Corrosion resistance analysis of 316L stainless steel needles used in vaccine packaging

The manufacturing and packaging of vaccines have become essential on the global stage due to the resurgence of the COVID-19 pandemic since 2020. The process of obtaining the vaccine ranges from laboratory studies to its storage in product reservoir tanks. To do so, the vaccine passes through filling pumps and sanitary hoses, until it is effectively filled into vials and ampoules using filling needles. However, they are developed in 316L stainless steel, which when exposed to stagnant or moving liquids can corrode and contaminate the drug. In this context, this work aims to evaluate whether there is chemical contamination of the needles supplied by the company Teksul Solu & ccedil;& otilde;es em Envase. To this end, 21 filling needles were immersed in excipients, with physicochemical properties that are equivalent to the vaccine, for 0, 35, 63 and 94 days. The excipients were evaluated for pH and atomic absorption, while the needles were evaluated by mass loss and gain analysis, microscopic analyzes obtained using SEM (Scanning Electron Microscope) and electrochemical corrosion tests. The results showed that increasing the immersion time of the filling needles favored the formation of a passive layer with corrosion resistance properties.