Human serum collected via SST tube with controlled clot time and immediate centrifugation. Anticoagulant-free matrix ideal for serology, antibody detection, and small-molecule biomarker discovery.
Serum is the liquid fraction that remains after whole blood is allowed to clot and the clot is removed by centrifugation. Unlike plasma, serum contains no fibrinogen, no anticoagulants, and no cells — the coagulation cascade has run to completion, consuming clotting factors and platelets in the process. What remains is a protein-rich, cell-free matrix reflecting the stable biochemical composition of the donor's circulation at the time of draw.
SST (serum separator tube) collection uses a silica clot activator and a polymer gel barrier that migrates during centrifugation to create a physical seal between the clot and the serum supernatant. This prevents re-mixing and yields a clean serum fraction suitable for most immunoassay platforms. Standard clot time is 30–60 minutes at room temperature, per CLSI H18 guidelines.
When you buy serum specimens for research, it's the preferred matrix for serology, many clinical chemistry analytes, and assays where anticoagulant interference is a documented concern. It is not appropriate for coagulation assays (use citrate plasma) or applications requiring intact cellular material.
| Parameter | Detail |
|---|---|
| Typical Volume | 1.5–4 mL per specimen (approximately 50–55% yield from whole blood volume) |
| Collection Tube | SST (serum separator tube) with silica clot activator and polymer gel barrier |
| Processing | 30–60 min room-temperature clot time; centrifuge at 1,200–1,500 × g for 10 min |
| Storage | -80°C for long-term; stable at -20°C for 6–12 months for most protein analytes |
| Turnaround | 2–5 business days from order confirmation; same-day processing before shipment |
| Documentation | Clot time, centrifugation parameters, collection date/time, donor demographics, IRB consent |
Provide aliquot volume per specimen, quantity, fasting requirements (if any), and donor inclusion/exclusion criteria including disease state, medication use, and demographics.
Donors are matched to your protocol criteria. Fasting donors are scheduled for morning draws. All collection follows standardized pre-analytical SOPs.
Serum is aliquoted after centrifugation, placed on dry ice, and shipped with full collection metadata and chain-of-custody documentation.
Serum is free of anticoagulants that can interfere with complement activity and certain immunoglobulin binding assays. Many reference serology platforms (ELISA, chemiluminescent immunoassay) are validated on serum, not plasma. The absence of fibrinogen also reduces background in some bead-based multiplex formats.
SST tubes with clot activator require 30 minutes at room temperature. Tubes without activator require 30–60 minutes. We follow CLSI H18 guidelines — centrifugation begins immediately after confirmed clot formation to minimize pre-analytical variability and analyte degradation from prolonged cell contact.
Yes — serum is widely used for metabolomics. The absence of EDTA or heparin eliminates anticoagulant-related ion suppression in mass spectrometry. Note that platelet activation during clotting releases lipid mediators (thromboxane, serotonin) into serum. If these are analytes of interest, EDTA plasma may better reflect in vivo levels.
Submit your protocol requirements and receive a quote within 24 hours.
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