Unless otherwise specified, oligonucleotides are shipped in a dried form. It may be difficult to see the oligo at the bottom of the vial as it may be present as a thin film or a miniscule pellet. To ensure that no product is lost upon opening, briefly spin down the vial in a bench top microcentrifuge before removing the cap. Once suspended in buffer, checking the OD at 260 nm will verify the oligo’s presence and concentration.