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GB/T 11200.1-2006 English PDF (GBT11200.1-2006)

GB/T 11200.1-2006 English PDF (GBT11200.1-2006)

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GB/T 11200.1-2006: Sodium hydroxide for industrial use -- Determination of sodium chlorate content -- O-Tolidine spectrometric method

This Standard specifies the method of determining sodium chlorate content in sodium hydroxide for industrial use. This Standard is applicable to products with a mass fraction of sodium chlorate 0.00005% ~ 0.01% in sodium hydroxide for industrial use.
GB/T 11200.1-2006
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 71.060.40
G 11
Replacing GB/T 11200.1-1989
Sodium Hydroxide for Industrial Use - Determination of
Sodium Chlorate Content - o-Tolidine Spectrometric
Method
ISSUED ON: SEPTEMBER 14, 2006
IMPLEMENTED ON: FEBRUARY 1, 2007
Issued by: General Administration of Quality Supervision, Inspection and Quarantine of the PEOPLE Republic of China;
Standardization Administration of the PEOPLE Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Method Summary ... 4
4 Reagents ... 4
5 Instruments ... 5
6 Analytical Procedures ... 6
7 Result Calculation ... 7
8 Tolerances ... 7
9 Test Report ... 7
Sodium Hydroxide for Industrial Use - Determination of
Sodium Chlorate Content - o-Tolidine Spectrometric
Method
1 Scope
This Standard specifies the method of determining sodium chlorate content in sodium hydroxide for industrial use.
This Standard is applicable to products with a mass fraction of sodium chlorate 0.00005% ~ 0.01% in sodium hydroxide for industrial use.
2 Normative References
The clauses of the following documents become clauses of this Standard through the normative references in this Standard. In terms of references with a specified date, all subsequent amendments (excluding errata content) or revisions do not apply to this Standard. However, the various parties that reach an agreement in accordance with this Standard are encouraged to explore whether the latest versions of these documents are applicable. In terms of references without a date, the latest versions apply to this Standard.
GB/T 602 Chemical Reagent - Preparations of Standard Solutions for Impurity (GB/T 602- 2002, ISO 6353-1:1982, NEQ)
GB/T 603 Chemical Reagent - Preparations of Reagent Solutions for Use in Test Methods (GB/T 603-2002, ISO 6353-1:1982, NEQ)
3 Method Summary
In a strong acid medium, sodium chlorate decomposes into chlorine gas and chlorine dioxide; under the condition of pH < 1.3, chlorine gas and chlorine dioxide react with o-tolidine to generate a stable yellow complex; use a spectrophotometer to determine the absorbance. 4 Reagents
Unless it is otherwise stated, only reagents confirmed to be analytically pure and deionized water or water of equivalent purity are used in the analysis.
The container used for sodium chlorate analysis in this method shall avoid contact with rubber or other organic matters.
4.1 Hydrochloric acid: high-grade purity.
4.2 Sodium hydroxide solution: 400 g/L.
4.3 Sodium chlorate standard solution: 1 g/L.
Weigh-take 1.000 g of sodium chlorate, transfer it into a 1,000 mL volumetric flask, then dilute to the scale.
4.4 Sodium chlorate standard solution: 10 mg/L.
Measure-take 5.00 mL of sodium chlorate standard solution (4.3), place it in a 500 mL volumetric flask, then dilute to the scale. This solution shall be prepared before use. 4.5 O-tolidine indicating solution: 1 g/L.
Weigh-take 0.5 g of o-tolidine, place it in a mortar; add a small amount of mixed solution of 50 mL of hydrochloride acid (4.1) and 200 mL of water for grinding, then, transfer it together with the remaining mixed solution into a 500 mL beaker. Add 150 mL of water, heat it while stirring. After dissolving, transfer all the solution into a 500 mL brown volumetric flask, and use water to dilute to the scale.
This solution shall be stored in a brown bottle in the dark. It shall remain valid for 3 months. 5 Instruments
General laboratory instruments and the following instruments.
5.1 Separating funnel.
5.2 Two-mouth flask: 500 mL.
5.3 Water bath: controllable at (50 ??? 2) ???C.
5.4 Spectrophotometer.
a---two-mouth flask;
b, c---separating funnel.
Figure 1 -- Schematic Diagram of Determination Device of Sodium Chlorate 6 Analytical Procedures
6.1 Drawing of Standard Curve
6.1.1 Respectively add 0 mL, 0.5 mL, 1.0 mL, 1.5 mL, 2.0 mL and 2.5 mL of sodium chlorate standard solution (4.4) into the two-mouth flask. Respectively add 3.0 mL, 2.5 mL, 2.0 mL, 1.5 mL, 1.0 mL and 0.5 mL of water, then add 3.0 mL of sodium hydroxide solution (4.2). 6.1.2 Immerse the two-mouth flask in water bath at about 50 ???C for about 0.5 min, then, take it out. Quickly connect the separating funnel filled with 8.0 mL of hydrochloric acid (4.1) and 1.0 mL of o-tolidine indicating solution (4.5) to the two-mouth flask, tighten it to avoid air leakage. Place the two-mouth flask in tap water for rapid cooling, then, take it out. Firstly, add hydrochloric acid (4.1) into the two-mouth flask, mix it well, then, add o-tolidine indicating solution (4.5) into the two-mouth flask and shake it for 1 min; add 35 mL of water from the separating funnel. Transfer all the solution into a 100 mL volumetric flask; use water to dilute to the scale and shake it well.
6.1.3 Use water to adjust the zero point of the spectrophotometer; select a suitable cuvette. At a wavelength of 442 nm, determine the absorbance.
6.1.4 In accordance with 6.1.2 and 6.1.3, respectively determine other curve points. 6.1.5 Subtract the absorbance of the reagent blank from the absorbance of the colorimetric solution. Take the mass of sodium chlorate (???g) contained in 100 mL of colorimetric solution as the x-coordinate, and the corresponding absorbance as the y-coordinate to draw a standard curve.
6.2 Sample Solution
Weigh-take an appropriate amount of laboratory sample (accurate to 0.01 g) and prepare a certain volume of sample solution (no more than 33% based on NaOH), so that the amount of sodium chlorate does not exceed 12 mg/L.
6.3 Blank Test
Without adding test portion, add 3.0 mL of sodium hydroxide solution (4.2) and 3.0 mL of water. Adopt the same analytical procedures, reagents and dosages as the determination of the test portion to conduct the blank test.
6.4 Determination

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