Table 2. Longest Time before any Detectable PenG Degradation in a Solution under Different pH Values and Temperatures^a.

temp.	pH 2.0	pH 2.5	pH 3.0	pH 4.0	pH 5.0	pH 7.0
4 °C	2 min	15 min	1 h	1 h	1 h	1 h
12 °C	2 min	2 min	4 min	1 h	1 h	1 h

^aMaximum of 60 min assay.