Euglobulin precipitation, ion-exchange, and size-exclusion chromatography polishing — a dedicated workflow for IgM, the immunoglobulin class Protein A and Protein G cannot reliably capture.
IgM purification is the process of isolating IgM-class immunoglobulins from a crude biological source — hybridoma culture supernatant, ascites fluid, or serum — into a high-purity, low-aggregate reagent suitable for IVD raw material use. IgM is structurally distinct from the more commonly purified IgG: rather than the single ~150 kDa Y-shaped IgG monomer, native IgM circulates as a pentamer (or, in some species and secretory contexts, a hexamer) with a molecular weight of approximately 970 kDa, joined by a J-chain.
This structural difference has a direct practical consequence: Protein A and Protein G — the affinity ligands behind fast, single-step IgG purification — do not reliably bind IgM. Protein A's binding site targets IgG-specific Fc structural features that most IgM subclasses do not present, and Protein G does not bind IgM at all. IgM purification therefore requires an entirely different toolkit, built around IgM's physical rather than immunochemical properties:
For IVD developers building IgM-specific assays — most often early-window infectious disease serology, where IgM appears before IgG in the immune response — sourcing correctly purified, low-aggregate IgM is a common bottleneck. Sekbio's IgM purification service is built specifically to close that gap.
IgM's size, solubility profile, and aggregation tendency demand a purification strategy built around its physical chemistry, not a repurposed IgG protocol.
The first-stage workhorse of Sekbio's IgM workflow: low-ionic-strength, low-temperature precipitation concentrates IgM away from the bulk of serum albumin and IgG before chromatography begins.
Sequential ion-exchange and size-exclusion chromatography remove residual contaminants and resolve monomeric pentameric IgM from both small impurities and high-molecular-weight aggregates.
Because IgM self-associates more readily than IgG at high concentration, every batch is characterized by SEC-HPLC against a tighter aggregate specification than typical IgG release criteria.
Purification from hybridoma supernatant, ascites, or serum, scalable from milligram R&D quantities to multi-gram OEM batches under ISO 13485-certified manufacturing.
For IgG-class antibody expression and purification support, explore our full antibody development platform.
The same antibody purification goal — high purity, low aggregate, ready for IVD use — but a structurally different starting point demands a different method.
| Parameter | IgG (Protein A) | IgM (Sekbio Workflow) |
|---|---|---|
| Native Structure | Monomer, ~150 kDa | Pentamer (J-chain linked), ~970 kDa |
| Primary Capture Method | Protein A affinity chromatography | Euglobulin cold precipitation |
| Polishing Method | Ion-exchange (optional) | Ion-exchange + size-exclusion (required) |
| Typical Process Time | 1 step, same-day capture | Multi-step, precipitation + 2-stage chromatography |
| Aggregation Risk | Low | Moderate — requires SEC polishing & tighter QC |
Need residual Protein A detected or removed from an IgG purification workflow? See our Chicken Anti-Protein A Antibody for Protein A interference removal and QC.
A complete IgM purification workflow from crude source material to a characterized, ready-to-use reagent.
Every IgM purification batch is released against purity, aggregate content, and recovery yield specifications before delivery, with a Certificate of Analysis documenting SDS-PAGE and SEC-HPLC results.
Typical recovery yield: approximately 60–80% of starting IgM content, depending on source material.
Express a recombinant IgM or IgG antibody from a DNA sequence before purification.
Validate antibody function before committing to full-scale purification.
Detect and remove residual Protein A from IgG affinity purification workflows.
Purified IgM antibodies serve as raw material for IgM-specific assay formats where early antibody response detection matters.
IgM typically appears before IgG during the immune response to infection, making IgM-specific ELISA and CLIA assays valuable for early-window diagnosis in TORCH panels, dengue serology, and viral hepatitis testing.
Purified IgM serves as a calibrator or reference standard for assays quantifying total serum IgM, used in immunodeficiency workups and monitoring of IgM-related conditions.
IgM's pentameric structure gives it high avidity and efficient complement fixation, properties exploited directly in agglutination-based rapid tests and complement-fixation assay development.
Browse our full Products page for infectious disease antigens that pair with IgM-specific assay development, or contact us to discuss your IgM purification project.
Answers to the questions clients most often ask about IgM purification.
IgM purification is the process of isolating IgM-class immunoglobulins from a crude source — hybridoma culture supernatant, ascites fluid, or serum — to a high-purity, low-aggregate, ready-to-use reagent. It differs fundamentally from IgG purification because Protein A and Protein G, the affinity ligands that make single-step IgG purification fast and simple, do not reliably bind IgM: Protein A has weak or no affinity for most IgM subclasses, and Protein G does not bind IgM at all. IgM purification instead relies on IgM's distinctive physical properties — its very large size (a pentamer of roughly 970 kDa, compared to approximately 150 kDa for IgG) and its low solubility at reduced ionic strength — using methods such as Euglobulin precipitation, ion-exchange chromatography, size-exclusion chromatography, and mixed-mode thiophilic adsorption.
Protein A and Protein G bind primarily to the Fc region of IgG through interactions specific to the IgG heavy-chain constant domains, a binding geometry that most IgM subclasses do not present. As a result, a standard Protein A affinity column — the default purification method for IgG — will pass most IgM straight through unbound, or bind it only weakly and with poor recovery. This is the central reason IgM purification requires a dedicated workflow rather than a simple swap of resin on an existing IgG purification process.
Sekbio's standard IgM purification workflow begins with Euglobulin cold precipitation, which exploits IgM's characteristic low solubility at reduced ionic strength and near-0°C temperature to selectively precipitate the IgM-rich euglobulin fraction away from albumin and most IgG. The redissolved precipitate then undergoes ion-exchange chromatography polishing, followed by size-exclusion chromatography (SEC) to resolve monomeric pentameric IgM from high-molecular-weight aggregates and any residual low-molecular-weight contaminants, given IgM's roughly 970 kDa native size.
Sekbio's IgM purification workflow targets purity greater than 90% by SDS-PAGE and SEC-HPLC, with post-purification aggregate content below 10% — a tighter aggregate specification than typical IgG purification, reflecting IgM's inherent tendency to self-associate at high concentration. Typical recovery yield ranges from approximately 60–80% of starting IgM content, depending on source material (hybridoma supernatant, ascites, or serum) and starting IgM concentration.
Sekbio purifies IgM from hybridoma cell culture supernatant, ascites fluid, and whole serum or plasma. Hybridoma supernatant is preferred for monoclonal IgM antibody production due to lower background contaminant load; ascites and serum sources require additional polishing steps to remove the higher albumin and IgG background typical of these matrices. Processing scale ranges from milligram R&D quantities to multi-gram OEM batches.
Purified IgM antibodies are used as capture or detection reagents in IgM-specific serology assays that detect the early antibody response to infection — since IgM typically appears before IgG during acute infection — including TORCH panel components, dengue and other arboviral IgM ELISAs, hepatitis IgM assays, and other acute-phase infectious disease serology formats. Purified IgM is also used as a calibrator or reference standard for total IgM quantification assays and in complement-fixation and agglutination assay development, where IgM's pentameric structure gives it high avidity.
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