Heathrow Scientific Black Microcentrifuge Tubes - HS4323K | Light-Sensitive, 18,000 × g

A clear tube is a liability when your sample contains fluorescent dyes, luciferase substrates, photolabile crosslinkers, or any compound that degrades under ambient lab lighting. Heathrow Scientific 1.5 mL Black Microcentrifuge Tubes (HS4323K) are injection-molded from opaque black polypropylene to block visible light at the tube wall — at every step, from the bench incubation through centrifugation to short-term storage. Foil-wrapping clear tubes is an unreliable workaround that introduces handling steps and fails the moment the wrap is disturbed. These tubes solve the problem at the material level. Certified DNase-free, RNase-free, and pyrogen-free with a maximum RCF of 18,000 × g — the highest rating in the Heathrow Scientific microtube line.

Features and Benefits

• Opaque black polypropylene blocks visible light across 380–700 nm — eliminates photobleaching of FITC, Cy3, Cy5, PE, APC, and Alexa Fluor conjugates; protects photodegradable substrates (luciferase, psoralen, diazirine-based crosslinkers) during bench incubations, centrifuge runs, and storage

• Highest RCF in the Heathrow Scientific microtube line — 18,000 × g — the thicker-wall black PP formulation adds structural margin; handles protein aggregate pelleting, silica bead collection, and high-speed clarification steps that push the speed limits of standard benchtop microcentrifuges

• DNase-free, RNase-free, and pyrogen-free certified — light-sensitivity does not compromise molecular contamination standards; light-sensitive work often overlaps with nuclease-sensitive RNA or protein assays that require the same clean-tube guarantee

• Contrasting-color graduation marks at 0.1, 0.5, 1.0, and 1.5 mL — printed in contrasting color for legibility against the opaque black wall under standard overhead lab lighting without a backlight; full scale to 1.5 mL for complete volume reference

• Attached flat cap, syringe-pierceable for closed-system aliquotting — closed-system access prevents light entry during repeat sampling; flat cap profile is compatible with most tube label printers and barcode labeling systems used in biobank and sample tracking workflows

• Autoclavable for combined sterility and light-protection requirements — lentiviral vector production, fluorescent protein expression assays, and bioluminescent construct work may require both sterility and light protection simultaneously; these tubes satisfy both

Specifications

Laboratory Applications

• Immunofluorescence & Flow Cytometry Sample Prep — antibody-dye conjugates (PE, APC, FITC, Alexa Fluor series) photobleach during 30–60 minute room-temperature or 4°C incubation steps; black tubes preserve signal intensity from staining through acquisition, directly protecting assay sensitivity and MFI accuracy

• Bioluminescence Assays — Luciferase & NanoLuc — luciferase substrate solutions begin degrading within minutes of light exposure; black tubes preserve substrate activity from preparation through the measurement window, protecting the signal dynamic range needed for accurate reporter gene quantification

• Photolabile Crosslinker & Chemical Biology Workflows — diazirine, benzophenone, and aryl azide crosslinkers must be shielded from all light sources until deliberate UV activation; black tubes protect reagent integrity during conjugation reactions, incubation steps, and pre-activation handling at the bench

• Environmental & Analytical Chemistry with Photodegradable Analytes — certain pesticide residues, pharmaceutical compounds, and environmental contaminants photodegrade on timescales that compromise clear-tube handling; black tubes maintain sample integrity from collection to instrument injection in LC-MS and GC-MS analytical workflows

• Fluorescent Protein Expression & Purification (GFP, mCherry, tdTomato) — bacterial and mammalian lysates containing fluorescent fusion proteins are processed in black tubes to minimize background from photobleached fragments that confound downstream spectrofluorometry or imaging quantification

Frequently Asked Questions

How much light do these tubes actually block — do I still need to work in a dark room?
The opaque black polypropylene blocks essentially all visible light transmission (380–700 nm) through the tube wall under standard overhead fluorescent and LED lab lighting. For extremely photolabile compounds with very short photodegradation half-lives (certain psoralen derivatives, some photocleavable protecting groups), working under dim or red safelight during open-tube transfer steps adds an additional margin. Once capped, these tubes provide effective protection for the great majority of light-sensitive lab applications without additional precautions.

How do I read the graduation marks on a black tube?
The graduation marks are printed in a contrasting color visible against the black polypropylene under standard overhead lab lighting. Hold the tube at eye level against a nearby light source for the most accurate reading. The full 0.1, 0.5, 1.0, and 1.5 mL scale is visible without a backlight or UV transilluminator.

Why is the max RCF higher on the black tube (18,000 × g) than the natural 1.5 mL tube (16,400 × g)?
The HS4323K is manufactured in Taiwan to a slightly different wall thickness specification than the China-manufactured natural 1.5 mL tubes. The additional wall thickness in the black formulation provides the higher RCF margin. In practice, most benchtop microcentrifuges top out at 14,000–16,000 × g, so both tubes operate well within their rated limits at maximum machine speed. The higher RCF rating provides additional safety margin for high-speed rotors.

Can I use these for long-term storage at −80°C?
Yes. Polypropylene is rated for −80°C storage and standard ultra-low temperature freezer conditions. The attached flat cap prevents the cap-loss failure mode during repeated freeze-thaw cycles. The opaque black wall continues to protect light-sensitive samples during brief light exposure at the freezer door. Label the cap and tube body with a cryogenic-rated marker or cryo-label for identification in −80°C storage.

Quality Assurance

Heathrow Scientific HS4323K Black Microcentrifuge Tubes are manufactured in Taiwan under ISO-certified production controls. Each lot is certified DNase-free, RNase-free, and pyrogen-free with documentation available for quality system and regulatory submissions. The opaque black polypropylene formulation is tested for light-blocking performance across the visible spectrum. The 18,000 × g RCF rating reflects structural testing of cap seal integrity and tube wall performance at maximum centrifugal force. Tubes ship in sealed bulk packs of 500 to maintain certification status.

Academic and Institutional Pricing

LabSupplies.com offers tiered quantity pricing for academic and research institutions. As an authorized dealer, we ship directly from USA inventory.