WARNING: This protocol involves chlorine gas and should only be performed by professional researchers with biosafety training in a laboratory environment. DO NOT ATTEMPT WITHOUT PROPER TRAINING AND EQUIPMENT. 

This protocol uses chlorine gas to surface sterilize Arabidopsis thaliana seeds.  This is for when you want to perform a more thorough sterilization than an ethanol wash.

The original protocol is attributed to Maud Hinchee (Monsanto), Steven Clough (UI-Urbana-Champaign), and Andrew Bent (UI-Urbana-Champaign).

Wear gloves and use proper ventilation. 

1. Make sure the microcentrifuge tubes your seeds are in are properly labeled.  Pencil and paper works the best as chlorine gas can sometimes wipe sharpie clean off of a surface.
2. Place your tubes inside a container that can be closed with a lid.
3. Place that container inside a fume hood.
4. Make sure the tubes are open.  Centrifuge tube lids off.   
5. Place a 250 mL beaker inside the container with the tubes.
6. Put 100 mL of bleach in the beaker.
7. Pipette 3 mL of concentrated HCl into the bleach.
8. Immediately seal the lid of the container after this addition.
9. Let the seeds sit for 3-5 hours.
10. Dispose of all waste material properly.