GB/T Translated English of Chinese Standard: GB/T NATIONAL STANDARD

Transcription

1 Translated English of Chinese Standard: GB/T ICS W 04 GB NATIONAL STANDARD OF THE PEOPLE S REPUBLIC OF CHINA GB/T Replacing GB/T Textile - Determination of Formaldehyde - Part 1: Free and Hydrolyzed Formaldehyde (Water Extraction Method) 纺织品甲醛的测定第 1 部分 : 游离和水解的甲醛 ( 水萃取法 ) (ISO :1998, MOD) Issued on: June 11, 2006 Implemented on: January 1, 2010 Jointly issued by: General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ); Standardization Administration (SAC) of the People s Republic of China. Page 1 of 17

2 Table of Contents Foreword Scope Normative References Principle Reagents Apparatus Preparation of Formaldehyde Standard Solution and Standard Curve Specimen Preparation Procedures Calculation and Expression of the Results Test Report Appendix A (Normative) Standardization of Formaldehyde Stock Solution Sodium Sulfite Method Appendix B (Normative) Standardization of Formaldehyde Stock Solution Iodometry Appendix C (Informative) Information on Accuracy of the Method Corrigendum: Page 2 of 17

3 Foreword GB/T 2912 "Textile - Determination of formaldehyde" is divided into 3 parts: - Part 1: Free and hydrolyzed formaldehyde (water extraction method); - Part 2: Released formaldehyde (vapor absorption method); - Part 3: High performance liquid chromatography method. This Part is Part 1 of GB/T Adopting re-drafting method, this Part modifies and adopts ISO :1998 "Textile - Determination of formaldehyde - Part 1: Free and hydrolyzed formaldehyde (water extraction method)" (English version). Compared with ISO :1998, the differences of this Part are as follows: - International standards are replaced by Chinese standards for normative references; - Delete the foreword of the international standard; - Add the detailed descriptions in principle; - Add requirements that the calculation results shall be rounded off to integers; - Add Annendix B formaldehyde stock solution calibration method iodometry. This Part replaces GB/T "Textile - Determination of formaldehyde - Part 1: Free and hydrolyzed formaldehyde (water extraction method)". Compared with GB/T , the main changes of this Part are as follows: - Add detection limit in the Scope; - Add GB/T in the Normative References; - Add the detailed descriptions in principle; - Change the specimen s quantity from 3 to 2. Add requirements that the calculation results shall be rounded off to integers; - In Chapter 9, add "If the result is less than 20 mg/kg, test result shall be reported as 'not detectable"; Page 3 of 17

4 Textile - Determination of Formaldehyde- Part 1: Free and Hydrolyzed Formaldehyde (Water Extraction Method) Warning: The personnel using this Part of GB/T 2912 shall have practical experiences in regular laboratory work. This Part does not point out all the possible safety problems. Users have the responsibility to take appropriate safety and health measures and also ensure meeting the conditions specified in relevant regulations of the State. 1 Scope This Part of GB/T 2912 specifies a method for determining the amount of free formaldehyde extracted through water extraction method and partly through hydrolysis. This Part is applicable to the textile samples in any form. This Part is applicable to the textiles with free formaldehyde content between 20mg/kg~3500 mg/kg. The lower limit is 20 mg/kg. Below this limit the result is reported as 'not detectable'. 2 Normative References The following standards contain provisions which, through reference in this Part of GB/T 2912, constitute provisions of this standard. For dated reference, subsequent amendments (excluding correction) or revisions of these publications do not apply. However, the parties who enter into agreement based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards. For undated references, the latest edition of the normative document referred to applies. GB/T 6529 Textiles - Standard atmospheres for conditioning and testing (GB/T , ISO 139:2005, MOD) GB/T 6682 Water for analytical laboratory use - Specification and test methods (GB/T , ISO 3696:1987, MOD) GB/T Laboratory sintered (fritted) filters - Porosity grading, classification Page 5 of 17

5 Appendix B (Normative) Standardization of Formaldehyde Stock Solution Iodometry B.1 General The stock solution containing approximately 1500μg/mL formaldehyde shall be accurately standardized in order to prepare a precise working curve for use in colorimetric analysis. B.2 Principle An aliquot of the stock solution is reacted with an excess of iodine solution. Use standard acid solution, with thymolphthalein as indicator, to carry out the back-titration. B.3 Apparatus B ml, 10 ml, 20 ml, 50 ml one-mark pipette. B ml burette. B ml iodine flask and conical flask with stopper. B ml, 1L volumetric flask. B.4 Reagents B.4.1 Iodine solution [c(i 2 )=0.1 mol/l]: put 13 g of iodine (I 2 ) and 30 g of potassium iodide (KI) into a 1 L brown volumetric flask. Dilute to the mark with water. Shake well and store in the dark place. B.4.2 Sodium hydroxide: c(naoh)=1 mol/l. B.4.3 Sulfuric acid: c(h 2 SO 4 )=0.5 mol/l. B.4.4 Starch indicator: dissolve 0.5g of soluble starch into 100mL water. Boil for 2 min. Prepare it before use. B.4.5 Sodium thiosulfate solution [c(na 2 S 2 O 3 )=0.1 mol/l]: weigh 25 g of Na 2 S 2 O 3 5H 2 O (or 16 g of anhydrous Na 2 S 2 O 3 ). Dissolve it into 1L of water that has been boiled and cooled freshly, and that is added with 0.1g of anhydrous sodium carbonate. Stir to dissolve. Store in a brown bottle. Page 14 of 17

6 c 1 - Concentration of Na 2 S 2 O 3 standard solution, mol/l; Mass of formaldehyde equivalent to 1 ml of Na 2 S 2 O 3 (c= mol/l) standard solution, g; V - Volume of formaldehyde solution used, ml. Calculate the mean of the results and use the concentration determined above in preparing the working curve for the colorimetric analysis. Page 16 of 17

7 Appendix C (Informative) Information on Accuracy of the Method This method is based on a Finnish method for which the accuracy of the test was found to depend on the formaldehyde content of the specimen and to be as follows for uniform samples: Formaldehyde content, mg/kg Accuracy, % Based on above, when contents of formaldehyde is lower than 20 mg/kg, it cannot be shown. Note: the calibration curve in this Part is different from the curve made of above mentioned results. END Corrigendum: GB/T Textile - Determination of Formaldehyde - Part 1: Free and Hydrolyzed Formaldehyde (Water Extraction Method) GB/T Textiles - Determination of Formaldehyde - Part 2: Released Formaldehyde (Vapour Absorption Method) A.4.1 in Appendix A Sodium sulfite [c(na2s2o3)=0.1 mol/l] molecular concentration shall be corrected to be Sodium sulfite [c(na2so3)=1 mol/l]. END of document Page 17 of 17