With the SS mFPD optimized, efforts were made to better characterize its analytical performance attributes. Fig 4 illustrates the typical results with a calibration plot for tetrahydrothiophene response as a function of analyte quantity in the S2* operating mode. As seen, sulfur response in the SS mFPD increases over about 4 orders of magnitude. Further, the slope of this response is nearly quadratic for higher analyte amounts (10−9–10−7 orange)and reduced at lower concentrations (below 10−9), which is commonly observed for S2* emission in a conventional FPD