Our patented O.E.S. (Optical Emission Spectroscopy) method does not require any specific tracer gas. Instead, the gas mixture present in the container headspace of the primary packaging is used to perform high sensitivity tests with high throughput. A multi-gas sensor is used to independently track the different gases (i.e. argon, nitrogen, CO2, humidity,…) escaping from a leaky container exposed to vacuum. Our method is non-destructive, deterministic, easy to use and to set up, faster and has higher sensitivity than other conventional methods. O.E.S. is able to detect down to 0.2µm defect size on glass containers which corresponds to the sterility barrier defined as the MALL (Maximum Allowable Leak Limit) in the USP<1207> guidelines.