Endotoxin adheres to plastic surfaces more strongly than to glass surfaces. Therefore, we recommend that you use only borosilicate glass dilution tubes when preparing your Control Standard Endotoxin (CSE) dilutions. In some cases, certain plastics may prove to be acceptable sample containers. While glass is still the preferred sample container material, polystyrene may be a good second choice, and polypropylene a third option. Some customers also report good results using PET. If you plan to store your sample for any period of time prior to testing, you should validate sample storage in the type of container you plan to use and verify that any endotoxin present in the sample will be recoverable after storage.