Milligram and microgram quantities of product may be difficult to visualize within the vial, especially oils, films, and dense liquids or solids. Additionally, transit may disperse the material throughout the inner surface of the vial rather than in a distinct pellet or pool. Centrifuging or shaking down the sealed vial with a flick of the wrist may bring the material to the bottom of the vial. If you still have questions regarding the expected appearance of your product, please contact our Technical Support scientists. Including a photograph of the vial is immensely helpful for comparison to vials in stock.