GB/T 2441.3-2001 Urea determination method Determination of water content Karl Fischer method GB/T2441.3-2001 Standard download decompression password: www.bzxz.net
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GB/T2441.3--2001 This standard is a revision of GB/T2444-1991 "Determination of water content in urea by Karl Fischer method". This standard is equivalent to ISO2753:1973 "Determination of water content in industrial urea by Karl Fischer method". This standard is the third part of GB/T2441 "Determination method of urea". GB/T2441 also includes the following parts: Part 1 GB/T2441.1—2001 Part 2 GB/T2441.2-2001 GB/T 2441.4-2001 Part 4 Part 5 GB/T2441.5—2001 GB/T2441.6—2001 Part 6 Part 7 Part 8 GB/T 2441.7- —2001 GB/T 2441.8--2001 GB/T 2441. 9--2001 Part 9. Urea determination method Urea determination method Urea determination method Urea determination method Urea determination method Urea determination method Urea determination method This standard shall replace GB/T 2444-1991 from the date of implementation. Determination of total nitrogen content Determination of bisphenol A content Spectrophotometric method Determination of iron content O-phenanthroline spectrophotometric method Determination of alkalinity Volumetric method Determination of water-insoluble matter content Gravimetric method Determination of particle size Sieving method Determination of sulfate content Visual turbidimetry Determination of methylene diphenol content Spectrophotometric method This standard is proposed by the State Bureau of Petroleum and Chemical Industry. This standard is under the jurisdiction of the National Technical Committee for Standardization of Fertilizers and Soil Conditioners and is responsible for its interpretation. The drafting units of this standard are: National Fertilizer Quality Supervision and Inspection Center (Shanghai), PetroChina Urumqi Petrochemical Company Fertilizer Plant, Sinopec Jiujiang Branch, Hainan Fudao Chemical Co., Ltd. The main drafters of this standard are: Zhang Qiuzhen, Jiang Jianxin, Yang Jiqun, Guo Zucao, Sha Yanping. This standard was first published in 1981. GB/T2441.3---2001 ISO Foreword ISO (International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The development of international standards is usually carried out through ISO's technical committees. Every member body interested in the subject of an established technical committee has the opportunity to join the technical committee, and governmental or non-governmental international organizations in contact with ISO may also participate in this work. Draft international standards adopted by technical committees shall be circulated to member bodies for approval before being approved as international standards by the ISO Council. ISO2753 international standard was drafted by ISO/TC47 Chemical Technical Committee and sent to member units in June 1972. This standard has been adopted by member units in the following countries:Austria Belgium Hungary Ireland Bulgaria Italy Israel Portugal Romania New Zealand Turkey The International Union of Pure and Applied Chemistry (IUPCA) also agreed to this standard. No member country disagreed with this international standard. 79 1 Scope National Standard of the People's Republic of China Determination of urea Determination of water content-Kar! Fischer method This standard specifies the determination of water content in urea by Karl Fischer method. This standard is applicable to the determination of water content in industrial and agricultural urea prepared by the reaction of ammonia and carbon dioxide. In the case of arbitration, Karl Fischer reagent containing pyridine is used. 2 Reference standards GB/T2441.3—2001 eqv ISO 2753:1973 Replacement GB/T 2444—1991 The provisions contained in the following standards are used in this standard through the use of the number 1 in this standard to constitute the provisions of this standard. When this standard was published, the versions shown were valid. All standards are subject to revision. Parties using this standard should explore the possibility of using the latest version of the following standards. GB/T6283-1986 Determination of water content in chemical products Karl Fischer method (general method) (eqVISO760: 1978) HG/T2843-1997 Common standard titration solutions, standard solutions, reagent solutions and indicator solutions in chemical analysis of fertilizer products 3 Principle The water present in the sample reacts quantitatively with the Karl Fischer reagent of known water titer. The reaction formula is as follows; H,0--12+SO+3C,HsN-+2CH.NHI+CH,NS0C,HN SO, +CH,OH --CHNH · OSO,OCH4 Reagents The reagents, solutions and water used in this test method shall comply with the requirements of HG/T2843 unless otherwise specified. 4.1 Karl Fischer reagent: 4.1.1 Karl Fischer reagent containing pyridine; 4.1.2 Karl Fischer reagent without pyridine: 4.2 Methanol (dehydrated) 4.3 Sodium tartrate dihydrate. 5 Apparatus Karl Fischer direct coulometric titration apparatus, the typical device of which shall be configured in accordance with GB/T6283. 6 Analysis Procedure 6.1 Standardization of Karl Fischer Reagent Approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on July 26, 200180 Implementation on January 1, 2002 GB/T 2441.3—2001 6.1.1 Standardization of general Karl Fischer reagent containing pyridine: Use water or sodium tartrate dihydrate to standardize the titer T of the reagent against water according to the procedures specified in GB/T6283. 6.1.2 Standardization of Karl Fischer reagent without pyridine: Use water to standardize the titer T of the reagent against water according to the procedures specified in GB/T6283. 6.2 Determination Weigh 1 to 5 g of laboratory sample (accurate to 0.001 g) with a weighing tube. The volume of Karl Fischer reagent consumed by the weighed sample is required to not exceed 10 mL. Drain the residual liquid in the titration container through the drain nozzle of the Karl Fischer instrument, add 50mL of methanol to the titration container, the amount of methanol must be enough to submerge the electrode, turn on the electromagnetic stirrer, and titrate with Karl Fischer reagent until the ammeter produces the same deflection as during calibration, and keep it stable for 1 minute. Open the rubber stopper of the feed port, quickly pour the weighed sample in the weighing tube into the titration container, immediately cover the rubber stopper, stir until the sample is dissolved, and titrate with Karl Fischer reagent to the end point as described above for titrating the amount of water in methanol, and record the volume of Karl Fischer reagent consumed (V). Weigh the mass of the weighing tube after adding the sample to determine the mass of the sample used (m). 7 Expression of analysis results The water content (X) in the sample is expressed as the mass fraction of water (HO) (%), calculated according to formula (1): TV × 100- m × 1 000 Wherein: V. Volume of Karl Fischer reagent consumed in titration, mL; T——Titer of Karl Fischer reagent for water, mg/mL; TV m× 10 Mass of the sample, g. Take the arithmetic mean of the parallel determination results as the determination result, and express the result to two decimal places. 8 Allowable differenceWww.bzxZ.net The absolute difference of the parallel determination results shall not exceed 0.03%. ( Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.