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SH/T 1499.7-2012 English PDF (SHT1499.7-2012)

SH/T 1499.7-2012 English PDF (SHT1499.7-2012)

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SH/T 1499.7-2012: Pure adipic acid. Part 7: Determination of content of nitric acid. Spectrophotometric method

This Part specifies the spectrophotometric method for the determination of nitric acid content in pure adipic acid. This Part applies to the determination of nitric acid content in pure adipic acid. The minimum concentration is 0.3 mg/kg.
SH/T 1499.7-2016
SH
PETROCHEMICAL INDUSTRY STANDARD
OF THE PEOPLE REPUBLIC OF CHINA
ICS 71.080.40
G 17
Filing No.. 36917-2012
Replacing SH/T 1499.7-1997
Pure adipic acid - Determination of content
of nitric acid - Spectrophotometric method
ISSUED ON. MAY 24, 2012
IMPLEMENTED ON. NOVEMBER 1, 2012
Issued by. Ministry of Industry and Information Technology of the People?€? Republic of China
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Method summary ... 5
4 Reagents and materials ... 6
5 Instruments ... 6
6 Sampling ... 7
7 Analysis steps ... 7
8 Calculation of results ... 8
9 Expression of analysis results ... 8
10 Repeatability ... 8
11 Report ... 8
Foreword
SH/T 1499 ?€?Pure adipic acid?€? is divided into the following parts.
- Part 1. Specification;
- Part 2. Determination of content - Titrimetric method;
- Part 3. Determination of chroma of ammonia solution - Spectrophotometric method; - Part 4. Determination of content of ash;
- Part 5. Determination of content of iron - 2, 2?€?-Bipyridyl spectrophotometric method; - Part 6. Determination of content of iron - Simple method;
- Part 7. Determination of content of nitric acid - Spectrophotometric method; - Part 8. Determination of content of oxidizable compounds -Titrimetric method; - Part 9. Measurement of melt colour (in Pt-Co scale);
- Part 10. Determination of content of moisture - Thermogravimetric method. This Part is Part 7 of SH/T 1499.
This Part is drafted according to the rules given in ISO/IEC 1.1-2009.
This Part replaces SH/T 1499.7-1997 ?€?Pure adipic acid - Determination of content of nitric acid - Spectrophotometric method?€?.
Compared with SH/T 1499.7-1997, the main changes of this Part are as follows. - MODIFY the standard name to ?€?Pure adipic acid - Determination of content of nitric acid - Spectrophotometric method?€?.
- ADD the reaction equation in the method summary.
- MODIFY the working curve range from 0 ??g ~ 50 ??g to 0 ??g ~ 25 ??g;
- MODIFY the mass of the sample from 2 g ~ 3 g to (2.0 ?? 0.1) g;
- MODIFY the solvent for dissolving the sample from water to ammonia;
- MODIFY the amount of urea added in the sample solution from 0.5 mL to 0.1 mL, and ALLOW cancelling the addition of urea when there is no nitrite ion in the sample;
Pure adipic acid - Determination of content
of nitric acid - Spectrophotometric method
1 Scope
This Part specifies the spectrophotometric method for the determination of nitric acid content in pure adipic acid.
This Part applies to the determination of nitric acid content in pure adipic acid. The minimum concentration is 0.3 mg/kg.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the dated edition cited applies. For undated references, the latest edition of the referenced document (including all amendments) applies.
GB/T 602-2002 Chemical reagent - Preparations of standard solutions for impurity GB/T 6678 General principles for sampling chemical products
GB/T 6679 General rules for sampling of solid chemical products
GB/T 6682 Water for laboratory use - Specifications
GB/T 8170 Rules of rounding off for numerical values & expression and judgement of limiting values
3 Method summary
Uranium salicylate reacts with nitric acid in nitric acid media, and the generated nitrides in alkaline medium is yellow. USE urea to eliminate the interference of nitrite; MEASURE the absorbance of the sample solution at the wavelength of 415; CALCULATE the mass fraction of nitric acid in the sample according to the work curve. (sodium salicylate)
(urea)
(sodium aminosalicylate)
6 Sampling
CARRY out according to the relevant specifications of GB/T 6678 and GB/T 6679. 7 Analysis steps
7.1 Work curve plotting
TAKE 6 clean and dry 50-mL volumetric flasks; ADD 0.00 mL, 0.05 mL, 0.10 mL, 0.15 mL, 0.20 mL and 0.25 mL of nitrate ion standard solution (4.7) and 2.00 mL ammonia solution (4.5) respectively. ADD 0.10 mL of urea solution (4.6) and 0.25 mL of sodium salicylate solution (4.4) respectively; SHAKE well; PLACE the volumetric flask into the (80 ?? 2) ??C water bath. After 5 min, REMOVE the first volumetric flask from the water bath and slowly add 4 mL of concentrated sulfuric acid (4.2); SHAKE continuously for 1 min; PLACE it on the laboratory bench. And then REMOVE the next volumetric flask, REPEAT the above operation. ADD 10 mL of hot water (about 50 ??C) to the volumetric flask respectively. After shaking well, slowly ADD 25 mL of sodium hydroxide solution (4.3) with the pipette (5.4); SHAKE well; COOL to room temperature. DILUTE to the mark with water; SHAKE well.
At the wavelength of 415 nm, taking the reagent blank as a reference, measure the absorbance of the standard solution.
The working curve is plotted with the mass (mg) of the sulfate ion as the ordinate and the absorbance as the abscissa, and the regression equation is obtained. 7.2 Sample measurement
WEIGH (2.0 ?? 0.1) g of sample, accurate to 1 mg; PLACE in a 50-mL clean and dry volumetric flask; ADD 2.00 mL of ammonia solution (4.5); shake well; ADD 0.1 mL of urea solution (4.6) and 0.25 mL of sodium salicylate solution; SHAKE well. PLACE the volumetric flask in a (80 ?? 2) ??C water bath; SHAKE until the sample is completely dissolved. After 5 min, REMOVE the volumetric flask from the water bath; slowly ADD 4 mL of concentrated sulfuric acid (4.2) to the volumetric flask; SHAKE continuously for 1 min. ADD 10 mL of hot water (about 50 ??C) to the volumetric flask. After shaking well, slowly ADD 25 mL of sodium hydroxide solution (4.3) with the pipette (5.4); SHAKE well. DILUTE with water to the mark; shake well. TAKE the reagent blank as a reference, MEASURE the absorbance at the wavelength of 415 nm. SUBSTITUTE the measured absorbance into the regression equation to obtain the mass (??g) of the nitrate ion.
NOTE 1. If it is determined that no nitrite ions are present in the sample, the addition of urea can be canceled in operations of 7.1 and 7.2.

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