VOC’s and other contaminants have a nasty habit of being able to penetrate and be adsorbed by all manner of materials. They then “sit” in the pores and it’s your guess when they will be re-released. We call this the memory effect.
All the consumables supplied by Van Walt undergo rigorous QA and QC procedures and none more so than the 0.45 micron filter capsules used on site when collecting water samples for the analysis of metals.
These filters undergo very stringent tests with batch traceability and we need to protect them as well as possible but this can be difficult. Our supplier is in the United States and we make sure that we keep possible contamination routes as short as possible. So, for example, we air-freight. Expensive, but the route is kept short. And then there is the packaging. Filters come in boxes of 50 and to give added protection these are parcelled up. We do this by wrapping each box with standard kitchen foil to make an impenetrable barrier.
Easy, effective and cheap!