Temperature-induced changes in the sporicidal activity and chemical properties of glutaraldehyde

Freshly prepared 2% acid and alkaline glutaraldehyde solutions were stored at 4, 20, and 37 C. At intervals, samples were removed and changes in pH, ultraviolet spectrum, and sporicidal activity (against Bacillus pumilus spores) were recorded. Alkaline solutions stored at 4 C showed little changes in these properties, whereas such solutions stored at 37 C became turbid and showed a decrease in pH, marked changes in ultraviolet spectrum, and an almost complete loss of sporicidal activity. Intermediate results were obtained with alkaline solutions stored at 20 C. In contrast, acid 2% glutaraldehyde solutions (initial pH 3.5) showed comparatively few changes in their properties. Treatment of spores with freshly prepared glutaraldehyde solutions (0.5%) at temperature above 40 C reduced the effect of pH on sporicidal activity.