Oxygen Measurement in Packaging
The acceptable oxygen level within packaging can vary significantly depending on the product. Certain goods, such as foods, pharmaceuticals, and technical applications, are sensitive to oxygen and require suitable packaging materials for protection.
It is crucial to assess the barrier properties of packaging and synthetic materials and the oxygen content within the final packaged product to ensure product safety and extend its shelf life.
The diverse range of packaging materials poses different requirements for sensors used in quality checks or oxygen transmission rate (OTR) measurements.
Conventional Clark-type oxygen sensors are often too large for such applications. They require an opening in the packaging wall or a special lid to accommodate the sensor, and significant efforts must be made to prevent atmospheric oxygen from entering the packaging and distorting the measurements. Additionally, these sensors consume oxygen during the measurement process.
Optical Oxygen Sensors
Optical oxygen sensors offer a solution to overcome these drawbacks. They come in various designs and can be used for quality assessments during production and filling processes and for testing the leak tightness of packaging and material properties. Optical measurement systems enable the determination of oxygen ingress in packaging under realistic conditions, such as carbonised liquids or under pressure.
Non-invasive oxygen measurements can be performed in transparent or slightly coloured containers using optical oxygen sensor spots. These small sensors (Ø 5 mm), approved for use with food products, allow contactless oxygen read-out. The sensor spots are attached to the inside wall of the container, below the filling level or in the headspace area.
After filling and sealing the container, the oxygen content inside the product and the headspace can be easily determined by placing a polymer optical fibre connected to the oxygen meter against the outside wall opposite the sensor spot. This technique has been applied to analyse the oxygen content in glass beverage bottles with different closures, such as crown caps and swing stoppers. However, oxygen dissolves in the product during filling and can also migrate out of or permeate through the packaging material. Oxygen sensor spots have been utilised to study the oxygen barrier properties of variously treated PET bottles.
Needle-type Oxygen Microsensors
Needle-type oxygen microsensors can be employed for non-transparent containers or measurements in small volumes, such as pharmaceutical packaging. These sensors, housed in a syringe needle, allow piercing of the packaging material and determining the oxygen content in the gas or liquid inside the container. A septum is attached to the packaging to prevent oxygen from entering when piercing through the wall. Optical oxygen microsensors offer fast response times, and stable measurement values can be obtained within seconds.
Their sensor tips have diameters as small as 50 µm, enabling oxygen measurement in minute volumes, such as blister packaging or the headspace of pharmaceutical vials. Since the microsensors do not consume oxygen during the measurement process, precise results can be obtained even in volumes as small as a few mL.
Summary
Optical oxygen sensors are available for measurements in different oxygen ranges, including normal range (detection limit of 15 ppb dissolved oxygen, 0 - 100% O2), trace range (detection limit of 1 ppb dissolved oxygen, 0 - 4.2% O2), and ultra-trace range (detection limit of 0.5 ppmv O2, 0 - 200 ppmv O2 in gases). This versatility makes optical sensors an ideal tool for determining the barrier properties of synthetic materials.
PVL Oxygen Sensor
The ResOx 5695-L is an oxygen measuring system designed for convenient use in assessing the quality of MAP food packaging and similar tasks. It includes a gas pump and is fully prepared for immediate use.
This system is specifically designed to provide accurate measurements, even for rigid packages, thanks to its pressure compensation feature. It is also equipped with a membrane filter that effectively prevents the unintentional suction of particles or liquid.
With its battery-powered functionality and waterproof design, this device offers great versatility and user-friendliness.
Contact Us
Pressure Vacuum Level Ltd has been selling high-quality oxygen sensors for several years. PVL provides these devices for various industries.
Don't hesitate to contact us if you have any questions about our oxygen sensors or other products by emailing sales@pvl.co.uk or calling +44 (0) 1892 66 44 99
