Frequently Asked Questions

HAEM-LOKᵀᴹ  Collection Tube for Cell-Free DNA

What size needle is recommended for venous blood collection of the HAEM-Lok™ Tube?

A 21G or larger diameter needle is recommended to minimize hemolysis. Either a BD “butterfly needle” (BD Cat. No. 367281 Blood Collection Set with Tubing) or standard safety tube holder may be used.

If several types of blood samples are to be taken, what is the order of blood draw for the HAEM-Lok™ Tube?

It is recommended that the HAEM-Lok™ Tube be drawn after an EDTA tube.

What is the total capacity of the HAEM-Lok™ Tube?

The total fill volume is approximately 9.0 mL.

How soon after blood collection in a HAEM-Lok™ Tube should the tube contents be mixed?

As soon as possible, preferably within 2 min. Invert gently after collection to mix the additive with the blood. Please refer to the Instructional Video.

Should the gel matrix still be at the bottom of the tube after mixing?

Yes. The matrix is not soluble. It will remain at the bottom of the tube until after centrifugation.

How long and at what temperature should a filled HAEM-Lok™ Tube be held before centrifugation?

The HAEM-Lok™ Tube should be held at room temperature for no longer than 2 hr after blood collection and prior to centrifugation. Alternatively, the filled Tube may be held at 4C for up to 3 days after blood collection and prior to centrifugation.

Why is there a mixing step just prior to centrifugation?  

A variable degree of cell settling occurs prior to centrifugation. Mixing redistributes the cells back to the optimal configuration to remove them during the centrifugation step.

The protocol indicates that optimal conditions for centrifugation are 1800g, 10 min at 22C in a swinging bucket rotor. Can other speeds or rotors be used? 

The HAEM-Lok™ Tube can be centrifuged in a swinging-bucket rotor at 1600 – 3000g or in a fixed-angle rotor at 1100g with similar results.

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