Method Comparison Study-One Step Forward toward Robust Silicone Layer Thickness Measurements.

In the past decades, the silicone layer thickness and its distribution on the inner glass barrels of prefilled syringes have been characterized in several studies. However, the limited number of adequate methods to characterize thin baked-on silicone layers and the destructive nature of some analytical techniques suggest challenges to the inter-lab reproducibility of some methods. In this study, the measured silicone layer thickness of baked-on siliconized syringes was compared between two laboratories, both equipped with white light reflectometry coupled to laser interferometry instrumentation (Bouncer, LE UT 1.0, LE UT 2.0). The quantity of silicone oil of a subset of those syringes was measured by Fourier transform infrared spectroscopy. Glide force tests were realized as complementary measurements on both syringes analyzed by white light reflectometry coupled to laser interferometry instrumentation and on non-analyzed identical syringes from the same lot. Silicone profiles of all prefilled syringes including the limit of detection results replaced with 20 nm were comparable, but values were slightly lower when measured with the Bouncer instrument. An increase of the layer thickness from the finger flange to the needle side was found for all syringes with all instruments (20 nm to 130-140 nm). Glide force results were similar except for a difference in peak width in the break loose region between the laboratories. The mean quantities of silicone oil found by both laboratories were similar (64 µg/syringe and 69 µg/syringe). Overall, comparable results between laboratories suggest a good reproducibility of the thickness measurement method as a result of thorough method understanding and defining key method parameters. Hence this study presents a robust inter-lab comparison between silicone layer thickness measurements that has been a lack in the literature up to now.

Investigating the Effects of the Chemical Composition on Glass Corrosion: A Case Study for Type I Vials.

Glass is the favorite material for parenteral packaging because of its physico-chemical properties. Type I borosilicate glass is worldwide use at this scope, but it may have some issues related to breakage, corrosion and delamination that might compromise the drug quality, safety and efficacy. These issues can be mitigated and avoided starting from the appropriate selection of the most suitable raw material at the early stage of the glass container design. In this study, Type I borosilicate glass vials manufactured using two glass tubes having different chemical compositions, were studied and compared in terms of their resistance to corrosion. Testing design was applied with the aim to select the best practice approach comparing different storage simulation conditions: ageing treatment through autoclaving and stability testing (real-time and accelerated). Clear differences were found between the different glass types in terms of hydrolytic and corrosion resistance that highlighted the relation between chemical composition and glass chemical durability. Non-negligible differences were also observed using different storage conditions.

Laser ablation-ICP-MS depth profiling to study ancient glass surface degradation.

In general the analysis of archeological glass represents a challenge for a wide variety of objects because of the presence of physical and/or chemical damage on the surface of the artifact, also known as weathering or corrosion. To retrieve accurate bulk elemental information by laser ablation-inductively coupled plasma-mass spectrometry (ICP-MS), the original, pristine glass needs to be "reached", thereby penetrating the alteration layer which is often more than 10 µm thick. To study this alteration layer the laser was operated in the drilling mode, either with a low (1 Hz) or a high (10 Hz) pulse repetition rate for a period of 50 s yielding detailed spatial information for ca. 20 elements over a shallow depth (ca. 5 µm) or less-detailed spatial information for 50-60 elements over a greater depth (ca. 50 µm). Quantitative elemental depth profiles (in wt%) were obtained with the so-called sum normalization calibration protocol, based on summation of the elements as their oxides to 100 wt%. We were able to associate the increase of SiO2 (in wt%) in the alteration layer to the volumetric mass density change in the glass as a result of depletion of Na2O and K2O. Also the interaction of the number of laser shots with the alteration layer is shown experimentally via depth measurements using profilometry. Chemical and physical changes in four ancient glass artifacts, directly and indirectly measureable by laser drilling, were studied as a function of internal and external factors such as age, composition, and exposure conditions.