{"product_id":"214-2099-g50-round-bottom-screw-cap-tube","title":"15–21 mL Test Tubes, Screw Caps, PS, Green — 214-2099-G50 | 1000\/Bag | Caplugs® Evergreen","description":"\u003ch2\u003e21 mL Round-Bottom Screw-Cap Test Tubes — PS, Natural Tube \/ Green Cap, 16 × 150 mm (214-2099-G50)\u003c\/h2\u003e\n\u003cp\u003eThese 21 mL polystyrene round-bottom test tubes ship unassembled with green screw caps in a 1000\/Bag pack, sized at 16 × 150 mm for large-volume sample storage, reagent preparation, and extended mixing workflows. Supplied non-sterile, they are the largest round-bottom tube in the Caplugs® Evergreen catalog, offering maximum working volume at the 15–21 mL scale. The green screw cap provides a re-sealable, leak-resistant closure and serves as an instant rack-level color identifier — a convention widely associated with lithium heparin plasma in clinical color-coding systems.\u003c\/p\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\u003ctable\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eSpecification\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003ePart Number (MPN)\u003c\/td\u003e\n\u003ctd\u003e214-2099-G50\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCapacity\u003c\/td\u003e\n\u003ctd\u003e21 mL\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDimensions\u003c\/td\u003e\n\u003ctd\u003e16 × 150 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eGeometry\u003c\/td\u003e\n\u003ctd\u003eRound Bottom\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMaterial\u003c\/td\u003e\n\u003ctd\u003ePolystyrene (PS)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTube Color\u003c\/td\u003e\n\u003ctd\u003eNatural (clear)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCap Style\u003c\/td\u003e\n\u003ctd\u003eScrew Cap\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCap Color\u003c\/td\u003e\n\u003ctd\u003eGreen\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAssembly\u003c\/td\u003e\n\u003ctd\u003eUnassembled (tubes and caps packed separately)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSterility\u003c\/td\u003e\n\u003ctd\u003eNon-Sterile\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePack Size\u003c\/td\u003e\n\u003ctd\u003e1000\/Bag\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBPA \/ Phthalate \/ Latex\u003c\/td\u003e\n\u003ctd\u003eBPA-Free, Phthalate-Free, Latex-Free\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCountry of Origin\u003c\/td\u003e\n\u003ctd\u003eUSA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch2\u003eApplications\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eSample storage at refrigerator (4 °C) or freezer (−20 °C) conditions, with the green cap providing immediate visual cohort identification at rack level\u003c\/li\u003e\n\u003cli\u003eSpecimen transport in tube carriers or secondary containment — the screw cap delivers a leak-resistant closure without additional film or parafilm\u003c\/li\u003e\n\u003cli\u003eReflex and add-on testing: re-cap and refrigerate after an initial run without transferring to a secondary aliquot tube\u003c\/li\u003e\n\u003cli\u003eBulk reagent and calibrator preparation, with the 21 mL volume accommodating multi-day storage between uses\u003c\/li\u003e\n\u003cli\u003eWater bath incubation up to 60 °C in standard 16 mm tube racks\u003c\/li\u003e\n\u003cli\u003eManual inversion mixing protocols — the longest tube in the Caplugs® Evergreen round-bottom family maximizes headspace for thorough mixing\u003c\/li\u003e\n\u003cli\u003eCentrifugation in clinical centrifuges fitted with 16 mm rotor positions\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eChemical Resistance\u003c\/h2\u003e\n\u003ctable\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eReagent \/ Condition\u003c\/th\u003e\n\u003cth\u003eCompatibility\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eAqueous buffers and saline\u003c\/td\u003e\n\u003ctd\u003eExcellent\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDilute acids and bases (routine chemistry pH range)\u003c\/td\u003e\n\u003ctd\u003eGood\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWater bath incubation ≤ 60 °C\u003c\/td\u003e\n\u003ctd\u003eCompatible\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEthanol \u0026gt; 70% \/ isopropanol\u003c\/td\u003e\n\u003ctd\u003eNot recommended\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAcetone \/ chlorinated solvents\u003c\/td\u003e\n\u003ctd\u003eNot recommended\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAromatic solvents (toluene, xylene)\u003c\/td\u003e\n\u003ctd\u003eNot recommended\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAutoclaving\u003c\/td\u003e\n\u003ctd\u003eNot compatible — PS is not autoclavable\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch2\u003eQuality \u0026amp; Procurement\u003c\/h2\u003e\n\u003cp\u003eMade in USA, these Caplugs® Evergreen tubes are manufactured from FDA-compliant, BPA-free, phthalate-free, latex-free polystyrene under ISO 9001 quality management controls. The natural (clear) tube wall provides sufficient optical clarity for visual inspection and direct spectrophotometric reading of aqueous samples. The unassembled pack format — tubes and caps supplied separately — lets staff apply caps at the point of sealing, reducing open-tube exposure time in high-throughput workflows. LabSupplies.com is an authorized dealer and ships from USA inventory, typically same business day for stocking items; tiered pricing is available for institutional, hospital, and grant-funded laboratories ordering ten or more bags.\u003c\/p\u003e\n\n\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003eAre these tubes and caps supplied already assembled?\u003c\/strong\u003e\u003cbr\u003eNo — the 1000\/Bag pack ships unassembled, with tubes and green screw caps packed separately. This lets laboratory staff cap each tube at the point of use, minimizing open-tube exposure during high-throughput processing.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eCan these tubes be autoclaved or used with organic solvents?\u003c\/strong\u003e\u003cbr\u003ePolystyrene is not autoclavable and is not resistant to alcohols above 70%, acetone, chlorinated solvents, or aromatic solvents. These tubes are intended for aqueous reagents, biological samples, and dilute acid\/base applications in the routine chemistry pH range.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhy is the cap green, and does it match clinical color-coding conventions?\u003c\/strong\u003e\u003cbr\u003eGreen is widely associated with lithium heparin plasma tubes in phlebotomy color-coding systems. Choosing green-capped storage tubes for the corresponding sample class allows staff to identify the analyte category at a glance across an entire rack without reading individual labels.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eIs a tubes-only option available if we already have caps on hand?\u003c\/strong\u003e\u003cbr\u003eYes — the Caplugs® Evergreen catalog includes a 21 mL round-bottom tube without a cap (part number 214-2097-010, 1000\/Bag). Additional screw-cap color options for the same 21 mL tube format include blue, orange, lavender, red, and yellow variants within the 214-2099 series.\u003c\/p\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e{\"@context\":\"https:\/\/schema.org\/\",\"@type\":\"Product\",\"name\":\"21 mL Round-Bottom Screw-Cap Test Tubes, PS, Natural Tube \/ Green Cap, 16 × 150 mm — 1000\/Bag Unassembled\",\"sku\":\"2142099G50E1\",\"mpn\":\"214-2099-G50\",\"brand\":{\"@type\":\"Brand\",\"name\":\"Caplugs® Evergreen\"},\"material\":\"Polystyrene (PS)\",\"color\":\"Green Cap \/ Natural Tube\",\"offers\":{\"@type\":\"Offer\",\"priceCurrency\":\"USD\",\"price\":\"264.50\",\"availability\":\"https:\/\/schema.org\/InStock\"}}\u003c\/script\u003e\n\u003cscript type=\"application\/ld+json\"\u003e{\"@context\":\"https:\/\/schema.org\/\",\"@type\":\"FAQPage\",\"mainEntity\":[{\"@type\":\"Question\",\"name\":\"Are these tubes and caps supplied already assembled?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"No — the 1000\/Bag pack ships unassembled, with tubes and green screw caps packed separately. This lets laboratory staff cap each tube at the point of use, minimizing open-tube exposure during high-throughput processing.\"}},{\"@type\":\"Question\",\"name\":\"Can these tubes be autoclaved or used with organic solvents?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Polystyrene is not autoclavable and is not resistant to alcohols above 70%, acetone, chlorinated solvents, or aromatic solvents. These tubes are intended for aqueous reagents, biological samples, and dilute acid\/base applications in the routine chemistry pH range.\"}},{\"@type\":\"Question\",\"name\":\"Why is the cap green, and does it match clinical color-coding conventions?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Green is widely associated with lithium heparin plasma tubes in phlebotomy color-coding systems. 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