laboratory comparison is about the formaldehyde emission range of a series of fabrics, the main difference in the diversified level column in Table C2 should be used.
Major difference zero formaldehyde Mean value limit difference 95% probability (μg/g) Number of tests/mean value
One laboratory
Between laboratories single fabric
Between laboratories multiple fabrics
Major difference low formaldehyde Mean value limit difference 95% probability (μg/g) Table C21
Number of tests/mean value
One laboratory
Laboratory average The number of tests also affects the main difference C2 Tendency
Between laboratories single fabric
Between laboratories multiple fabrics
Formaldehyde release from fabrics can only be defined according to different methods. There is no independent method to determine its true value. In this method, the formaldehyde release content of fabrics under accelerated storage conditions is estimated in this way. There is currently no known tendency. 36The results were analyzed by variance method. In the second ILS, eight laboratories tested ten 0 ug/g fabrics and analyzed the results.
The main differences for zero formaldehyde fabrics are detailed in Table C1, and the main differences for low formaldehyde fabrics are detailed in Table C2. If two or more laboratories want to compare results, the formaldehyde levels of the laboratories should be determined before conducting the test comparison. If the laboratory comparison is about the formaldehyde emission of a single fabric, the main difference in the single emission column in Table C2 should be used. If the laboratory comparison is about the formaldehyde emission range of a series of fabrics, the main difference in the diversified level column in Table C2 should be used.
Major difference zero formaldehyde Mean value limit difference 95% probability (μg/g) Number of tests/mean value
One laboratory
Between laboratories single fabric
Between laboratories multiple fabrics
Major difference low formaldehyde Mean value limit difference 95% probability (μg/g) Table C21
Number of tests/mean value
One laboratory
Laboratory average The number of tests also affects the main difference C2 Tendency
Between laboratories single fabric
Between laboratories multiple fabrics
Formaldehyde release from fabrics can only be defined according to different methods. There is no independent method to determine its true value. In this method, the formaldehyde release content of fabrics under accelerated storage conditions is estimated in this way. There is currently no known tendency. 36
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