If the material is stored refrigerated, you should let the container warm to room temperature before sampling. A cold, dry powder will adsorb moisture very fast. The container must be tightly sealed to prevent exposure to atmospheric moisture. Solvents such as anhydrous methanol and DMSO and hygroscopic materials may need to sampled in a dry box. If this is not possible, you might want to consider sending the sample to us in an unopened, original bottle.
Deviations can only lead to problems.