FY 1988

Electron capture sulfur detector: Reduced sulfur species detection at the femtomole level

Johnson, J.E., and J.E. Lovelock

Anal. Chem., 60(8), 812–816, doi: 10.1021/ac00159a016 (1988)

We have developed a new technique to detect reduced sulfur compounds by fluorination with F₂ (at 200 ppm) on a heated Ag catalyst after GC separation. The excess F₂ is removed by conversion to HF by reaction with H₂ on a heated Pd catalyst. The fluorination product, presumably SF₆, is then detected in an electron capture detector (ECD). The Pd catalyst also destroys the response from halocarbons making the system sulfur specific. This ECD sulfur detector has a calculated minimum detectable level (MDL) for H₂S, OCS, CH₃SH, DMS, and CS₂ of less than 2 fmol/s for each compound, 2 orders of magnitude lower than the best FPD systems. The ratio of the detected molar response of each of these sulfur compounds to the molar response of SF₆ ranges from 2% to 20% and increases with increasing AgF₂ temperature.