The bromine indicates the amount of unsaturated bonds in petroleum product components. It is defined as the number of milligrams of bromine consumed by 100 g of sample.
The sample is dissolved in a solvent and reacted by changing bromine ions to bromine through electrolytic oxidization. In coulometric titration, the amount of reacted bromine is determined from the amount of electricity (coulombs) required for this electrolytic oxidization.
Reagents
Anolyte: A solution consisting of a mixture of 600 mL of acetic acid, 260 mL of methanol, and 140 mL of 1 mol / L potassium bromide solution.
Catholyte: 0.2 mol/L potassium chloride aqueous solution Test solution: 0.051 wt% solution which diluted cyclohexene with toluene as a trial sample.
Equipment
Karl Fischer moisture titrator for coulometric method
Sample Preparation
1) Fill the titration flask with approximately 100 mL of anolyte.
2) The test solution is injected 20 to 100 μL by a syringe, then perform preliminary titration.
Measurement
1) Collect a sample using a syringe and measure the mass.
2) Inject the sample from the syringe inlet of the titration cell and measure.
3) Measure the syringe mass after sample injection.
4) The difference in the mass of the syringe before and after injection of the sample is used as the sample collection volume.
