GB/T 4348.3-2002 Determination of sodium ferric hydroxide content for industrial use - 1,10-phenanthroline spectrophotometric method

This standard specifies the method for determining the iron content in industrial sodium hydroxide by 1,10-phenanthroline spectrophotometry. This standard applies to all levels of industrial sodium hydroxide products with an iron content greater than or equal to 0.000 05%. GB/T 4348.3-2002 Determination of the iron content of industrial sodium hydroxide by 1,10-phenanthroline spectrophotometry GB/T4348.3-2002 Standard download decompression password: www.bzxz.net

GB/T 4348.3—2002
Foreword
This standard is equivalent to the international standard ISO983:1974 (1997) "Determination of iron content in industrial sodium hydroxide by 1,10-phenanthroline photometric method" revised from the national standard GB/T4348.3--1984 "Determination of iron content in industrial sodium hydroxide by o-phenanthroline photometric method".
The main technical difference between this standard and ISO983:1974 (1997) is that p-nitrophenol indicator solution is used instead of methyl orange indicator as the neutralization indicator, eliminating the use of bromine water for decolorization, which causes personal injury and environmental pollution.
Adjustment.
The sampling volume is different; this standard stipulates that the liquid sample is 25g~~30g, the solid sample is 15g~20g, and the reagent dosage is adjusted. The main technical differences between this standard and GB/T4843.3--1984 are: the reducing agent used in this standard is hydroxylamine hydrochloride; the previous version is ascorbic acid. This standard stipulates that the liquid sample is 25g~30g, and the solid sample is 15g~20g: the previous version took 10g of sample. From the date of implementation, this standard will replace GB/T4348.3-1984. This standard is proposed by the China Petroleum and Chemical Industry Association. This standard is under the jurisdiction of the National Chemical Standardization Technical Committee Chlor-Alkali Branch (TC63/SC6). The responsible drafting units of this standard are: Jinxi Chemical Research Institute, Heilongjiang Qihua Chemical Co., Ltd. The main drafters of this standard are: Hu Liming, Lv Hua, Chen Peiyun, Li Furong. This standard was first issued in 1984.
GB/T 4348.3—2002
ISO Foreword
ISO (International Organization for Standardization) is a worldwide federation of national standards associations (ISO member bodies) that conducts international standards work through ISO technical committees. Member bodies interested in projects for which a technical committee has been established have the right to send representatives to the technical committee. International organizations, including governmental and non-governmental organizations, may also participate in this work by contacting ISO. Draft international standards adopted by technical committees are circulated to member states for voting before being accepted as international standards by the ISO Council.
International Standard ISO983 was drafted by Technical Committee ISO/TC47 on Chemistry and notified to member states in September 1973. The following national bodies have expressed agreement:
Austria
Belgium
Bulgaria
Czechoslovakia
Hungary
Ireland
Israel
New Zealand
Portugal
Romania
Turkey
Yugoslavia
This standard is also recognized by the International Union of Pure and Applied Chemistry (IUPAC). No member states have expressed objections.
This standard is a technical revision of ISO Recommendation R 983:1969 and replaces that recommendation. 107
National Standard of the People's Republic of China
Sodium hydroxide for industrial use
Determination of iron content
1, 10-phenanthroline spectrophotometric method
Sodium hydroxide for industrial use--Determination of iron content-1, 10-Phenanthroline photometric method1Scope
GB/T 4348.3-2002
eqv Iso 983:1974(1997)
Replaces GB/T4348.3-1984
This standard specifies the method for determining the iron content in sodium hydroxide for industrial use by 1, 10-phenanthroline spectrophotometric method. This standard is applicable to all grades of industrial sodium hydroxide products with an iron content greater than or equal to 0.00005% by mass. 2 Reference 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. GB/T603-1988 Preparation of preparations and products used in chemical reagent test methods (neqISO6353-1:1982) GB/T604-1988 Chemical reagent acid-base indicator pH color range determination general method GB/T6682-1992 Specification and test method for water for analytical laboratories (eqvISO3696:1987) 3 Principle
Use hydroxylamine hydrochloride to reduce Fe3+ in the sample solution to Fe?+. In a buffer solution (pH=4.9) system, Fe2 and 1,10-phenanthroline form an orange-red complex. The absorbance of the complex is measured at a wavelength of 510nm. The reaction formula is as follows: 4Fe*++2NH,·OH\4Fe2++N,0+H,O+4H+Fe?+ + 3C12HgN, →[Fe(C12HgN,),]2+4 Reagents and materials
The reagents and water used in this method are analytically pure reagents and grade 3 water specified in GB/T 6682. The standard solutions, preparations and products required in the test, except those specified in this standard, are prepared in accordance with the provisions of GB/T603 and GB/T604. 4.1 Hydrochloric acid.
4.2 Ammonia water.
4.3 Sulfuric acid.
4.4 Hydroxylamine hydrochloride solution: 10g/L.
4.5 Acetic acid Sodium acetate buffer solution: pH -4.9. Weigh 272g sodium acetate (CH.COONa·3H,O), dissolve in water, add 240mL glacial acetic acid, and dilute to 1000mL. 4.6 Iron standard solution: 1ml. Contains 0.200mg iron. Weigh 1.4043g of ammonium ferrous sulfate [(NH)2Fe(SO.)2·6H,O], accurate to 0.0001g, dissolve in 200mL of water, add 20mL of sulfuric acid (4.3), cool to room temperature, transfer to a 1000mL volumetric flask, dilute to scale, and shake well. 4.7 Iron standard solution: 1mL contains 0.010mg of iron. Approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on 2002-05-29 108
2002-12-01 implementation
GB/T 4348.3—2002
Take 25.00mL of iron standard solution (4.6), transfer to a 500mL volumetric flask, dilute to scale, and shake well. This solution must be prepared before use.
4.8 p-Nitrophenol solution: 2.5g/L.
4.9 1,10-phenanthroline solution: 2.5g/L. 5 Instruments
General laboratory instruments and spectrophotometer. 6 Operating steps
6.1 Drawing of standard curve
6.1.1 Preparation of standard reference solution
Take 0.0, 1.0mL, 2.5mL, 4.0mL, 5.0mL, 8.0mL, 10.0.ml1:2.0.mL, 15.0mL of iron standard solution (4.7) in 100mL volumetric flasks, add 0.5mL hydrochloric acid (4.1) and about 50mL water to each volumetric flask, then add 5mL hydroxylamine hydrochloride, 20mL buffer solution and 5mL of 1,10-phenanthroline solution, dilute to scale with water and spread evenly. Let stand for 10min. 6.1.2 Determination of absorbance of standard reference solution
Use reference solution without adding iron standard solution to adjust the absorbance of the instrument to zero. At a wavelength of 510nm, select colorimetric blood of corresponding specifications according to the iron content range of the sample to be measured, see Table 1 to determine the absorbance of the standard reference solution. Table 1
Mass fraction of ferric oxide/%
0.005~~0.01
0.01~0.015
0.015~0.03
Specification of colorimetric blood/cm
Use the mass of iron (mg) contained in 100mL standard reference solution as the abscissa and the corresponding absorbance as the ordinate to draw a standard curve. 6.2 Sampling
Use a weighing bottle to weigh 15g~20g of solid or 25g~~30g of liquid sodium hydroxide sample, accurate to 0.01g. 6.3 Determination
6.3.1 Blank test
In a 500mL beaker, add 25mL of water and an equal amount of hydrochloric acid (4.1) to the neutralized sample (6.2), add 2~3 drops of p-nitrophenol indicator solution, then neutralize with ammonia (4.2) until light yellow, add hydrochloric acid (4.1) drop by drop until the solution is colorless, then add 2mL in excess, boil for 5min, cool to room temperature, transfer to a 250mL volumetric flask, dilute with water to the mark, and shake. Then proceed as described in (6.3.3). 6.3.2 Preparation of sample solution
Place the weighed sample (6.2) in a 500mL beaker, add water to dissolve to about 120mL, add 2-3 drops of p-nitrophenol indicator solution, neutralize with hydrochloric acid (4.1) until the yellow color disappears, add 2mL in excess, boil for 5min, cool to room temperature, place in a 250mL volumetric flask, dilute to scale with water, shake well. Then proceed according to (6.3.3). 6.3.3 Color development
Place 50.00mL of sample solution (6.3.2) in a 100mL volumetric flask, add 5mL of hydroxylamine hydrochloride, 20mL of buffer solution and 5mL of 1,10-phenanthroline solution, dilute to scale with water, shake well. Let stand for 10 min. 6.3.4 Determination of sample absorbance
Determine the absorbance of the solution (6.3.3) as described in (6.1.2). Before determination, adjust the instrument absorbance to zero with the blank test solution (6.3.1). 109
Result presentationwww.bzxz.net
GB/T4348.3--2002
The mass fraction of iron, X, is expressed in milligrams per gram (mg/g) and is calculated according to formula (1): XmX
Where: m, -
250× 1 000
The mass of iron corresponding to the absorbance of the test solution, mg The mass of the sample, g.
5000ml
or the ferric oxide content X expressed as mass fraction (%), calculated according to formula (2): X = 1. 429 7 × 10-4X
wherein: 1.4297-
8 allowable difference
conversion coefficient of iron and ferric oxide.
The absolute value of the difference between parallel determination results should not exceed the following values: X,≤0. 002 0% : 0. 000 1%
X1>0. 002 0% :0. 000 5%
Take the arithmetic mean of the parallel determination results as the reported result. 110
（1）
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