Laboratory validation and field verification of a new passive colorimetric air monitoring badge for sampling hydrogen sulfide in air.

The Pro-Tek passive colorimetric air monitoring badge for personal or area sampling of hydrogen sulfide is described. The badge has been validated over the range of 1.8 to 164 ppm-hours (0.23-21 ppm on an 8-hour TWA basis). It has an overall accuracy throughout this range of +/- 15.9% and meets the NIOSH accuracy criteria for an analytical and sampling method. The colorimetric analytical method used is based on the Texas Air Control Board's Molybdenum Blue method. Color-activated exposed badge solutions are read out on a standard laboratory spectrophotometer using 1 centimeter (10 mm) cells. Variations in exposure temperature (between 10 degrees and 40 degrees C), relative humidity, and face velocity (between 2 and 250 ft/min) do not affect badge performance. Unexposed badges are stable for more than 12 months refrigerated and for two months at room temperature.