HOME   Cart(0)   Quotation   About-Us Tax PDFs Standard-List Powered by Google www.ChineseStandard.net Database: 189759 (2 Feb 2025)

GB 21027-2020 English PDF (GB 21027-2007)

GB 21027-2020_English: PDF (GB21027-2020)
Standard IDContents [version]USDSTEP2[PDF] delivered inStandard Title (Description)StatusPDF
GB 21027-2020English305 Add to Cart 0--9 seconds. Auto-delivery Request in common use of security for student’s articles Valid GB 21027-2020
GB 21027-2007English85 Add to Cart 0--9 seconds. Auto-delivery Request in common use of security for student′s articles Obsolete GB 21027-2007


BASIC DATA
Standard ID GB 21027-2020 (GB21027-2020)
Description (Translated English) Request in common use of security for student��s articles
Sector / Industry National Standard
Classification of Chinese Standard Y50
Classification of International Standard 97.180
Word Count Estimation 22,272
Date of Issue 2020-07-23
Date of Implementation 2022-02-01
Older Standard (superseded by this standard) GB 21027-2007
Administrative Organization Ministry of Industry and Information Technology of the People's Republic of China
Proposing organization Ministry of Industry and Information Technology of the People's Republic of China
Issuing agency(ies) State Administration for Market Regulation, National Standardization Administration

BASIC DATA
Standard ID GB 21027-2007 (GB21027-2007)
Description (Translated English) Request in common use of security for student��s articles
Sector / Industry National Standard
Classification of Chinese Standard Y50
Classification of International Standard 97.180
Word Count Estimation 15,189
Date of Issue 2007-06-07
Date of Implementation 2008-04-01
Quoted Standard GB/T 601-2002; GB/T 606-2003; GB/T 2793-1995; GB/T 2912.1-1998; GB 5296.5-2006; GB 6675-2003; GB/T 7974-2002; GB/T 9722 - 2006; GB/T 13354-1992; GB 19601-2004
Drafting Organization Shanghai SIIC Marie Painting Materials Co., Ltd.
Administrative Organization National Standardization Center stationery
Regulation (derived from) Chinese National Standards Bulletin 2007 No. 7 (No. 107 overall)- GB Commission
Proposing organization China Light Industry Federation
Issuing agency(ies) General Administration of Quality Supervision, Inspection and Quarantine of PRC, China National Standardization Administration Committee
Summary This Chinese standard specifies the safety requirements for school supplies, test methods, inspection rules, marking and instructions for use. This standard applies to minor students used watercolor paints, crayons, pencils, finger paints, modeling clay, eraser, altered products (correction fluid, correction tape, correction pen), adhesives, watercolor pen, writing pen, marker, drawing with a ruler, notebooks, school bags, pencil, hand scissors, stationery, pencil sharpener and other school supplies.


GB 21027-2020 GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA ICS 97.180 Y 50 Replacing GB 21027-2007 Request in common use of security for student's articles ISSUED ON: JULY 23, 2020 IMPLEMENTED ON: FEBRUARY 01, 2022 Issued by: State Administration for Market Regulation; Standardization Administration of PRC. Table of Contents Foreword ... 3  1 Scope ... 6  2 Normative references ... 6  3 Terms and definitions ... 7  4 Requirements ... 7  5 Test method ... 10  6 Markings ... 13  Appendix A (Normative) List of harmful aromatic amines ... 14  Appendix B (Informative) Design guidelines for the ventilation area of the pen sleeve ... 15  Appendix C (Normative) Determination of benzene content in adhesives and correction products - Gas chromatography ... 17  Appendix D (Normative) Determination of toluene and xylene content in adhesives - Gas chromatography ... 20  Appendix E (Normative) Determination of total volatile organic compounds in adhesives ... 24  Appendix F (Normative) Air flow test ... 28  Appendix G (Informative) Examples of student's articles catalogues and corresponding requirements ... 30  Request in common use of security for student's articles 1 Scope This standard specifies the requirements, test methods, marking of student's articles. This standard applies to learning articles, which are used by students under the age of 14 (including 14 years old), including watercolor paints, crayons, oil pastels, colored clay, erasers, correction fluids, correction tapes, correction stickers, correction pens, liquid glues, solid glue, paste, watercolor pen, fountain pen, ink ballpoint pen, neutral ink ballpoint pen, water-based ink ballpoint pen, marker pen, whiteboard pen, highlighter, pencil, mechanical pencil, ink, lead core, plotter ruler (straightedge, triangle ruler, scale ruler, protractor, drawing template, excluding T-square), student compasses, schoolwork books, book covers, school bags, pencil bags, stationery scissors, stationery boxes, manual pencil sharpeners, pencil sharpeners, utility knifes, etc. This standard does not apply to stationery products, which are intended for students over 14 years old AND are used by professionals. 2 Normative references The following documents are essential to the application of this document. For the dated documents, only the versions with the dates indicated are applicable to this document; for the undated documents, only the latest version (including all the amendments) is applicable to this standard. GB/T 606 Chemical reagent - General method for the determination of water - Karl Fischer method GB/T 1033.1 Plastics - Methods for determining the density of non-cellular plastics - Part 1: Immersion method liquid pycnometer method and titration method GB/T 2793 Test method for nonvolatile content of adhesives GB 6675.2-2014 Safety of toys - Part 2: Mechanical and physical properties 4.4.2 Decomposable hazardous aromatic amine dyes are prohibited. The content of each hazardous aromatic amine shall not exceed 20 mg/kg. See Appendix A for the list of hazardous aromatic amines. 4.5 Limits of phthalate plasticizers in accessible plastic parts The total content of three phthalates: dihexyl phthalate (DEHP), dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), in accessible plastic parts, shall not exceed 1000 mg/kg. For a single sample, if the sampling size of a single material is less than 10 mg, it can be exempted. 4.6 The limit of free formic acid in colored clay The content of free formaldehyde, in the colored clay, shall not exceed 500 mg/kg. 4.7 Brightness (whiteness) of schoolwork books The brightness (whiteness) of the workbook shall not be greater than 85%. 4.8 Pen sleeve safety 4.8.1 General requirements The pen sleeve shall meet at least one requirement of 4.8.2 or 4.8.3. 4.8.2 Pen sleeve size When the pen sleeve enters the ring gauge, which has a diameter of mm AND a thickness of not less than 19 mm, vertically along the axis, under its own weight, the length of the pen sleeve, which does not enter the ring gauge, shall be at least 5 mm. Note: Pen sleeves, which comply with the requirements of this article, are considered large enough to not pose a risk of inhalation. 4.8.3 Air flow of pen sleeve When the maximum pressure difference, at room temperature, is 1.33 kPa, the air flow through the pen sleeve shall be at least 8 L/min, Note 1: When the pen sleeve relies on internal ventilation, a round hole which has a cross-sectional area of about 3.4 mm2 can meet this requirement, BUT multiple small holes may require a larger total cross-sectional area. Note 2: Appendix B gives guidelines for pen sleeves relying on external ventilation. Note 3: Pen sleeves, which comply with the requirements of this article, are considered not to pose a suffocation hazard. 4.9 Edge, tip 4.9.1 The top of stationery scissors and blades shall be arc tops, not sharp points. 4.9.2 For stationery scissors, manual pencil sharpeners, pencil sharpeners, student compasses, plotter rulers, utility knives, etc., if there are functional sharp edges and sharp points, due to indispensable functionality, it shall provide warning instructions. There shall be no other non-functional sharp edges and sharp points. Note: The writing tip of pencils and similar drawing tools is not considered a dangerous sharp tip. 4.9.3 The accessible edges, corners or parting lines of stationery boxes, etc. shall not have sharp burrs, sharp tips or overflows, OR they shall be protected, so that they cannot be touched. 4.9.4 For the accessible edges of student's articles, including holes and grooves, they shall not have dangerous burrs or beveled edges, OR use them as folded edges, curled edges, or formed of curved edges, OR be protected with permanent protective parts or coatings. 4.9.5 The accessible ends of exposed bolts or threaded rods shall not have exposed sharp edges or burrs, OR their ends shall be covered with smooth nuts, so that sharp edges and burrs cannot be touched. 5 Test method 5.1 Limits of migratable elements The determination of the content of migratable elements shall be carried out, in accordance with the provisions of GB 6675.4-2014. 5.2 Limits of harmful substances in liquid glue, solid glue, paste 5.2.1 The determination of free formaldehyde content in the adhesive shall be carried out, in accordance with the provisions of GB/T 32606. 5.2.2 The determination of the benzene content in the adhesive is carried out, in accordance with Appendix C. 5.2.3 The determination of toluene and xylene content in the adhesive is carried out, in accordance with Appendix D. Appendix C (Normative) Determination of benzene content in adhesives and correction products - Gas chromatography C.1 Overview This Appendix specifies the determination method of benzene content, in adhesives and correction products for students. C.2 Principle After the specimen is diluted with an appropriate solvent, use a micro-syringe, to directly inject the diluted specimen solution into the sampling device. Use the carrier gas to bring it into the chromatographic column, where it is separated into the corresponding components. Use the hydrogen flame ionization detector, to detect and record the chromatogram. Use the external standard method, to calculate the benzene content in the specimen solution. C.3 Reagents C3.1 Benzene: Chromatographically pure. C3.2 Ethyl acetate: Analytically pure. C.4 Instruments C.4.1 Injector: Micro-syringe. C.4.2 Chromatograph: Equipped with hydrogen flame ionization detector. C.4.3 Chromatographic column: Capillary column; the stationary liquid is dimethyl polysiloxane. Note: Where there are other components that are difficult to separate from the peaks of the tested component, switch to a column, which has a different polarity, to perform the test, under appropriate conditions. C.4.4 Recording device: Integrator or chromatography workstation. C.4.5 The measurement conditions are as follows: - Vaporization chamber's temperature: 200 °C; - Testing chamber's temperature: 250 °C; Appendix D (Normative) Determination of toluene and xylene content in adhesives - Gas chromatography D.1 Overview This Appendix specifies the determination method of toluene and xylene content, in adhesives for students. D.2 Principle After the specimen is diluted with an appropriate solvent, directly inject the diluted specimen solution into the sampling device, by the use of a micro syringe. Use the carrier gas to bring it into the chromatographic column, where it is separated into the corresponding components. Use the hydrogen flame ionization detector, to detect and record the chromatogram. Use the external standard method, to calculate the content of toluene and xylene, in the specimen solution. D.3 Reagents D.3.1 Toluene: Chromatographically pure. D.3.2 m-xylene and p-xylene: Chromatographically pure. D.3.3 o-xylene: Chromatographically pure. D.3.4 Ethyl acetate: Analytically pure. D.4 Instruments D.4.1 Sample injection device: Micro-syringe. D.4.2 Chromatograph: Equipped with hydrogen flame ionization detector. D.4.3 Chromatographic column: It shall be able to sufficiently separate the measured compounds. For example: Polydimethylsiloxane capillary column or similar models. Note: When there are other components, which are difficult to separate from the peaks of the tested component, switch to a column, which has a different polarity, to perform the test under appropriate conditions. D.4.4 Recording device: Integrator or chromatographic workstation. D.4.5 The measurement conditions are as follows: - Vaporization chamber's temperature: 200 °C; - Testing chamber's temperature: 250 °C; - Nitrogen: Purity greater than 99.99%; - Hydrogen: Purity greater than 99.99%; - Air: Silica gel to remove water; - Program heating: Initial temperature 35 °C; holding time 25 min; heating rate 8 °C/min; ending temperature 150 °C; holding time 10 mm. Note: Other measurement conditions, which achieve the separation effect, can be selected. D.5 Analytical procedures Weigh 0.5 g ~ 1.0 g (accurate to 0.1 mg) of the specimen. Place it in a 25 mL volumetric flask. Use ethyl acetate to dissolve and dilute it to the mark. Shake it well. Use a micro-syringe, to take 1 μL of injected sample. Measure its peak area. If the peak area of the specimen solution is greater than the peak area of the maximum concentration in Table D.1, use a pipette to accurately pipette V volume of the specimen solution, into a 50 mL volumetric flask. Use ethyl acetate to dilute it to the mark. Shake well before measurement. D.6 Preparation of standard solution D.6.1 Preparation of benzene series solution Toluene, meta-xylene, p-xylene, o-xylene standard solutions: 1.0 mg/mL, 1.0 mg/mL, 1.0 mg/mL. Respectively, weigh 0.1000 g of toluene, 0.1000 g of m-xylene and p-xylene, 0.1 g of (accurate to 0.1 mg) o-xylene. Place them in a 100 mL volumetric flask. Use ethyl acetate, to dilute it to the mark. Shake well. D.6.2 Preparation of series of standard solutions Add the volume of the standard solution (D.6.1), which is listed in Table D.1, into six 25 mL volumetric flasks. Use ethyl acetate to dilute it to the mark. Shake well. Appendix E (Normative) Determination of total volatile organic compounds in adhesives E.1 Overview This Appendix is suitable for the determination of total volatile organic compounds in adhesives for students. E2 Principle Put an appropriate amount of adhesive, in a blast drying oven, at a constant temperature. Determine the total volatile content of the adhesive, within a specified time. Use Karl Fischer method or gas chromatography, to determine the water content. The total volatile content of the adhesive is deducted by the amount of water in it, to calculate the total volatile organic content in the adhesive. E.3 Reagents E.3.1 Unless otherwise specified, only use reagents confirmed to be analytically pure AND distilled water or deionized water or water of equivalent purity in the analysis. E.3.2 Karl Fischer reagent. E.4 Instruments E.4.1 Blast drying oven: The temperature is controlled at 105 °C ± 1 °C. E.4.2 Karl Fischer titrator. E.4.3 Gas chromatograph: Equipped with thermal conductivity detector. E.5 Analytical procedures E.5.1 Determination of total volatile content Make determination, according to the method specified in GB/T 2793. E.5.2 Determination of moisture content in adhesive E.5.2.1 Karl Fischer method Make determination, according to the method specified in GB/T 606. E.5.2.2 Gas chromatography E.5.2.2.1 Reagents E.5.2.2.1.1 Distilled water. E.5.2.2.1.2 Anhydrous N,N-dimethylformamide (DMF), analytically pure. E.5.2.2.1.3 Anhydrous isopropanol, analytically pure. E.5.2.2.2 Instruments E.5.2.2.2.1 Gas chromatograph: Equipped with thermal conductivity detector. E.5.2.2.2.2 Chromatographic column: The column length is 1 m; the outer diameter is 3.2 mm; the stainless steel column is packed with polymer porous microspheres of 177 μm ~ 250 μm. (For program heating, the initial column temperature is 80 °C; the holding time is 5 min; the heating rate is 30 °C/min; the end temperature is 170 °C; the holding time is 5 min. For the constant temperature, the column temperature is 140 °C. After the isopropanol is completely extracted, adjust the column temperature to 170 °C. Wait for the DMF peak to come out. If the test continues, lower the column temperature to 140 °C. E.5.2.2.2.3 Recorder. E.5.2.2.2.4 Micro-syringe. E.5.2.2.2.5 Glass bottle with stopper: 10 mL, E.5.2.2.3 Test procedure E.5.2.2.3.1 Determination of water response factor R Weigh about 0.2 g of distilled water AND about 0.2 g of isopropanol (accurate to 0.1 mg). Put it in the same glass bottle with a stopper. Add 2 mL of N, N- dimethylformamide. Mix well. Use a micro-syringe to inject 1 μL of standard mixture. Record its chromatogram. Calculate the water response factor R, according to formula (E.1): Where: R - Response factor of water; mi - The mass of isopropanol, in grams (g); Appendix F (Normative) Air flow test F.1 Principle Fully insert the pen sleeve under test into an elastic hose, which has an appropriate diameter. When air flows through the hose, measure the pressure difference in two directions, respectively. F.2 Equipment F.2.1 Air source: the frequency is not limited; the air supply is at least 25 L/min, within the pressure range of 4 kPa ~ 50 kPa. F.2.2 The flow regulator: it can control the flow, which has an accuracy of ± 0.1 L/min. F.2.3 Flow meter: it is capable of measuring flow in the range of 5 L/min ~ 10 L/min, which has an accuracy of ±0.2 L/min. F.2.4 Pressure gauge, capable of measuring at least 4.00 kPa pressure, with an accuracy of ± 0.01 kPa. F.2.5 Connections and hoses: according to Figure F.1, connect the above equipment into a test device. F.2.6 Flexible hose: measure the widest part of the pen sleeve under test; select the hose, whose inner diameter is 80% ~ 85% of the circumscribed circle diameter of the pen sleeve under test; its wall thickness is (0.75 ± 0.25) mm; the Shore hardness A is (55 ± 10). Note: A hose, which has a diameter suitable for the pen sleeve, may be difficult to obtain. If necessary, the hose can be manufactured by dip molding technology. F.3 Procedure F.3.1 Cut an elastic hose, which has an appropriate length (see F.2.6), so that when the pen sleeve is inserted and connected to the test device, there is a loose space at both ends of the pen sleeve. Coat the inner wall of the hose, with soapy water or other suitable low-viscosity lubricant. The pen sleeve shall be inserted into the middle of the hose; try to keep it parallel to the axis of the hose. ......


GB 21027-2007 GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA ICS 97.180 Y 50 Request in common use of security for student’s articles ISSUED ON. JUNE 07, 2007 IMPLEMENTED ON. APRIL 1, 2008 Issued by. General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China; Standardization Administration of the People’s Republic of China. Table of Contents Foreword ... 3 1 Scope ... 4 2 Normative references ... 4 3 Requirements... 5 4 Test methods ... 7 5 Inspection rules ... 8 6 Markings and instructions ... 9 Annex A (normative) Determination of free formaldehyde content in adhesives - Acetylacetone spectrophotometric method ... 10 Annex B (normative) Determination of benzene content in adhesives - Gas chromatographic method ... 14 Annex C (normative) Determination of toluene and xylene content in adhesives - Gas Chromatographic method ... 17 Annex D (normative) Determination of the content of total volatile organic compounds in adhesives ... 20 Annex E (normative) Determination of air circulation ... 22 Foreword All technical contents of this Standard are mandatory. Annexes A, B, C, D, and E of this Standard are normative. This Standard is proposed by China Light Industry Federation. This Standard is under the jurisdiction of National Standardization Center of Stationery and Sporting Goods. Drafting organizations of this Standard. Shanghai Siic Marie Painting Materials Co., Ltd., Fujian New Generation Industrial Co., Ltd., Ningbo Songhe Stationery Co., Ltd., Tianjin Global Technology Packaging Paper Co., Ltd., Shanghai Genvana Industrial Development Co., Ltd., Qingdao Changlong Stationery Co., Ltd., Ruhe Stationery (Shenzhen) Co., Ltd. Main drafters of this Standard. Wang Yuren, Zhu En, Zheng Chengqiang, Chen Xiongfei, Zheng Ping, Fang Hanben, Kang Dengkui, Zhuang Hong. This Standard is issued for the first time. Request in common use of security for student’s articles 1 Scope This Standard specifies the safety requirements, test methods, inspection rules, marking and instructions of student’s articles. This Standard is applicable to student’s articles such as watercolor paints, crayons, oil pastels, finger paints, plasticine, erasers, correction products (correction fluid, correction tape, correction pen), adhesives, watercolor pens, writing pens, marker pens, rulers for drawing, notebooks, school bags, pencil cases, hand scissors, stationery cases, pencil sharpeners for underage students. 2 Normative references The following standards contain provisions which, through reference in this Standard, constitute provisions of this Standard. For dated reference, subsequent amendments to (excluding corrections to), or revisions of, any of these publications do not apply. However, the parties to agreements 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 601-2002 Chemical reagent - Preparations of standard volumetric solutions GB/T 606-2003 Chemical reagent - General method for the determination of water - Karl Fischer method (neq ISO 6353-1.1982) GB/T 2793-1995 Test method for nonvolatile content of adhesives GB/T 2912.1-1998 Textiles - Determination of formaldehyde - Part 1. Free and hydrolyzed formaldehyde (Water extraction method) (ISO/FDIS 14184-1.1997, EQV) GB 5296.5-2006 Instructions for use of products of consumer interest - Part 5. Toys GB 6675-2003 National safety technical code for toys GB/T 7974-2002 Paper, board and pulp - Measurement of brightness - Diff/Geometry (ISO 2470.1999, NEQ) be no dangerous burrs or oblique sides, or they shall be folded, curled or formed to be curved edges, or protected by permanent protectors or coating. 3.8.5 Touchable ends of exposed bolts or threaded rods shall be no exposed sharp edges or burrs, or the ends thereof shall be covered with smooth nuts so that sharp edges and burrs are protected from being touched. 4 Test methods 4.1 Determination of maximum limit of migratable elements is carried out according to the specifications of Annex C of GB 6675-2003. The analysis correction coefficient of each element is in accordance with Table C.2 of GB 6675-2003; 1.1.1-trichloroethane is changed to n-heptane. 4.2 Determination of benzene content and chlorinated hydrocarbon content of organic solvents in correction products is carried out according to the method specified in GB/T 9722-2006. 4.3 Determination of limits of harmful substances in adhesives. 4.3.1 Determination of free formaldehyde content in adhesives is carried out according to Annex A. 4.3.2 Determination of benzene content in adhesives is carried out according to Annex B. 4.3.3 Determination of toluene and xylene content in adhesives is carried out according to Annex C. 4.3.4 Determination of total volatile organic content in adhesives is carried out according to Annex D. 4.4 Determination of formaldehyde content in fabrics and accessories used for school bags and pen bags is carried out according to the specifications of GB/T 2912.1-1998. 4.5 Determination of brightness (whiteness) of notebooks is carried out according to the specifications of GB/T 7974-2002. 4.6 Safety of capping 4.6.1 Size of cap Measure with an annular gauge with a diameter of 16ି଴ା଴.଴ହ mm. 4.6.2 Ventilation area of cap Annex A (normative) Determination of free formaldehyde content in adhesives - Acetylacetone spectrophotometric method A.1 Scope This method specifies the method for the determination of free formaldehyde content in adhesives for students. This method is applicable for adhesives for students with free formaldehyde content greater than 0.005 %. A.2 Principle The water-based adhesive is dissolved in water, and the solvent-based adhesive is first dissolved in ethyl acetate and then dissolved in water. The free formaldehyde dissolved in water is distilled off with water under acidic conditions. In the acetic acid- ammonium acetate buffer solution with pH = 6, the formaldehyde reacts with acetylacetone in the distillate, and the stable yellow compound is rapidly produced under the boiling water bath. After cooling, the absorbance is measured at 415. 40nm. The free formaldehyde content in the sample is calculated according to the standard curve. A.3 Reagents Unless otherwise stated, only the reagents identified as analytical reagents and distilled or deionized water or water of comparable purity are used in the analysis. A.3.1 Ammonium acetate. A.3.2 Glacial acetic acid. ρ = 1.055 g/mL. A.3.3 Acetylacetone. ρ = 0.975 g/mL. Acetylacetone solution. 0.25 % (volume fraction). WEIGH 25 g of ammonium acetate (A.3.1); ADD a small amount of water to dissolve; ADD 3 mL of glacial acetic acid (A.2.3) and 0.25 mL of acetylacetone (A.3.3); MIX and then add water to adjust pH to 6.0. The solution is adjusted to pH 2 ~ pH 5 for storage, and can be stable for a month. A.3.4 Hydrochloric acid solution. 1 + 5 (V + V). A.3.5 Sodium hydroxide solution. 30 g/100 mL. A.3.6 Iodine (I2). Iodine solution. c(l2) = 0.1mol/L, prepare according to GB/T 601-2002. INSTALL the distillation device; DISTILL in an oil bath, STOP the distillation until the distillate is 20mL. TRANSFER the distillate into a 250-mL volumetric flask; DILUTE to the scale with water. TAKE 10 mL of distillate in a 25-mL volumetric flask; ADD 5 mL of acetylacetone solution (A.3.3); DILUTE to the scale with water; SHAKE well. PLACE it in boiling water for 3 mm; REMOVE and cool to room temperature. MEASURE its absorbance. A.5.2.2 Solvent-based adhesives WEIGH 5.0 g of the sample (accurate to 0.1 mg); PLACE in a 500-mL distilled flask; ADD 20 mL of ethyl acetate (A.3.11) to dissolve; ADD 250 mL of water; ADD 5 mL of phosphoric acid (A.3.10); SHAKE well. INSTALL the distillation device; DISTILL in an oil bath, STOP the distillation until the distillate is 20mL. TRANSFER the distillate into a 250-mL volumetric flask; DILUTE to the scale with water. TAKE 10 mL of distillate in a 25-mL volumetric flask; ADD 5 mL of acetylacetone solution (A.3.3); DILUTE to the scale with water; SHAKE well. PLACE it in boiling water for 3 mm; REMOVE and cool to room temperature. MEASURE its absorbance. A.6 Results presentation The concentration of formaldehyde in the sample solution is read directly from the standard curve. Calculate the content of free formaldehyde X in the sample according to equation (A.2). where. X - the content of free formaldehyde, in grams per kilogram (g/kg); ct - the concentration of formaldehyde in the sample solution read from the standard curve, in micrograms per milliliter (μg/mL); cb - the concentration of formaldehyde in t... ......

Similar standards: GB/T 26711-2024  GB/T 26717-2024  
Similar PDFs (Auto-delivered in 9 seconds): GB 21027-2020  GB/T 26704-2011  GB/T 26714-2011  GB/T 37624-2019