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IP 30: Detection of mercaptans, hydrogen sulfide, elemental sulfur and peroxides - Doctor test method
- Method adopted/last revised: 2021
- Method reapproved: None
- REF/ISBN: IP030-2936900
- Status: Current
- First printed in STM books: April 2007
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Scope
The Standard describes the 'Doctor' test for detecting the presence of mercaptans (thiols), hydrogen sulfide, elemental sulfur and traces of peroxides, see note 1, in automotive fuels, kerosines, and other middle distillate petroleum products.
NOTE 1 - The presence of a number of substances in the test sample can affect the result of the test.
Peroxides
This method cannot be used if there are more than trace amounts of peroxides in the test sample.
Carbon disulfide
If the test sample contains more than 0,4% (m/m) of sulfur as carbon disulfide it causes a darkening of the aqueous layer on standing and caution is necessary to avoid confusing this darkening with the immediate blackening due to hydrogen sulfide or that produced by mercaptans.
Phenolic substances
Certain phenolic substances (which may have been introduced as inhibitors) cause colouration of the aqueous layer and if their presence is suspected, a blank test with sodium hydroxide solution in place of the sodium plumbite solution should be carried out first for the purpose of comparison, see 6.1.
Scope
The Standard describes the 'Doctor' test for detecting the presence of mercaptans (thiols), hydrogen sulfide, elemental sulfur and traces of peroxides, see note 1, in automotive fuels, kerosines, and other middle distillate petroleum products.
NOTE 1 - The presence of a number of substances in the test sample can affect the result of the test.
Peroxides
This method cannot be used if there are more than trace amounts of peroxides in the test sample.
Carbon disulfide
If the test sample contains more than 0,4% (m/m) of sulfur as carbon disulfide it causes a darkening of the aqueous layer on standing and caution is necessary to avoid confusing this darkening with the immediate blackening due to hydrogen sulfide or that produced by mercaptans.
Phenolic substances
Certain phenolic substances (which may have been introduced as inhibitors) cause colouration of the aqueous layer and if their presence is suspected, a blank test with sodium hydroxide solution in place of the sodium plumbite solution should be carried out first for the purpose of comparison, see 6.1.
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