Volatile. Flammable. Skin irritant. Respiratory irritant. Possibly fatal if swallowed. For those of you processing samples according to EPA Method 1664B, you’ve seen these hazard descriptions before – on the safety data sheet (SDS) for n-hexane. For those of you who aren’t familiar with (or have forgotten about) the hazards related to n-hexane, those are just a few. It also smells unpleasant and could explode if heated. It’s a relatively unpleasant organic solvent to work with and it begs the question:
On the surface, EPA Method 1664B seems pretty straightforward – use n-hexane to extract compounds (commonly referred to as “oil and grease”) from an acidified water sample. Evaporate the hexane from the extract, weigh the residue that gets left behind, and report that weight in terms of a concentration (often as mg/L of HEM).