<organic mercaptans (the stuff they use to odorize natural gas with>

I worked at a small gas plant years ago as a roustabout and we would empty 55g drums of mercaptan into the propane loading station. If you stood downwind when the drum was pouring into the vessel, you would smell like that crap for about a week. Nasty stuff!
I have two test kits, one reads in ppb and the other in ppm. I dont know if most people are worried about the dissolved O2 content in their tanks but they are **** good test kits, easy to use and pretty reasonably priced compared to all the other test kits out there and very accurate.