The most commonly used technique to detect sulfur in petroleum samples utilizes a Dry Colorimetric Detector ("tape" technology) . The organically bound sulfur is first converted to H2S. The H2S formed reacts with the moist paper tape impregnated with lead acetate. An "electronic eye" detects the change in color of the tape as H2S passes by the tape and forms black lead acetate. The chemical reaction on the tape surface is:

The lead acetate detection method is the only detection system that can determine H2S without any interference. This fact is clearly stipulated in ASTM method. This is an important feature in a detector when one is detecting very low levels of sulfur in a complex hydrocarbon matrix.

There are two ways to convert organically bound sulfur to H2S. The first technique is to use reductive pyrolysis. The organically bound sulfur is mixed with excess of hydrogen and passed through a high temperature ceramic tube held at 1200ºC. The sulfur combines with hydrogen to form H2S while the hydrocarbons are reduced to methane gas. The lead acetate tape detects the H2S.

The second technique for this conversion requires, first, oxidative pyrolysis, and then, reductive pyrolysis. This technique is used to solve the coking problem. A sample containing sulfur compounds and hydrocarbons is blended with air at 1200ºC. The sulfur compounds are oxidized to SO2 and SO3 and the hydrocarbons to CO2 and H2O. In the second zone, a flow stream of hydrogen then reduces the oxides of sulfur to H2S. The water and carbon dioxide formed as by-products interfere with the tape detector and must be removed.

Dry Colorimetric Detection technique's strength is that it is based on simple chemistry, and there are no known interferences. Both Chemiluminescence and Pulsed uV Fluorescence suffer interference from hydrocarbons, requiring GC separations and/or an extremely efficient high temperature reactor to make clean combustion.