5.0 mL Round-Bottom PS Sterile Test Tubes with Two-Position Snap Cap, 12 × 75 mm — Flow Cytometry & Serology (222-2036-050)
These 5.0 mL polystyrene round-bottom test tubes ship sterile in 25/Bag (unassembled) and are the industry-standard vessel for flow cytometry, FACS-based immunophenotyping, and manual tube serology. The 12 × 75 mm format fits every major flow cytometer tube holder, while the two-position snap cap clicks between a vented position — allowing gas exchange during incubation or centrifugation — and a fully closed position for sealed storage and aerosol containment.
Technical Specifications
| Specification | Value |
|---|---|
| Part Number (MPN) | 222-2036-050 |
| Capacity | 5.0 mL |
| Dimensions | 12 × 75 mm |
| Geometry | Round Bottom |
| Material | Polystyrene (PS) |
| Color | Natural (clear) |
| Cap / Closure | Two-position snap cap — vented and fully closed positions |
| Assembly State | Unassembled (tube and caps packed together; lab-assembled before use) |
| Sterility | Sterile |
| Pack Size | 25/Bag |
| BPA / Phthalates / Latex | BPA-Free, Phthalate-Free, Latex-Free |
| Country of Origin | USA |
Applications
- Flow cytometry (FACS) & cell sorting: The 12 × 75 mm format seats directly in BD FACSCanto™, LSRFortessa™, Attune™, CytoFLEX™, and virtually all other major flow cytometer tube holders; the cap is removed at the instrument nozzle for cell sorters.
- Immunophenotyping: The 5.0 mL capacity accommodates standard surface marker staining protocols — typically 50–100 µL sample plus antibody cocktail — with room for lyse/wash steps.
- Intracellular staining: Polystyrene is compatible with methanol-based and saponin-based fixation/permeabilization protocols used in cytokine and transcription factor panels.
- Tube serology & blood bank testing: Optical clarity enables direct visual reading of agglutination reactions — button, partial agglutinate, and dispersed cell patterns are all easily distinguished through the clear PS wall.
- Centrifugation wash steps: The round-bottom geometry forms a tight, uniform cell pellet at up to 600 × g, reducing cell loss during wash cycles.
- Short-term cell culture & stimulation: The vented snap-cap position supports CO₂ exchange in a humidified incubator, while the closed position seals the tube for transport between the incubator and the flow cytometer.
Compatibility
The 12 × 75 mm round-bottom format is the universal standard tube geometry for flow cytometry and represents a direct drop-in replacement for BD® 12 × 75 mm test tubes used in those workflows. These tubes seat correctly in the standard 12 × 75 mm tube holders found on BD FACSCanto™, BD LSR™, BD Attune™, Beckman Coulter CytoFLEX™, and comparable instruments. For blood bank and clinical serology workflows, the round-bottom geometry and PS clarity match the standard manual agglutination tube used in tube-method crossmatch and antibody identification panels. Always confirm inner-diameter tolerances against your specific instrument holder specification when transitioning from an OEM supply.
Chemical Resistance
| Reagent / Condition | Compatibility |
|---|---|
| Aqueous buffers (PBS, HBSS, saline) | Excellent |
| Dilute acids and bases | Good |
| Methanol (fixation protocols) | Compatible — short-term contact |
| Saponin-based permeabilization reagents | Compatible |
| Ethanol >70% | Not recommended — causes crazing/cracking |
| Acetone / chloroform / aromatic solvents | Not recommended — dissolves PS |
| Autoclaving | Not suitable — PS is not autoclavable |
Quality & Procurement
Made in USA, these Caplugs® Evergreen tubes are molded from BPA-free, phthalate-free, latex-free polystyrene resin under ISO 9001 quality management and supplied sterile — ready for regulated clinical and research workflows without additional decontamination steps. The unassembled 25/Bag format is the preferred procurement configuration for high-volume flow cytometry and blood bank labs where assembly is performed at the bench just prior to use. LabSupplies.com is an authorized Caplugs® Evergreen dealer and ships from USA inventory, typically the same business day for stocking items, with volume and institutional pricing available for labs with recurring demand.
Frequently Asked Questions
Are these tubes sterile as shipped?
Yes — the tubes and snap caps arrive sterile-packed in each bag. Because the tubes ship unassembled (caps loose in the same bag), users should assemble each tube using aseptic technique immediately before use to maintain sterility of the interior.
What does "unassembled" mean, and does it affect workflow?
Unassembled means the two-position snap cap is not pre-mated to the tube at the factory; the tube body and caps are packed together in the same bag. Lab staff click the cap onto each tube before use. This configuration is standard in bulk clinical and research purchasing because it reduces per-unit cost and allows users to load caps in the orientation needed for their protocol from the outset.
How does the two-position snap cap work?
The cap clicks to two distinct positions: Position 1 is a vented/partially open state that allows gas exchange — useful during centrifugation, CO₂ incubation, or cell stimulation. Position 2 is a fully closed, sealed state for sample storage, transport, and aerosol containment at the flow cytometer or after fixation.
Will these tubes fit my flow cytometer's sample injection port?
The 12 × 75 mm round-bottom format is the industry-standard tube dimension for flow cytometry and fits the tube holders and sample injection systems on BD FACSCanto™, BD LSR™, Beckman Coulter CytoFLEX™, Thermo Fisher Attune™, and most other major platforms. If you are using an automated high-throughput loader or a non-standard tube rack, verify the inner-diameter specification of the holder against the 12 mm outer diameter of these tubes before placing a bulk order.