productListingPage:CATEGORIES

productListingPage:NO_CATEGORIES_FOUND

productListingPage:CATEGORIES

productListingPage:NO_CATEGORIES_FOUND

Globe Scientific Micro-Hematocrit Capillary Tubes — Plain, Heparinized, and Plastic

Globe Scientific micro-hematocrit capillary tubes are precision-dimensioned 75 mm tubes (I.D. 1.15 mm, fill volume ~75 µL) for packed cell volume determination, available in five SKUs: plain untreated glass (blue tip, 51602), sodium heparin glass (red tip, 51603), ammonium heparin glass (green tip, 51607), unbreakable polypropylene plastic (blue tip, 51620), and pre-calibrated borosilicate for blood gas analyzers (I.D. 0.55 mm, 51628). All formats fit standard hematocrit centrifuges rated to 14,500 RPM.

MBP stocks all Globe Scientific capillary tube SKUs with direct PO ordering for clinical and research labs across the USA, Canada, and worldwide. For further details, contact customerservice@mbpinc.net

Capillary Tubes

productListingPage:PER_PAGE:

productListingPage:SORT_BY:

No Products Found

Back to home

What are Micro-Hematocrit Capillary Tubes?

Micro-hematocrit capillary tubes are precision-dimensioned, single-use tubes used to determine packed cell volume (PCV/hematocrit) in whole blood specimens. Manufactured by Globe Scientific in soda lime glass and polypropylene plastic formats, they have an internal diameter of 1.15 mm ± 0.05 mm, an outer diameter of 1.5 mm ± 0.05 mm, a length of 75 mm ± 1 mm, and a fill volume of approximately 75 µL. Tubes fill rapidly by capillary action from a finger-stick puncture or from the meniscus of a blood collection tube; one end is sealed with sealing clay after filling, and the tube is centrifuged at 10,000–14,500 RPM for 5 minutes. The resulting packed red cell fraction is read against a hematocrit reader card. Globe Scientific offers three glass variants—plain (blue tip), ammonium heparin (green tip), and sodium heparin (red tip)—plus one unbreakable plastic format and a pre-calibrated borosilicate tube (I.D. 0.55 mm) for blood gas instrumentation.

What You Will Find

Available in high-durability plastic or traditional soda lime glass for secure blood cell volume testing.
Pre-calibrated, high-clarity tubes designed for superior thermal and chemical resistance.
Precision steel wires engineered for thorough sample homogenization in blood gas capillaries.
Essential support tools, including sealing wax and trays, to keep your micro-samples locked and stabilized.

How to Choose the Right Capillary Tube SKU

Plain (Untreated) — Blue Tip (Globe Scientific catalog 51602)
Use plain tubes when collecting blood from a pre-anticoagulated source: EDTA blood collection tubes, citrate tubes, or any specimen already containing an anticoagulant. Adding a heparinized tube to EDTA blood is unnecessary and may alter the hematocrit result due to dilution of the anticoagulant chemistry. Fill directly from the meniscus of the blood collection tube using capillary action.

Ammonium Heparinized — Green Tip (catalog 51607)
Use ammonium heparin tubes for direct finger-stick or heel-stick collection when the patient's blood has not been pre-anticoagulated. Ammonium heparin does not alter RBC morphology and is acceptable for most hematocrit determinations. Green tip is the most commonly stocked heparinized capillary tube format in clinical and point-of-care settings.

Sodium Heparinized — Red Tip (catalog 51603)
Sodium heparinized tubes are functionally equivalent to ammonium heparin tubes for hematocrit but are preferred in neonatal and pediatric heel-stick programs where some institutions specify sodium heparin per protocol. Confirm your institutional SOP anticoagulant specification before selecting between red and green tip formats.

Plastic (Unbreakable) — Blue Tip (catalog 51620)
Polypropylene capillary tubes have the same external dimensions as glass formats and fit standard hematocrit centrifuges. They eliminate glass shard hazards during filling, sealing, and post-centrifugation reading. Mandatory in many high-volume outpatient draw settings under occupational health and safety programs. Fill volume and hematocrit results are equivalent to glass when tubes meet dimensional specifications.

Pre-Calibrated Borosilicate Glass (catalog 51628)
I.D. 0.55 mm ± 0.03 mm — narrower than standard hematocrit tubes. Designed for blood gas analyzers and co-oximeters that require a specific microvolume fill tolerance. Do not use these for routine hematocrit centrifugation; the narrower bore and smaller volume are not compatible with hematocrit reader cards calibrated for 75 µL fill.

Specifications Context

All Globe Scientific 75 mm micro-hematocrit capillary tubes are manufactured under ISO 9001:2015 quality management. Glass tubes are soda lime glass except catalog 51628 (borosilicate). Standard centrifugation protocol: 10,000–14,500 RPM for 5 minutes; minimum required centrifuge radius for complete packing is 8 cm. Sealing clay (catalog 5162) is available separately. Post-centrifugation results are read on a hematocrit reader card calibrated for the 75 µL fill volume and 75 mm column length. Reference ranges: adult male 38–50% PCV; adult female 35–47% PCV; newborn 44–64% PCV. As of 2026, Globe Scientific capillary tubes are stocked by MBP and available for same-case reorder via PO.

Don't let your micro-samples vanish. Browse our capillary range and contact the MBP team for a quote today.

FAQ

Globe Scientific micro-hematocrit capillary tubes are 75 mm ± 1 mm in length, with an inner diameter of 1.15 mm ± 0.05 mm and an outer diameter of 1.5 mm ± 0.05 mm, giving a fill volume of approximately 75 µL. They are manufactured from soda lime glass (catalogs 51602, 51603, 51607) or polypropylene plastic (51620) and fit standard 75 mm hematocrit centrifuges rated to 14,500 RPM.

Use plain capillary tubes (blue tip, catalog 51602) when filling from an EDTA or citrate anticoagulated blood collection tube — the blood is already anticoagulated and no additional heparin is needed. Use heparinized tubes (green tip ammonium heparin 51607, or red tip sodium heparin 51603) only when collecting blood directly from a finger-stick or heel-stick puncture where the blood has had no prior anticoagulation.

Catalog 51628 is a pre-calibrated borosilicate glass capillary tube with an I.D. of 0.55 mm ± 0.03 mm—narrower than standard hematocrit tubes. It is designed for blood gas analyzers and co-oximetry instruments that require a precision-controlled microvolume fill. These tubes should not be used for routine hematocrit centrifugation; the bore and volume are not compatible with standard hematocrit reader cards.

Polypropylene capillary tubes (catalog 51620) eliminate the occupational sharps hazard from glass breakage during filling, sealing, and post-centrifugation handling. Many clinical safety programs require plastic capillary tubes in high-volume outpatient draw settings under OSHA Bloodborne Pathogens Standard (29 CFR 1910.1030) to reduce percutaneous injury risk. Hematocrit results are equivalent between glass and plastic when dimensional tolerances are met.

After filling the capillary tube to at least three-quarters of its 75 mm length by capillary action, one end is sealed by inserting it approximately 5 mm into sealing clay (Globe Scientific catalog 5162) and twisting gently to create a clay plug. Inspect the seal before centrifugation — an incomplete seal allows blood to eject into the centrifuge during spinning and produces an invalid result.

Micro-hematocrit capillary tubes require a dedicated hematocrit centrifuge with a head designed to hold 75 mm tubes horizontally or at a fixed angle, typically rated to 10,000–14,500 RPM. Standard bench-top centrifuges with swing-bucket or fixed-angle rotors for 15 mL and 50 mL tubes are NOT appropriate substitutes; only a head specifically designed for 1.5 mm O.D. capillary tubes achieves the centrifugal force and tube geometry required for complete cell packing.

Reference ranges for micro-hematocrit (packed cell volume): adult males 38–50%; adult females 35–47%; newborns 44–64% (first day of life). Values below the reference range indicate anemia; values above indicate polycythemia or dehydration. Hematocrit is interpreted alongside hemoglobin, red cell count, and red cell indices for complete anemia evaluation.

Yes. MBP stocks Globe Scientific micro-hematocrit capillary tubes in all four glass variants (catalogs 51602, 51603, 51607, 51628) and the plastic format (51620), with direct PO-based ordering and responsive human support for institutional accounts — available for labs across the USA, Canada, and worldwide.

We provide the highest quality of products and anytime customer service.