The Ames miniscreen assay: volatility of sodium azide can cause an increase in the reversion frequencies of adjacent, untreated wells.
Sodium azide, when added to wells adjacent to untreated wells, caused an increase in the reversion rate of Salmonella typhimurium TA100 in a 12-well plate format. Increases in the reversion frequency in adjacent, untreated wells were observed when a single well on the plate was treated with as little as 1 microg of sodium azide. This effect is probably caused by the hydrolysis of sodium azide to form hydrazoic acid. Hydrazoic acid has a boiling point of 37 degrees C and, thus, would become a diffusible gas during the incubation of the plates. Our findings suggest that a diffusible gas is present and that this gas has the ability to contaminate nearby wells when using the multiwell version of the Ames assay. Furthermore, it may be prudent to isolate all positive controls and negative controls on separate plates with no test material since a volatile test material could produce spurious results in the Ames miniscreen.
Wilson
J D
JD
Medicine Safety Evaluation, Glaxo Wellcome Inc., Research Triangle Park, North Carolina 27709, USA.
Cariello
N F
NF
D001386:Azides; D009152:Mutagenicity Tests / Q000379:methods*; D012486:Salmonella typhimurium; D019810:Sodium Azide
D001386:Azides; D019810:Sodium Azide