To preserve and prevent segregation of the contents.
Explorer Packs comprise the CRM in a wet strength geochem envelope vacuum sealed in barrier foil.These are little packets. Plastic by itself will cause segregation of our powder through the buildup of an accumulated electrostatic charge, especially in arid atmospheres. Vacuum sealing in foil turns the contents of the pouch into a solid little brick, preventing product segregation and oxidation. Putting the CRM into a geochem envelope as well affords the opportunity to place the sample into a sample stream with no need for repackaging (if you are using the same geochem envelopes for your sample pulps).
Laboratory Packs comprise 1000g of CRM in a 2 litre container, sealed in foil with an O-Buster©. When packaged into tubs the product is certified homogeneous. They are what are sampled. During storage and transport there will be segregation within the container. Using a 2 litre container affords plenty of space to shake up the contents before use. We can’t vacuum seal the Lab Pack tubs. We seal them in a foil pouch and put in an O-Busters© instead. O-Busters© are a clever little product that can pick up approximately three times its weight in oxygen. They are widely used in packaging perishables, helping to eliminate the need for gas flushing and vacuum packing