uV Fluorescence has been used in detection of SO₂ in stacks and air monitoring for many years. The adoption of this detector for detection of total sulfur measurements in hydrocarbons is very recent.

This "new" method has achieved both ASTM and EPA approvals. In spite of the approvals, however, this method has not proven itself in total sulfur measurements in the field.  There is known interference from water and hydrocarbons.  The key factor in making an analyzer using a uVF detector is the design of the pyrolysis system.  The conversion process must ensure complete conversions; otherwise, false results and a fouled-up detector due to incomplete combustion products (black soot) will cause major concern.

C.I.'s three-zone pyrolysis is used to convert sulfur-containing molecules to SO₂. This conversion technique is simple, yet very important for long-term detection of sulfur in samples like diesel and kerosene. The Dynamic Combustion Technique, developed and used only by C.I., is required to ensure that there will be no interference from hydrocarbons.

uVF detection of sulfur occurs as follows:

• Sulfur-containing molecules in the sample stream are oxidized to SO₂ using the three-zone combustion technique.

• The SO₂ formed, is excited with a specific wavelength of uV light.

• Excited SO₂ decays, emitting a second, specific wavelength of light.

• This light is detected by a photomultiplier tube through an optical filter. SO₂ is a very stable molecule, making this method robust.

C.I. offers uVF detection if the customer application is suitable for this technology. Sometimes, the customer prefers this technology to other techniques, and C.I. is then in a position to offer this technique.