The University of Alaska Fairbanks participated in the Gas-Phase Sulfur Intercomparison Experiment (GASIE) to evaluate the sulfur chemiluminescence detector (SCD). The SCD is a relatively new sulfur selective detection technology (Benner and Stedman, 1989, 1990, 1994; Benner, 1991; Stedman and Benner, 1995). The system used during GASIE is referred to as the diffusion denuder/sulfur chemiluminescence detector (DD/SCD). We chose to use a diffusion denuder to separate SO2 from other sulfur species rather than a gas chromatograph because one of our long-term goals is to develop the DD/SCD into a unique system capable of resolving low pptv levels of SO2 on timescales of 1 min or less. The principles of detection of the DD/SCD and how it was operated during GASIE are presented. Results from the GASIE program are presented in detail by Stecher et al. (this issue). In this paper, we briefly describe what was learned about the diffusion DD/SCD technique from GASIE. To address the problems revealed, the DD/SCD has been completely redesigned and rigorously tested in our laboratory. The modifications made, how these modifications eliminate many of the problems found during GASIE, and results form subsequent laboratory testing are discussed.¿ 1997 American Geophysical Union