Abstract
This sensitive, albeit precarious, method for measuring ppb-ppt (V/V) concentrations of H2S was examined for various sources of potential error within the procedure. Filter preparation, filter storage, filter extraction, fluorimetric reagent stabilities, matrix differences between standards and samples, and possible interferences from other sulfur-containing compounds were separately studied for their effects on the analytical performance of the method. The overall method showed no Interference from SO2, CS2, COS, CH3SH, CH3SCH3, and SO4 -2. To minimize bias and obtain a reliable estimate of precision, the method should be calibrated with H2S standards rather than liquid bisulfide standards. The measurement precision is a function of the quantity of H2S collected as Ag2S and/or AgSH on the impregnated filters. Because of the method’s linear dynamic range, sufficient air should be sampled to achieve filter loadings of 15 to 35 ng S/filter. A quality control method based on fluorescein mercuric acetate (FMA) is presented that ensures data quality while reducing the otherwise frequent need for fluori-metric calibration.