in the equilibrium headspace of residual fuel oils, specifically ASTM D396 Grades 4, 5, and 6, with viscosities ranging from 5.5 at 40°C to 50

is the standard test method for the field measurement of hydrogen sulfide ( H2Scap H sub 2 cap S

: The sample is purged with nitrogen and heated to 60°C while being agitated, often at 220 RPM.