Bromine index determination standard substance (Bromine index standard sample, Bromine index standard substance, Bromine index standard substance)

Bromine Index Determination Standard Material (Bromine Index Standard Sample Bromine Index Standard Material Bromine Index Standard)

Brand: Petrochemical Science Research Institute

Selling point and application: Produced by the Institute of Petrochemical Science, used for the determination of bromine index in petrochemical products by Coulomb method

Description: [Bromine Index Standard Substance] The following concentrations are optional: 10, 57, 114, 460 mgBr/100g

【 Storage conditions 】 Keep away from light

Standard substance for bromine index determination

(Bromine Index Standard Sample/Bromine Index Standard Material/Bromine Index Standard)

1. Product Overview

The standard substance for bromine index determination is a chemical reference substance that has been rigorously certified and has known accurate bromine index values. It is mainly used for calibrating analytical instruments, validating analytical methods (such as ASTM D2710, GB/T 11136, etc.), conducting laboratory quality control, and capability verification.

The bromine index is an important indicator for measuring the content of unsaturated hydrocarbons (mainly olefins) in petroleum products (such as gasoline, kerosene, alkanes, alkenes), organic solvents, and chemical raw materials. It is defined as the milligrams of bromine that reacts with 100 grams of sample under specific conditions. The higher the bromine index value, the higher the content of brominated (usually unsaturated) compounds in the sample.

2. Core purpose and importance

Instrument calibration and calibration: used to calibrate bromine index measuring instruments such as automatic potentiometric titrators and coulometric titrators to ensure accurate measurement.

Method validation: To validate the accuracy and precision of a newly established or commonly used bromine index determination method.

Quality control: The laboratory regularly uses standard substances for internal quality inspections and monitors the stability of the testing process.

Capability verification and arbitration analysis: as an objective benchmark for inter laboratory comparisons or dispute arbitration.

3. Typical product characteristics

Matrix (solvent): usually a stable hydrocarbon or aromatic solvent, such as isooctane, toluene, n-hexane, etc., with an extremely low background bromine index.

Standard substance type:

Single component standard sample: prepared by dissolving a known concentration of pure olefin (such as 1-hexene, cyclohexene) in an inert solvent, with clear theoretical values.

Simulated sample standard: Simulate the unsaturated hydrocarbon composition of actual samples (such as specific gasoline fractions), which is more representative.

Certification value (bromine index value): Provide a bromine index standard value accurate to a certain decimal point (unit: mg Br/100g), accompanied by uncertainty (usually expressed as expanded uncertainty, k=2).

Fixed value method: The laboratory collaboratively determines the value through two or more independent and accurate analytical methods (such as precision coulomb method, gas chromatography method).

Physical form: Liquid, packaged in ampoules or brown glass bottles to prevent changes in content caused by light exposure and volatilization.

4. Key technical parameters (taking actual product certificates as an example)

Project Description

Standard substance name: Bromine index standard substance in iso octane

Bromine index standard value, for example: 100.5 mg Br/100g

Extended uncertainty (k=2), for example: ± 2.1 mg Br/100g

Matrix solvent isooctane (chromatographically pure)

Characteristic component 1-hexene (or mixed olefin)

Fixed value method, precision coulometric titration, gas chromatography

Packaging specifications: 2mL ampoule or 20mL brown glass bottle

Storage conditions: Keep away from light, at low temperatures (such as 4 ℃ refrigeration or -18 ℃ freezing), and sealed. It is recommended to use it once after opening the bottle.

The validity period is usually 6 months to 2 years, as specified in the certificate.

5. Main brands and suppliers

Metrology Institute: Certified Reference Materials (CRMs) provided by the Chinese Institute of Metrology (NIM), the National Institute of Standards and Technology (NIST), and others have the highest quality.

Professional standard product manufacturers, such as AccuStandard, ChemService, LGC Standards, Tianjin Alta Technology, etc., provide a wide variety of commercial standard products.

Self supplied by petrochemical enterprises: Large enterprise laboratories may also prepare working level standards according to internal needs, but CRM is required for traceability.

6. Precautions for use

Traceability and certification: When purchasing, the "Certificate of Reference Materials" should be requested and properly stored, which is the basis for its traceability, validity, and legality of measurement values.

Proper storage: Store strictly according to the certificate requirements. Incorrect storage (especially under light and high temperature) can lead to olefin polymerization or reaction, rendering the standard values invalid.

Balance before use: After being taken out of a low-temperature environment, it should be balanced at room temperature until it is clear and uniform before use.

Avoid contamination: Use dry and clean containers when sampling to prevent the introduction of moisture and impurities.

Disposable: For ampoule standard samples, it is recommended to use them all at once. Bottled samples should be used as soon as possible after opening and resealed for refrigeration.

7. Selection suggestions

Quantity matching: Select standard substances with bromine index values close to the range of daily test samples, usually recommended to cover low, medium, and high points.

Uncertainty requirement: Select products with appropriate uncertainty levels based on their own quality control requirements. The uncertainty at the level of metrology institute is the smallest, and the price is also higher.

Matrix matching: Choose standard substances that are as similar or identical as possible to the matrix of the test sample to reduce errors caused by matrix effects.

Qualification and traceability: Confirm the qualifications of suppliers to ensure that standard substances can be traced back to national or international standards.