If a membrane adsorber is not the right fit — because the elution peak is too broad, because the chemistry you need is not offered, or because pleat-to-pleat flow distribution limits your resolution — the closest alternative in the same speed class is a monolith. Both are convective media: the liquid carries the target past the ligand instead of the target diffusing into a particle. MonoCore™ is a cross-linked cellulose monolith available as Q and S (strong and weak ion exchange), HIC (butyl and phenyl), Protein A and Protein G, with a 15 µm channel size, in 1.8 mL and 5.4 mL capsules with UNF 10-32 connectors for standard FPLC systems.
The three media classes, honestly
Packed-bed resin. Transport is by diffusion into the bead. Capacity for proteins is high, capacity for large particles such as viruses or plasmid DNA is low, because the particle does not enter the pores. Speed is limited by pressure and bed compression. Resolution is high, void volume low, and the choice of chemistry is the widest of the three. It is supplied as a column to be packed.
Membrane adsorber. Transport is convective, through the membrane. Capacity for proteins is lower, for large particles good. Speed is high. Resolution is lower because of pleat-to-pleat heterogeneity, and void volume is higher. The choice of chemistry per supplier is narrower. It is supplied as a disposable capsule.
Monolith. Transport is convective, through the channels. Capacity for proteins is medium to high, for large particles good. Speed is high. Resolution is resin-class, void volume low, and the choice of chemistry is broad. It is supplied as a ready-to-use capsule.
Read that in both directions. Membrane adsorbers are the better answer where a fully disposable flow-through step at low cost per run is the goal, or where the step is a polish that does not need resolution. Packed-bed resins remain the better answer where capacity per millilitre decides the economics and time is not the constraint. A monolith is the better answer where you want membrane-class speed without giving up peak shape: one continuous flow path instead of a stack of layers, so flow distribution is more uniform, void volume smaller and the eluate less diluted.
What changes in practice
Peak shape and dilution. A narrower elution peak means a more concentrated product and less buffer downstream. That is the most visible difference between a monolith and a pleated membrane stack.
Chemistry choice. Ion exchange in strong and weak form, hydrophobic interaction with butyl and phenyl ligands, affinity with Protein A or Protein G — on one backbone.
Blocking behaviour. A 15 µm channel is an order of magnitude wider than the pore size of a typical adsorptive membrane. With a complex feed, this is what decides how soon the pressure starts to climb.
The equipment stays. UNF 10-32 connectors, standard FPLC system, no re-skidding.
Where MonoCore™ does not help
Written down deliberately, because it saves both sides a call.
Capacity per millilitre against a modern Protein A resin. If your process is capacity-bound rather than time-bound, a resin remains the economical choice.
Sharper peaks than a packed bed. A monolith is resin-class in resolution. We do not claim better.
Very large volumes today. Standard formats are 1.8 mL and 5.4 mL; larger sizes are built on request rather than taken off a shelf.
Full disposability at the lowest cost per run. A single-use membrane capsule is hard to beat there.
The MonoCore™ family
MonoCore™ Q — strong and weak anion exchange; capture and polishing, viral vectors and nucleic acids.
MonoCore™ S — strong and weak cation exchange; polishing of antibodies and antibody formats.
MonoCore™ HIC — hydrophobic interaction with butyl and phenyl ligands; aggregate and monomer separation.
MonoCore™ Protein A — affinity capture for IgG and Fc-bearing formats.
MonoCore™ Protein G — affinity capture with broad IgG subclass and species coverage.
All on the same cellulose backbone, 15 µm standard channel size, 1.8 mL and 5.4 mL, larger on request. Detailed performance data are available on request.
Frequently asked questions
Is a monolith a membrane?
No. A membrane adsorber is a stack of thin adsorptive layers; a monolith is one continuous porous body with through-going channels. Both transport by convection, but the flow path differs — and with it flow distribution, void volume and peak shape.
Why do monolith suppliers quote a channel size while membranes quote a pore size?
Because what is measured differs. In a monolith the number describes the diameter of the through-going flow channels; in a membrane it describes the pores in the layer. A channel is not a dead-end pore in a particle, which is why the term matters.
Is 15 µm not very large?
It is deliberately large. The channel carries the flow, and the adsorptive surface sits on the channel wall. A wider channel means lower pressure drop and greater tolerance for complex feeds. The trade-off is surface area per millilitre, which is why channel size is chosen per application — 15 µm as standard, other sizes on request.
Which suppliers of monoliths exist?
Polymer monoliths are the established class. Lumatix builds monoliths on a cross-linked cellulose backbone, which brings a hydrophilic surface with low non-specific adsorption. There are newer entrants in the field as well; the media classes differ more from each other than the suppliers within a class.
Can I run a monolith on my existing system?
Yes. The capsules ship pre-assembled with UNF 10-32 coned ports for 1/16″ tubing and connect to a standard FPLC system, a peristaltic pump or a syringe.