21 mL Round-Bottom Test Tubes with Lavender Screw Caps, PS, 16 × 150 mm — 214-2099-L50 (1000/Bag, Unassembled)
These 21 mL polystyrene round-bottom test tubes pair with lavender screw caps for leak-resistant closure in sample storage, transport, and reflex testing workflows. Measuring 16 × 150 mm, they represent the largest round-bottom tube in the Caplugs® Evergreen catalog, providing maximum working volume and headspace for inversion mixing, bulk reagent preparation, and large-volume culture or reaction protocols. Supplied non-sterile and unassembled in 1000/Bag packaging, tubes and caps arrive separately so lab staff can apply closures at the precise moment of sealing.
Technical Specifications
| Specification | Value |
|---|---|
| Part Number (MPN) | 214-2099-L50 |
| Capacity | 21 mL |
| Dimensions | 16 × 150 mm |
| Geometry | Round bottom |
| Closure Type | Screw cap |
| Material | Polystyrene (PS) |
| Tube Color | Natural (clear) |
| Cap Color | Lavender |
| Sterility | Non-Sterile |
| Pack Size | 1000/Bag, Unassembled |
| BPA / Phthalate / Latex | BPA-Free, Phthalate-Free, Latex-Free |
| Country of Origin | USA |
Applications
- Refrigerated (4 °C) or frozen (−20 °C) sample storage with rack-level lavender cap identification for EDTA-anticoagulated specimens and plasma aliquots
- Sample transport in tube carriers or secondary containment — the screw cap provides a leak-resistant closure for inter-department or off-site shipment
- Reflex and add-on testing: re-cap and refrigerate after the initial analytical run without performing an aliquot transfer
- Bulk reagent, calibrator, and working-solution preparation requiring a large working volume and secure multi-day storage
- Water bath incubation at 37 °C using standard 16 × 150 mm tube racks
- Inversion-mixing protocols that benefit from maximum headspace at the 15–21 mL scale
Chemical Resistance
| Reagent / Condition | Compatibility |
|---|---|
| Aqueous buffers and saline | Excellent |
| Dilute acids and bases (routine chemistry pH range) | Good |
| Water bath incubation up to 60 °C | Compatible |
| Ethanol > 70% / alcohols | Not recommended |
| Acetone / aromatic solvents | Not recommended |
| Chlorinated solvents | Not recommended |
| Autoclave sterilization | Not compatible |
Quality & Procurement
Made in USA, these Caplugs® Evergreen test tubes are manufactured under ISO 9001 quality management from FDA-compliant, BPA-free, phthalate-free, latex-free polystyrene resin. The natural-clarity PS wall enables direct visual inspection of contents and is suitable for spectrophotometric reading without tube transfer. LabSupplies.com is an authorized dealer of Caplugs® Evergreen consumables and ships from USA inventory, typically same business day for stocking items. Volume pricing is available for institutional, clinical, and grant-funded laboratories purchasing ten or more bags.
Frequently Asked Questions
Why is the cap lavender rather than another color?
Lavender corresponds to the K2/K3-EDTA tube color convention widely used in phlebotomy and clinical laboratory practice. Carrying that convention through to downstream storage vessels gives hematology, EDTA plasma, and molecular biology workflows an immediate, rack-level visual identifier without additional labeling.
What does "unassembled" mean for this pack?
Tubes and lavender screw caps are packaged separately within the same 1000/Bag unit. Lab staff apply caps at the point of sealing, which minimizes open-tube exposure time during high-throughput accessioning and processing workflows.
Are these tubes compatible with organic solvents or autoclaving?
No — polystyrene is not resistant to acetone, alcohols above 70%, aromatic solvents, or chlorinated solvents, and it is not autoclavable. These tubes are optimized for aqueous buffers, dilute reagents, and biological samples within the routine clinical chemistry pH range.
Is this tube available with other cap colors or without a cap?
Yes. The same 21 mL, 16 × 150 mm round-bottom tube is offered in a full screw-cap color set — including blue, orange, green, red, and yellow — and is also available as a tubes-only option (no cap) in a 1000/Bag format, enabling labs to standardize on a single tube geometry across multiple color-coded workflows.