Unless our client requires exact weights (e.g. determined by phosphorus analysis for an additional charge) or you have purchased a specially pre-packaged product, we over-pack our catalog products up to 10% (especially when dealing small unit sizes < 100 mg). For example, the concentration on the vial is correct (e.g. 5 mg/mL, 10 mg/mL, etc.), however you will receive a volume greater than required (e.g. for 1 ml solution perhaps 1.1 to 1.3 mL ).
Weights are determined by either physically weighing out (powders) or from measured aliquots from a gravimetrically determined solution typically within 10%. Weights on saturated or non-hygroscopic lipids are determined by physically weighing the product. For mono unsaturated or hygroscopic lipids, aliquots are measured from gravimetrically determined solutions packaged, and then lyophilized (e.g. from cyclohexane) to a powder. Note: Poly-unsaturated lipids are not shipped as powders. The packaging of powders is product dependent and may be shipped in sealed ampoules, in white screw cap vials or brown screw cap bottles.