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Oxygen Ingress Measurement into PET Bottles using Optical-Chemical Sensor Technology
Huber, Ch., Nguyen, T.-A., Krause, Ch., Humele, H., Stangelmayer, A.

A new non-invasive and non-destructive fibre optic oxygen meter determines oxygen permeability of plastic bottles and containers via measuring trace concentrations of oxygen inside the package. Ideal for assurance, production and quality control applications, this system incorporates the latest state-of-the-art in optical-chemical sensor technology. Permeation rates can be confirmed without piercing the package or bottle. Oxygen ingress or seal integrity can be verified as it occurs in normal packaging processes. The sensing principle is based on a fluorescence quenching method enabling oxygen measurements in a non-destructive way. A trace oxygen sensor spot is placed on the inner wall of the transparent bottle or package and a fibre optic cable is positioned on the outside. The luminescence lifetime of the oxygen-sensitive spot changes with the oxygen concentration and is therefore acting as the oxygen dependent parameter. This internally referenced parameter is detected by the oxygen meter avoiding common problems provided by intensity based measurements. This measurement technique enables long-term studies with low amount of samples and highly reliable data. Concentration levels of gaseous or dissolved oxygen can be detected in parts per million to parts per billion ranges. Measurement results of oxygen ingress into several different treated PET bottles are presented using the novel technology. The PET bottles differ from its barrier coatings (internal and external), multi-layer design and inclusion of different amount of oxygen scavenger materials.

Descriptors: Oxygen permeation, oxygen measurement, PET bottles

BrewingScience - Monatsschrift fr Brauwissenschaft, 59 (November/December 2006), pp. 5-15