TOTAL INHIBITOR CONTENT OF LIGHT HYDROCARBONS: ASTM D1157
EXPLANATION
p-tertiary-butyl catechol (TBC) is commonly added to commercial butadiene in amounts of 50 to 250 mg/kg as an oxidation inhibitor. This test method is suitable for use by both producers and users of butadiene. In general, all phenols and their quinone oxidation products are included in the calculated catechol content. Small amounts of polymer do not interfere. The test method is applicable over the range of TBC from 50 to 500 mg/kg.
TEST SUMMARY
The catechol is separated from the butadiene by evaporation. The residue is dissolved in water and an excess of ferric chloride is added. The intensity of the yellow-colored complex is compared in a photoelectric colorimeter with that produced by known concentrations of catechol.
TEST PRECISION
In the TBC concentration range of 50 to 500 mg/kg, this test method has a repeatability of 10 and a reproducibility of 20.
The bias of this test method has not been determined.
