ESCA depth profiling studies of borosilicate glass containers.
This article discusses the results of studies that utilized Electron Spectroscopy for Chemical Analysis (ESCA), a surface analytical technique, in conjunction with Ar+ ion milling, a method of depth profiling, to examine some borosilicate glass containers. The ESCA depth profiling experiments involved several elemental analyses (Na, Ba, O, B, Si, Al, and C) for both the product-contact surface and various depths (0.01-0.30 micron) beneath the surface. Untreated vials, (NH4)2SO4 treated vials, and (NH4)2SO4 treated ampoules were analyzed in this study. The experiments included both unprocessed and processed containers as well as vials and ampoules that were exposed to various aqueous media (H2O, pH = 8 buffer, and pH = 10 buffer) for congruent to 6 months at room temperature. Assuming the samples were representative of most (NH4)2SO4 treated and untreated containers, the results indicate that ESCA depth profiling studies can distinguish an (NH4)2SO4 treated container from an untreated one for unprocessed and processed containers as well as containers that are exposed to aqueous media. In general, treated samples were unaffected by processing and long-term, room-temperature exposure to H2O or a pH = 8 buffer. In contrast, washing and sterilizing operations led to significant changes in the surface and near near surface composition of untreated containers, and six-month, room-temperature exposure to H2O or a pH = 8 buffer resulted in some additional changes. Also, the data indicated glass dissolution had occurred for both treated and untreated containers that had been processed and exposed to pH = 10 media. Finally, the results suggested that significant differences in the surface/near surface composition can lead to significant differences in the extractable behavior of borosilicate glass containers.