To ensure patient safety, good container closure integrity (CCI) is of great importance for all sterile injectable products. Recent regulatory guidance has made clear that there is no ‘gold standard’ for CCI testing. As a CCI test method, headspace analysis is based on detecting changes in the headspace gas composition that result from gas ingress through a leak. Non-destructive headspace analysis, using laser-based spectroscopy, can be used to directly quantify the gas concentration inside a sealed parenteral package. It can be applied to a range of product configurations, and formulations, and has historically been used for detecting leak defects in modified headspace product.