ASTM D5808 Organic Chloride in Aromatic Hydrocarbons and Related Chemicals
ASTM D5808 Standard Test Method for Determining Organic Chloride in Aromatic Hydrocarbons and Related Chemicals by Microcoulometry
4. Summary of Test Method
4.1 A liquid specimen is injected into a combustion tube maintained at 900°C having a flowing stream of oxygen and argon carrier gas. Oxidative pyrolysis converts the organic halides to hydrogen halides that then flow into a titration cell where it reacts with silver ions present in the electrolyte. The silver ion thus consumed is coulometrically replaced and the total electrical work to replace it is a measure of the organic halides in the specimen injected (see Annex A1).
5. Significance and Use
5.1 Organic as well as inorganic chlorine compounds can prove harmful to equipment and reactions in processes involving hydrocarbons.
5.2 Maximum chloride levels are often specified for process streams and for hydrocarbon products.
5.3 Organic chloride species are potentially damaging to refinery processes. Hydrochloric acid can be produced in hydrotreating or reforming reactors and this acid accumulates in condensing regions of the refinery.
6. Interferences
6.1 Both nitrogen and sulfur interfere at concentrations greater than approximately 0.1 %.
NOTE 1 - To ensure reliable detectability, all sources of chloride contamination must be eliminated.
6.2 Bromides and iodides, if present, will be calculated as chlorides. However, fluorides are not detected by this test method.
6.3 Organic chloride values of samples containing inorganic chlorides will be biased high due to partial recovery of inorganic species during combustion. Interference from inorganic species can be reduced by water washing the sample before analysis. This does not apply to water soluble samples.
