8. Procedure
8.1 Switch on the titrimeter and allow the electrical circuits to stabilize in accordance with the manufacturer's instructions.
8.2 Cool the titration vessel to 0 to 5°C (32 to 41°F) by circulating a suitable coolant through the jacketed titration vessel.
8.3 Introduce 110 mL of titration solvent into the titration vessel and pipet in a quantity of sample as indicated in Table 1. Switch on the stirrer and adjust to a rapid stirring rate, but avoid any tendency for air bubbles to be drawn down into the solution. Allow the contents to cool to 0 to 5°C (32 to 41°F) and maintain at this temperature throughout the titration. (Warning - Hydrocarbon samples, particularly those boiling below 205°C (400°F), are flammable.)
8.3.1 Frequently the order of magnitude of the bromine index of a sample is unknown. In this case, a trial test is recommended using an 8 to 10-g sample in order to obtain the approximate magnitude of the bromine index. This exploratory test should be followed with another determination using the appropriate sample size as indicated in Table 1.
8.3.2 The sample mass can be determined by obtaining the density of the sample and calculating the mass of a measured volume.
8.4 Set the end point potential. With each instrument, the manufacturer's instructions should be followed for end point setting and to achieve the sensitivity in the platinum electrode circuit specified in 6.1.
8.5 Depending on the titrator apparatus, add the bromide-bromate solution manually or by microprocessor control in small increments from the buret. The end point of the titration is achieved when the potential reaches the pre-set value (see 8.4) and persists for more than 30 s.
8.6 Blanks - Make duplicate blank titrations on each batch of titration solvent and reagents. Less than 0.10 mL of bromide-bromate solution should be required.