Cryovials are screw-capped polypropylene tubes designed to hold biological samples at temperatures down to –196 °C. To store them safely, choose a size and thread that suit the application, use labels rated for liquid nitrogen, and keep every vial in a recorded box and rack position in the vapour phase of a cryogenic tank.
These sound like small decisions. In practice they decide whether a sample is still intact, readable and easy to find ten years from now. A label that peels off, a cap that leaks or a position nobody wrote down can make perfectly cryopreserved cells useless. This guide covers what labs, biobanks and GMP manufacturers should check when they select, label and store cryovials.
Cryovials differ by nominal volume, thread type, base and material. The common sizes are:
Pay attention to the working volume. Manufacturers state a maximum fill below the nominal volume, and the headspace absorbs expansion during freezing so the cap stays tight. A 2 ml cryovial is never filled to the brim.
For GMP and clinical work, add further requirements: sterile, free of DNase, RNase and pyrogens, with a certificate per lot and a documented supply chain. The vial is part of the primary container and needs to be qualified like any other.
The thread affects both handling and contamination risk:
Both designs seal with a silicone gasket or a moulded sealing lip. Use caps and tubes from the same manufacturer and close them to the specified torque. A cap that is overtightened can leak at –196 °C just like one that is too loose, because polypropylene and gasket contract at different rates.
Self-standing vials with a star-shaped base make bench work easier, and 2D barcodes on the base let a reader scan a whole rack of vials without taking each one out.
A sample with an unreadable label is lost, even if the cells inside are fine. Ordinary lab labels and marker pens do not survive cryogenic storage: adhesives turn brittle, labels lift during thawing, and ink smears in ethanol or when frost is wiped off.
What works:
ISO 20387 requires biobanks to keep every sample traceable throughout its life cycle, and cell and tissue therapy programmes widely use ISBT 128 for labelling. For the freezing step that comes before storage, follow our step-by-step cryopreservation protocol for cells.
Standard cryovials belong in the vapour phase. Most manufacturers state that their vials are not designed for immersion in liquid nitrogen, and the reason is a safety one.
Liquid nitrogen can seep into a vial through tiny leaks. When the vial is taken out and warms up, the trapped nitrogen boils off and expands to roughly 700 times its liquid volume. The vial can burst and scatter fragments and sample material. Immersion also creates a cross-contamination path through the liquid itself.
If liquid-phase storage is unavoidable, heat-seal vials in a sleeve approved for it and wear a face shield and cryogenic gloves when retrieving them. For most applications vapour-phase storage is now the norm: a well-designed tank keeps it far below the glass transition of water at about –135 °C. Our comparison of vapour-phase vs. liquid-phase cryogenic storage covers the trade-offs in detail.
Vapour-phase temperature is not uniform. It is coldest just above the liquid and warmest near the lid, which leads to three simple rules:
A temperature mapping study confirms which positions stay within limits. When moving racks, keep boxes out of the tank for as short a time as possible and work on pre-cooled carriers. A few minutes at room temperature can warm a cryovial above –135 °C.
Cryovials do not sit loose in a tank. They stand in cryo boxes, which are stacked in racks or cassettes. Common grids are:
Polycarbonate or polypropylene boxes with a numbered grid lid and drainage holes are built for cryogenic use; cardboard boxes soften with frost and condensation. Box height has to match vial length, or the lid presses on the caps.
How many boxes fit in a tank depends on the rack. A rack system matched to the tank's inner diameter and storage height uses the space far better than a generic rack that leaves gaps. Our guide to maximising cryogenic storage capacity with racks, cassettes and boxes shows how to plan it.
It depends on the tank, the vial size and the rack system. Datasheet figures for 2 ml vials in the Consarctic® BSF+ and BSR+ series give a reference point:
The turntable versions hold slightly fewer vials but make every position far easier to reach: instead of leaning over the tank, the user rotates the required rack under the opening. That shortens lid-open time and protects the samples that stay inside.
Consarctic® is a market-leading German manufacturer of cryogenic systems for the life sciences. Tanks, racks, cassettes and monitoring are designed as one system, which for cryovials means:
Consarctic® is certified to ISO 9001:2015 and EN ISO 13485:2016 and serves more than 1,500 customers in over 30 countries, including Qatar Biobank, the Finnish Red Cross and Charité Universitätsmedizin Berlin.
Standard cryovials are meant for the vapour phase. In the liquid phase, nitrogen can leak in and make the vial burst as it warms. If liquid-phase storage is required, heat-seal the vials in an approved protective sleeve and always wear a face shield when removing them.
Polyester or polypropylene cryogenic labels with an adhesive rated for liquid nitrogen, printed by thermal transfer. Apply them to clean, dry vials at room temperature before freezing. Combine a 2D barcode with a human-readable ID.
It depends on the model. According to the datasheets, a Consarctic® BSF220+ holds 10,400 2 ml vials, a BSF420+ 25,900 and a BSF820R+ 48,000. Vial size, box grid and a rack system matched to the tank decide the final number.
Only up to the working volume stated by the manufacturer, which is below the nominal volume. The headspace takes up expansion during freezing; an overfilled vial can leak or loosen its cap.
Cryovials are the smallest link in the cold chain and often the most overlooked. Choosing the right size, thread, label and storage position protects every sample for years and keeps it easy to find.
Do your racks, boxes and vials really fit your tanks? Talk to the experts at Consarctic®. We plan cryogenic storage from the single vial to the complete cryostore.