Figure 1.

A: Chromatogram of a sample obtained at time 0 and stored for 85 days at −85°C shows vancomycin peak at 1.57 min and internal standard (metronidazole) peak at 2.59 min. B: Chromatogram of a sample obtained on day 75 of storage at room temperature and then stored for 10 days at −85°C shows an additional small degradation peak at 1.35 min. C: Chromatogram of vancomycin solution (in water) after degradation with 1N sodium hydroxide and boiling for 10 minutes shows 2 noninterfering peaks at 1.04 min and 1.38 min and a 93% reduction in the vancomycin peak. D: Chromatogram of vancomycin solution (in Ora-Sweet vehicle and water) after degradation by incubation at 100°C for 18 h shows 4 noninterfering peaks at 1.00, 1.48, 1.75, and 1.89 min and a 58% reduction in the vancomycin peak. AU = absorbance units.