Container Closure Integrity Testing (CCIT) is an assay that evaluates the adequacy of container closure systems to maintain a sterile barrier against potential contaminants. Contaminants that could potentially cross a container closure barrier include microorganisms, reactive gases, and other substances (USP <1207>). Container closure systems should maintain the sterility and product quality of sterile final pharmaceutical, biological, and vaccine products throughout their shelf-life. Container closure systems consist of primary packaging components and secondary packaging components (USP <1207>). Primary packaging components are those components that come into direct contact with the product, such as a glass vial or syringe. While, secondary packaging components are those components that are vital to ensure correct package assembly, such as aluminum caps over stoppers (USP <1207>). Container closure integrity testing can be performed in many different ways. All of the testing methods have pros and cons. In addition, some containers, such as ampoules, require 100% integrity testing. Contract Container Integrity Testing laboratories offer numerous state- of-the-art options for leak testing and assessing pharmaceutical package integrity per USP <1207>. Container Closure Integrity test programs have been successfully used to optimize sealing parameters, evaluate container storage temperature impact, replace sterility tests for product stability batches, screen production lots for faulty packages and support regulatory submission applications for product commercialization around the world. Helium mass spectrometry is most suited for non-porous packaging such as vials, syringes, and cartridges. However, even flexible packaging can be tested by helium mass spectrometry using appropriate test fixture and techniques. Helium-filled or flushed samples are placed in a test chamber, where a vacuum is created by the instrument’s internal pumps. In certain circumstances, specialized fixtures may be created to isolate particular package areas of interest. Leaking samples allow helium to escape, enter the test system, and be detected by an analyzer cell. The stream of helium ions hitting the analyzer cell target is proportional to the partial pressure inside a sample. From this, a specific leak rate can be calculated and reported to the user. Results can be reported quantitatively (as a leak rate), or qualitatively (Pass or Fail) if method development is performed. This type of testing may be of interest to clients looking to accurately assess the performance of an established package or analyze the effect of processing variables, such as capping force, closure materials, etc., on the performance of a package system. Analytical service providers conduct electrical conductivity / high voltage leak detection (HVLD) testing on a range of package systems, including parenteral vials, prefilled cartridges and syringes, plastic containers and plastic bags or pouches.