Some standard content:
National Standard of the People's Republic of China
Working chemical
Benzoic acid
GB 12597—90
This reagent is a flake or needle-shaped crystal, which can sublimate, is difficult to dissolve in water, and is easily soluble in organic solvents such as ethanol and ether. Indicative formula: C.HsCOOH
Relative molecular weight: 122.12 (according to the international atomic weight in 1987) Subject content and scope of application
This standard specifies the technical requirements, test methods, inspection rules, packaging and marking of the working standard reagent (volume) benzoic acid. This standard is applicable to the test of working standard reagent (volume) benzoic acid with a content of 99.95% to 100.05%. 2 Reference standards
GB6682
Chemical reagents
Chemical reagents
Chemical reagents
Chemical reagents
Chemical reagents
Chemical reagents
Chemical reagents
Preparation of standard solutions for titration analysis (volume analysis) Preparation of standard solutions for impurity determination
Preparation of preparations and products used in test methods General method for determination of melting point range
Sampling and acceptance rules
Specifications for water for laboratories
GB 9728
GB9729
GB9739
GB 9741
GB 10737
Chemical reagents
General method for determination of sulfate
Chemical reagents
Chemical reagents
Chemical reagents
General method for determination of chloride
General method for determination of iron
General method for determination of residue on ignition
General rule for weighing working standard reagents (capacity) potentiometric titration method HG 3—119
Chemical reagent packaging and marking
HG 3—1168
Chemical reagents
3 Technical requirements
Preparation and determination of clarity standards
3.1 Benzoic acid (CH4;C00H) content, %: 99.95~100.05. 3.2 Melting point range, ℃: 121.5~123.5. 3.3 Maximum impurity content, %:
Approved by the State Administration of Technical Supervision on December 18, 1990 and implemented on December 1, 1991
Clarity test, No.
Ignition residue (calculated as sulfate)
Chlorine compounds (C12)
Sulfur compounds (calculated as SO4)
Iron (Fe))
Heavy metals (calculated as Pb （measured in units of ）
Substances that reduce potassium permanganate (measured in units of ○)
Easily carbonizable substancesWww.bzxZ.net
4 Test method
GB 12597-90
Working standard (capacity)
The standard solution for titration analysis, standard solution for impurity determination and the preparations and products used in this test method shall be prepared in accordance with the provisions of GB601, GB602 and GB603. The water used in the experiment shall comply with the third-grade water specifications in GB6682. 4.1 Determination of benzoic acid (CgH, COOH) content 4.1.1 Calibration of the concentration of the standard solution for sodium hydroxide titration analysis Weigh 0.5g of the first reference reagent (volume) potassium hydrogen phthalate dried to constant weight at 105-110℃, accurate to 0.00001g, place it in a reaction bottle, dissolve it in 30mL of carbon dioxide-free water, add 4mL of 95% ethanol, and pass high-purity nitrogen gas into the solution from the branch pipe for 10min under stirring. Adjust the intake volume of the nitrogen inlet pipe to maintain a small nitrogen flow. Use a 231-type glass electrode as the indicator electrode and a 232-type saturated calomel electrode as the reference electrode. According to the provisions of GB10737, titrate to the endpoint with the sodium hydroxide to be calibrated for titration analysis (c (NaOH) - 0.1mol/kg). Perform a blank test at the same time. The concentration of the standard solution for sodium hydroxide titration analysis is calculated according to formula (1): my
C (m2-ms)× 0.204 21
Wherein: ℃
0.204 21-
the concentration of the standard solution for sodium hydroxide titration analysis, mol/kg; the mass of the first reference reagent (capacity) potassium hydrogen phthalate, mmol/kg; the mass of the standard solution for sodium hydroxide titration analysis to be calibrated, mmol/kg; the mass of the standard solution for sodium hydroxide titration analysis to be calibrated used in the blank test, 8; (1)
the mass of potassium hydrogen phthalate expressed in grams equivalent to 1.000 0g of the standard solution for sodium hydroxide titration analysis [C(NaOH)-1.0000mol/kg].
Note: ① Before substituting ml, m2, and ms into the formula (1), buoyancy correction should be performed according to the provisions of Appendix B (Supplement) of GB10737. ② The density of potassium hydrogen phthalate is 1.63 g/cm. 4.1.2 Determination of content
Weigh 0.3 g of the sample dried to constant weight in a phosphorus pentoxide desiccator, accurate to 0.00001 mol, place it in a reaction bottle, dissolve it in 4 mL of 95% ethanol, add 30 mL of carbon dioxide-free water, and pass high-purity fluorine gas into the solution from the branch pipe for 10 minutes under stirring. Adjust the intake volume of the nitrogen inlet pipe to maintain a small nitrogen flow. Use a 231-type glass electrode as the indicator electrode and a 232-type saturated calomel electrode as the reference electrode. According to the provisions of GB10737, titrate with sodium hydroxide to the end point with the standard solution [c (NaOH) - 0.1 mol/kg]. At the same time, perform a self-test.
The electrodes used for the determination of the content and the calibration of the concentration of the standard solution for sodium hydroxide titration analysis are the same set of electrodes. The content of benzoic acid (C.HsCOOH) is calculated according to formula (2): X = (m - ms)e × 0. 122 12 × 100m6
Wherein: x
the percentage of benzoic acid, %;
GB 12597--- 90
the mass of the standard solution for sodium hydroxide titration analysis, 8; the mass of the standard solution for sodium hydroxide titration analysis used in the blank test, name, C-the concentration of the standard solution for sodium hydroxide titration analysis, mol/kg; 0. 122 12-
the mass of benzoic acid in grams equivalent to 1.0000g of the standard solution for sodium hydroxide titration analysis c (NaOH) = 1.0000mol/kg);
m. the mass of the sample, .。
Note: (i) Before ml, m5 and ms in formula (2) are substituted into the formula, buoyancy correction shall be performed according to the provisions of Appendix B (Supplement) of GB10737. ② The density of benzoic acid is 1.27 g/cm.
4.2 Melting point range determination
Determine in accordance with the provisions of GB617.
4.3 Impurity determination
The sample shall be weighed accurately to 0.01 g.
4.3.1 Clarity test
Weigh 10 g of sample and dissolve it in 80 mL of water and 20 mL of ammonia water. The turbidity shall not be greater than the clarity standard No. 2 specified in HG3--1168.
4.3.2 Ignition residue
Weigh 10 g of sample and determine and calculate in accordance with the provisions of Articles 4.1 and 5 of GB9741. Keep the residue for the determination of iron. 4.3.3 Chlorine compounds
Weigh 1g of sample, place in platinum, add 5mL of sodium carbonate solution (50g/L), mix well, evaporate to dryness on a water bath, heat to carbonize, gradually heat to 700C and burn to white, cool, dissolve in hot water (filter if necessary), neutralize with nitric acid solution (25%), dilute to 20mL, and measure according to the provisions of GB9729. The turbidity shall not be greater than the standard. The standard is to take a standard solution for impurity determination containing 0.03mg of chloride (CI) and treat it in the same way as the sample. 4.3.4 Sulfur compounds
Weigh 2g of sample, place in a platinum crucible, add 10mL of sodium carbonate solution (50g/L), mix well, evaporate to dryness on a water bath, heat to carbonize, gradually heat to 700C and burn to white, cool, dissolve in hot water (filter if necessary), add 1mL of 30% hydrogen peroxide, boil to decompose hydrogen peroxide, neutralize with hydrochloric acid solution (20%), and add 0.5mL in excess, boil again, cool, dilute to 20mL, and measure according to the provisions of GB9728. The turbidity shall not be greater than the standard.
The standard is to take a standard solution for impurity determination containing 0.06mg of sulfate (SO), and treat it in the same way as the sample. 4.3.5 Iron
Add 3mL hydrochloric acid and 1mL nitric acid to the residue after the ignition residue is determined, dissolve it, evaporate it on a water bath, add 0.2mL hydrochloric acid and a small amount of water, dissolve it in warm water, dilute it to 50mL, take 5mL, dilute it to 15mL, and adjust the pH value of the solution to 2 with ammonia solution (10%).According to the provisions of GB9739, the red color should not be darker than the standard. The standard is to take a standard solution for impurity determination containing 0.004mg iron (Fe), add 0.1mL hydrochloric acid solution (10%), dilute to 15mL, and treat it in the same way as the sample solution of the same volume. 4.3.6 Heavy Metals
Weigh 2g of sample, add 20mL of water, add ammonia solution (10%) until the sample is dissolved, dilute to 45mL, add 2mL of thioacetamide solution (50g/L) and 2mL of sodium hydroxide solution (10g/L), shake well, and let it stand for 10min. The dark color should not be darker than the standard. The standard is to take a standard solution for impurity determination containing 0.01mg lead (Pb), dilute to 45mL, and treat it in the same way as the sample solution of the same volume.
4.3.7 Potassium permanganate reduction substances
Weigh 1g of sample, add 100mL of water, heat to dissolve, add 20mL of sulfuric acid solution (20%) and 0.1mL of potassium permanganate titration analysis standard solution (
=KMno,)=0.1mol/L), shake well, the red color should not disappear completely. 661
4.3.8 Easily carbonizable substances
GB12597—90
Weigh 0.1g of sample, place in a dry colorimetric tube, add 2mL of sulfuric acid, stir and dissolve in a 50℃ water bath, and keep for 5min. Compared with the blank, no dark color should be produced.
5 Inspection rules
Sampling and acceptance shall be carried out in accordance with the provisions of GB619. 6
Packaging and marking
According to the provisions of HG3-119, among which:
Inner packaging form: G-2;
Outer packaging form: Made of 600g/m2 boxboard paper, with purple electro-optical paper on the outer layer; Packing unit: Class 3.
Additional instructions:
This standard is proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of Beijing Chemical Reagent General Factory. This standard is drafted by Beijing Chemical Factory. The main drafters of this standard are Wang Sunchu, Liu Dongni and Chen Hua. 662
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.