GB/T 2441.4-2001 Urea determination method Determination of iron content O-phenanthroline spectrophotometric method GB/T2441.4-2001 Standard download decompression password: www.bzxz.net

ICS.65.080
National Standard of the People's Republic of China
GB 2441.4—2001
Determination of ureaDetermination of iron content-1,10-Phenanthrolinespectrophotometric method2001-07-26Promulgated
General Logistics Department of Quality Supervision, Inspection and Quarantine of the People's Republic of China
Implementation on 2002-01-01
GB/T2441.4—2001
This standard is a revision of GB/T2445—1991 "Determination of iron content of industrial urea-1,10-Phenanthroline spectrophotometric method". This standard adopts ISO6685:1982 "Determination of iron content in industrial urea - o-phenanthroline spectrophotometric method" in a non-equivalent manner. The main technical differences between this standard and ISO6685:1982 and GB/T2445-1991 are as follows: 1. It quotes the basic standard HG/T2843-1997 for the chemical industry and no longer quotes the GB/T601 series of standards. 2. The sample weight is specified in the analysis procedure; the use of a pH meter to adjust the pH value of the solution is not specified. This standard is Part 4 of GB/T2441 "Determination of urea". GB/T2441 also includes the following parts:
GB/T2441.1—2001
Part 1:
Part 2
Part 3
Part 5
Part 6
Part 7
Part 8
Part 9
GB/T2441.2—2001
GB/T2441.3—2001
GB/T2441.5—2001
GB/T2441.6—2001
GB/T2441.7—2008
GB/T2441.8—2009
GB/T2441.9—2010 01
GB/T2441.8—2001
GB/T2441.9—2001
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Determination of water contentKarl Fischer method
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This standard shall replace GB/T2445—1991 from the date of implementation. This standard is proposed by the State Administration of Petroleum and Chemical Industry. Determination of alkalinity Volumetric method
Determination of water-insoluble content Gravimetric method
Determination of particle size Sieving method
Determination of sulfate content Visual turbidimetry
Determination of methylene diurea content Spectrophotometric method 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, Sha Yanping, Yang Jiqun. This standard was first issued in 1981.
GB/T2441.4—2001
ISO Foreword
ISO (International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The formulation of international standards is usually carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the opportunity to join the technical committee. International organizations, governmental or non-governmental, in liaison with ISO may also take part in the work. Draft international standards adopted by the technical committee are circulated to the member bodies for approval before being approved as international standards by the ISO Council.
ISO 6685 International Standard was prepared by ISO/TC47 Technical Committee on Chemistry and circulated to member bodies in October 1979. This standard has been adopted by member bodies in the following countries: Australia
Australia
Belgium
Czechoslovakia
Hungary
Italy
Philippines
Portugal
No member state disagrees with this document.
Romania
Yugoslavia
1 Scope
National Standard of the People's Republic of China
Determination of urea-Determination of iron content1,10-PhenanthrolinespectrophotometricmethodThis standard specifies the determination of iron content in industrial urea by 1,10-Phenanthrolinespectrophotometricmethod. This standard is applicable to the determination of iron content in industrial urea synthesized from ammonia and carbon dioxide. 2 Referenced Standards
GB/T2441.4—2001
neqIS06685:1982
Replaces GB/T2445—1991
The provisions contained in the following standards constitute the provisions of this standard by reference in this standard. When this standard was published, the versions shown were valid. All standards will be revised. All parties using this standard should explore the possibility of using the latest version of the following standards. HG/T2843-1997 Commonly used standard titration solutions, standard solutions, reagent solutions and indicator solutions in chemical analysis of fertilizer products 3 Principle
Use ascorbic acid to reduce the trivalent iron ions in the test solution to divalent iron ions. At pH 2-9 (pH 4.5 is selected in this standard), the divalent iron ions react with o-phenanthroline to form an orange-red complex. The absorbance is measured by a spectrophotometer at an absorption wavelength of 510nm. 4 Reagents and solutions
Unless otherwise specified, the reagents, solutions and water used in this test method shall comply with the requirements of HG/T2843. 4.1 Hydrochloric acid solution, 1+1;
4.2 Ammonia solution, 1+1;
4.3 Acetic acid-sodium acetate buffer solution, pH~4.54.4 Ascorbic acid solution, 20g/L (the solution can be used for 10 days);4.5 O-phenanthroline solution, 2g/L;
4.6 Iron standard solution, 0.100mg/mL;
4.7 Iron standard solution, 0.010mg/mL, dilute the iron standard solution (4.6) 10 times, only for use on the same day. 5 Instruments
General laboratory instruments and
Spectrophotometer with 3cm or 1cm absorption cell. 6 Analysis steps
6.1 Drawing of standard curve
6.1.1 Preparation of standard colorimetric solution
Approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on July 26, 2001, implemented on January 1, 2002
GB/T2441.4—2001
As shown in Table 1, add the given volume of iron standard solution (4.7) to 7 100mL volumetric flasks respectively. Each volumetric flask is treated in the same way as follows: add water to about 40mL, adjust the pH of the solution to close to 2 with hydrochloric acid solution, add 2.5mL ascorbic acid solution, 10mL acetic acid-sodium acetate buffer solution, 5mL o-phenanthroline solution, dilute to the scale with water, and shake well. Table 1 Amount of iron standard solution addedWww.bzxZ.net
Amount of iron standard solution used, mL
6.1.2 Absorbance determination
Corresponding iron content ug
Use a solution with zero iron content as the reference solution, and determine the absorbance of the standard colorimetric solution (6.1.1) at a wavelength of 510nm using a 1cm or 3cm absorption cell in a spectrophotometer. 6.1.3 Drawing of standard curve
Use the iron content (μug) in 100mL of the standard colorimetric solution as the horizontal axis and the corresponding absorbance as the vertical axis to draw a graph, or find the linear regression equation.
6.2 Determination
6.2.1 Preparation of test solution
Weigh about 10g of laboratory sample (accurate to 0.01g), place in a 100mL beaker, add a small amount of water to dissolve the sample, add 10mL of hydrochloric acid solution, heat to boil, and keep stable for 3min. After cooling, filter the test solution quantitatively into the 100mL beaker, wash with a small amount of water several times, and make the solution volume about 40mL.
Adjust the pH of the solution to about 2 with hydrogen aqueous solution, transfer the solution quantitatively to a 100mL volumetric flask, add 2.5mL ascorbic acid solution, 10mL acetic acid-sodium acetate buffer solution, 5mL o-phenanthroline solution, dilute to the mark with water, and mix. Note: If the iron content of the sample is <15ug, 5.00mL iron standard solution (4.7) can be added before adjusting the pH, and then deducted from the result. 6.2.2 Blank test
Carry out a blank test according to the above steps. Except for not adding the sample, the operating procedures and reagents used are the same as those for the determination. 6.2.3 Absorbance determination
The absorbance of the test solution and the blank test solution is determined in the same way as the steps for drawing the standard curve. 7 Expression of analytical results
Find out the iron content corresponding to the measured absorbance from the standard curve or the iron content calculated from the curve coefficient. The iron content (x) in the sample is expressed as the mass fraction (%) of iron (Fe) and is calculated according to formula (1): X = ml = m2 × 100
Wherein: ml-
= the mass of iron measured in the sample,;
= the mass of iron measured in the blank test,;- the mass of the sample,.
Take the arithmetic mean of the parallel determination results as the determination result, and express the result to five decimal places. 2
（1）
Allowance
GB/T2441.4—2001
The absolute difference of parallel determination results shall not exceed 0.00030%; if the determination result is less than 0.00030%, the relative error of parallel determination results shall not exceed 100%;
The absolute difference of determination results between different laboratories shall not exceed 0.00040%; if the determination result is less than 0.00040%, its relative error shall not exceed 100%.
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