21 mL Round-Bottom Test Tubes with Orange Screw Caps — PS, 16 × 150 mm, 1000/Bag (214-2099-E50)
These 21 mL polystyrene round-bottom test tubes ship with matching orange screw caps in an unassembled 1000/Bag pack, allowing lab staff to apply caps at the point of sealing and minimize open-tube exposure in high-throughput workflows. At 16 × 150 mm, they represent the largest round-bottom tube in the Caplugs® Evergreen catalog and are suited to bulk reagent preparation, extended inversion mixing, large-volume culture, and multi-day sample storage. The orange screw cap delivers a leak-resistant re-close for transport and reflex testing, and its vivid color provides immediate rack-level identification for STAT lanes, immunoassay panels, or designated patient cohorts.
Technical Specifications
| Specification | Value |
|---|---|
| Part Number (MPN) | 214-2099-E50 |
| Capacity | 21 mL |
| Dimensions | 16 × 150 mm |
| Geometry | Round Bottom |
| Material | Polystyrene (PS) |
| Tube Color | Natural (clear) |
| Cap Style | Screw Cap |
| Cap Color | Orange |
| Assembly | Unassembled (tubes and caps supplied separately) |
| Sterility | Non-Sterile |
| Pack Size | 1000/Bag |
| BPA / Phthalate / Latex | BPA-Free, Phthalate-Free, Latex-Free |
| Country of Origin | USA |
Applications
- Sample storage at refrigerated (4 °C) or frozen (−20 °C) conditions with secure screw-cap re-closure
- Sample transport in tube carriers or secondary containment, with the screw cap providing a leak-resistant seal
- Reflex and add-on testing — re-cap and refrigerate after the initial analytical run without aliquot transfer
- Bulk reagent, calibrator, and control preparation where the full 21 mL working volume is needed
- Water bath incubation at 37 °C in standard 16 × 150 mm tube racks
- Manual inversion mixing protocols that benefit from the maximum headspace of the longest tube in this product family
- Centrifugation in clinical centrifuges equipped with a 16 mm rotor adapter
- Color-coded cohort or analyte-class identification — orange caps are commonly assigned to STAT/priority lanes or specific immunoassay panels
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% / isopropanol | Not recommended |
| Acetone | Not recommended |
| Aromatic or chlorinated solvents | Not recommended |
| Autoclave sterilization | Not compatible — PS is not autoclavable |
Quality & Procurement
Made in USA, these tubes are produced by Caplugs® Evergreen under ISO 9001 quality management from FDA-compliant, BPA-free, phthalate-free, and latex-free polystyrene resin. The natural PS wall offers optical clarity suitable for direct visual inspection and spectrophotometric reading without tube-to-tube transfer. LabSupplies.com is an authorized dealer carrying USA inventory and ships stocking items typically the same business day; volume pricing is available for institutional, clinical, and grant-funded laboratories placing multi-bag orders.
Frequently Asked Questions
Are the tubes and caps packaged already assembled?
No — part number 214-2099-E50 is supplied unassembled, with tubes and orange screw caps packed separately in the same bag. This lets lab staff cap each tube at the moment of sealing, reducing open-tube exposure time in busy workflows.
Can these tubes be used with organic solvents or autoclaved?
Polystyrene is not recommended for use with acetone, alcohols above 70%, or aromatic and chlorinated solvents, and it cannot be autoclaved. For solvent-heavy or autoclave-required applications, a polypropylene tube is a better choice.
Why is the cap orange, and does the color carry any standard meaning?
Orange is the cap color assigned to this SKU within the Caplugs® Evergreen 21 mL screw-cap series. In many clinical and research labs, orange is conventionally reserved for STAT or priority sample lanes and specific immunoassay or analyte-class panels, making it easy to identify the correct tubes at a glance across a fully loaded rack.
Is a tubes-only (no cap) option or other cap colors available for the same 21 mL format?
Yes. The same 16 × 150 mm PS round-bottom tube without a cap is available as a separate SKU, and the 21 mL screw-cap family is offered in blue, green, lavender, red, and yellow cap colors in addition to this orange version — allowing labs to standardize on one tube size while color-coding multiple sample classes or study cohorts.