How to prepare and ship a peptide sample without ruining the result

Water uptake is the first. A freeze-dried cake is porous and hygroscopic by construction, which is what makes it reconstitute quickly and also what makes it equilibrate with atmospheric moisture almost immediately on exposure. Powder decanted into a plastic bag arrives heavier than it left, and net peptide content, milligrams per vial and any assay derived from mass all report low by however much water was absorbed. The laboratory can measure the water and say so, but it cannot recover the original figure.

Contamination in transit is the second. Once a container has been opened, a microbial count describes the handling as much as the product, and there is no analytical way to separate the two afterwards. This is why unopened units are a requirement rather than a preference for enumeration and sterility work.

Rigid outer packaging with individual wrapping. Glass that arrives broken cannot be analysed and cannot be replaced by the laboratory. Loose vials in a padded envelope arrive broken often enough to be worth stating.

Do not decant. Transferring a lyophilisate into a different vial introduces water, loses material on the walls, and destroys any statement about seal integrity, which is itself recorded on receipt.

Where cold chain matters, say so in the enquiry rather than assuming it. A solution that spent a week at ambient temperature will show degradation products, and that result describes the shipping rather than the product.

Compound, or unknown if a blind determination is wanted. Matrix and dosage form. Declared amount as printed. Batch or lot number. The determinations wanted, or the question that needs answering. How many units are available and whether they come from one batch. The country the shipment leaves from.

Customs declarations and import lawfulness rest with the sender. A laboratory cannot advise on them and cannot accept a shipment a carrier or authority refuses.