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Ficoll is a trademarked name from Cytiva, and in the laboratory it usually points to Ficoll-Paque, a ready-to-use density gradient medium built on Ficoll PM400 and sodium diatrizoate. The standard grade, Ficoll-Paque PLUS, is supplied at a density of 1.077 g/mL and is used to separate mononuclear cells from human peripheral blood by centrifugation. It is a separation medium, not a stain, a buffer or a culture reagent.
Definition and scope
The names Ficoll, Ficoll-Paque, Percoll and Sepax are trademarks of Cytiva, so “Ficoll” in a protocol or purchase request can mean more than one product. Two meanings matter in practice:
- Ficoll PM400 is the Ficoll component of the medium. Cytiva lists it as a separate product sold in 100 g, 500 g and 5 kg sizes.
- Ficoll-Paque is the finished medium for density gradient centrifugation. According to the Cytiva data file (CY13571, 2020), Ficoll-Paque PLUS “consists of a mixture of Ficoll PM400 and sodium diatrizoate at a density of 1.077 g/mL” and is sterile and ready to use.
When a lab method says “layer over Ficoll”, it almost always means a Ficoll-Paque type medium at a stated density. For the full workflow that uses it, see our guide to PBMC preparation for flow cytometry; this page covers the medium itself.
How it is used in practice
Density gradient centrifugation separates cells by buoyant density. Cytiva describes Ficoll-Paque PLUS as developed for large- or small-scale purification of mononuclear cells from human peripheral blood using the Böyum technique (Böyum 1968, Scandinavian Journal of Clinical and Laboratory Investigation 21:77-89). The same data file states that the medium can be adapted to other sources, including abdominal, amniotic and pleural fluids and bone marrow. The centrifuge, rotor and brake settings belong to your method; our guide to what a centrifuge is covers the instrument side.
Cytiva reports the following typical results for the recommended protocol on normal human peripheral blood. These are vendor-stated figures, not guarantees for your samples:
| Measure | Vendor-stated typical value |
|---|---|
| Lymphocyte recovery | 60% ± 20% |
| Mononuclear cells in the harvested layer | 95% ± 5% |
| Viability | >90% |
| Granulocytes | 3% ± 2% |
| Red blood cells | 5% ± 2% |
| Platelets remaining | <0.5% of the original |
Ficoll-Paque grades and Percoll compared
Cytiva lists Ficoll-Paque PREMIUM at two other densities, 1.073 and 1.084 g/mL, alongside the 1.077 g/mL PLUS grade. It also lists Percoll and Percoll PLUS as an alternative family. The comparison below uses only figures from the Ficoll-Paque PLUS data file and the Cytiva cell separation media handbook.
| Ficoll-Paque PLUS | Percoll PLUS | |
|---|---|---|
| Composition | Ficoll PM400 and sodium diatrizoate | Silane-coated, silica-based colloidal medium |
| Supplied density | 1.077 ± 0.001 g/mL | 1.130 ± 0.005 g/mL |
| Gradient | Ready-made single density layer | Adjusted to iso-osmotic gradients of 1.0-1.3 g/mL |
| Endotoxin specification | <0.12 EU/mL | <2 EU/mL |
The handbook notes that Percoll forms its own gradient during centrifugation (at about 10,000 × g or more in 0.15 M NaCl with an angle rotor), which is a different mechanism from layering a ready-made Ficoll-Paque medium. The Ficoll-Paque PLUS data file adds that PLUS and Percoll have been used in combination to isolate defined subpopulations.
Where it matters for labs and supply decisions
Because “Ficoll” covers several products, a purchasing or inventory record should capture the details the data file itself specifies. This checklist is taken directly from the Ficoll-Paque PLUS specifications:
- Grade and density: PLUS at 1.077 ± 0.001 g/mL, or PREMIUM at 1.073 or 1.084 g/mL.
- Endotoxin: specification below 0.12 EU/mL for PLUS (see LAL endotoxin testing for how such values are measured).
- Sterility: sterilised by autoclave steam to a sterility assurance level of 10-6 (see sterility assurance level).
- Storage and shelf life: stable for 3 years when stored at 4-30 °C protected from direct light.
- Pack format: ready-to-use medium versus Ficoll PM400 raw polymer (100 g, 500 g, 5 kg).
Cells isolated this way often go on to freezing or culture; see cryopreservation of cells and aseptic technique for those steps.
Common misunderstandings
“Ficoll” and “Ficoll-Paque” are the same thing
They are not. Ficoll PM400 is a component; Ficoll-Paque is the finished, sterile, density-adjusted medium that also contains sodium diatrizoate.
Every Ficoll-based medium works at 1.077 g/mL
The 1.077 g/mL value is the specification of the PLUS grade, which Cytiva developed for human peripheral blood mononuclear cells. PREMIUM is offered at 1.073 and 1.084 g/mL, so the density in a protocol should match the grade in the lab.
Ficoll-Paque and Percoll are interchangeable
They differ in composition, supplied density, preparation and endotoxin specification, as the table above shows.
Vendor recovery figures apply to any sample
The recovery and viability numbers are typical values for normal human peripheral blood under the recommended protocol, as stated by the vendor.
Frequently asked questions
What is Ficoll used for?
Ficoll-Paque is used for density gradient centrifugation to purify mononuclear cells from human peripheral blood, and with adaptation from some other fluids and bone marrow, per the Cytiva data file.
What is in Ficoll-Paque PLUS?
A mixture of Ficoll PM400 and sodium diatrizoate in an aqueous, sterile, ready-to-use medium at 1.077 g/mL.
How long does Ficoll-Paque PLUS keep?
The data file gives a stability of 3 years when stored at 4-30 °C, protected from direct light.
Is Ficoll the same as Percoll?
No. Per the Cytiva documents, Ficoll-Paque PLUS combines Ficoll PM400 with sodium diatrizoate at 1.077 g/mL, while Percoll PLUS is a silane-coated, silica-based colloidal medium supplied at 1.130 g/mL; see the comparison table above.
Sources
- Cytiva, Ficoll-Paque PLUS data file (CY13571-22Jul20-DF), https://cdn.cytivalifesciences.com/api/public/content/digi-14502-pdf, checked 2026-10-29.
- Cytiva, Cell separation media: methodology and applications (Percoll handbook), https://cdn.cytivalifesciences.com/api/public/content/digi-12439-pdf, checked 2026-10-29.
- Böyum A. Isolation of mononuclear cells and granulocytes from human blood. Scand J Clin Lab Invest 1968;21:77-89 (as cited in the Cytiva data file).
