The Incident
To a reaction mixture were added several bottles of borane dimethyl sulphide complex. As the contents of one bottle were added, the colour darkened rapidly and a vigorous reaction started. The sash was quickly lowered as the vessel contents were ejected, and the laboratory evacuated. The spill team, wearing full BA, dealt with the cleaning up.
The Investigation
It was apparent that the last bottle to be added was at fault. Checking the remaining contents found that the bottle had been filled with bleach. Closer examination found that the back of the bottle was poorly marked with "bleach for decon". No adulteration had been made of the label.
Conclusions
- In error a bottle of bleach was added to the mixture, which already contained a significant amount of borane dimethyl sulphide complex
- The bottle had obviously been used in the past and had been filled with a bleach solution to destroy the residual dimethyl sulphide.
- Although the bottle was marked with a felt tip pen (amber bottle), no attempt was made to black out / remove the original label.
Lessons Learnt
The practice of destroying the trace amounts of dimethyl sulphide was a good one. However the failure to remove (or even deface) the original label was the root cause of the problem.