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PROKEEP - Low Protein Binding Tube

Manufactured by Watson's proprietary precision tooling and materials.

A high quality tube with superior low protein binding properties.

What are PROKEEP Low Protein Binding Tubes ?

PROKEEP is designed for protein or peptide analysis (SDS-PAGE, HPLC, MS). It mitigates the risk of sample loss and improves the signals obtained.

Our uniquely blended plastic material avoid problems from elution.

PROKEEP tubes have reduced protein binding (low protein and peptide binding) as a result of our unique blend of materials used in the manufacturing and our high precision finish tooling without surface treatment.

Flat gate type


Note the flat bottom on our PROKEEP. The bottom material is as thin as the side walls. This eliminates the distorting lens effect and enhances the visual recognition of the sediment

Hyper Micro Tube


Contamination prevention

Our secure locking mechanism prevents contamination when opening and closing.

New Designed Hinge

Our newly designed hinge and top easy closure and gentle on the fingers

Easy to Open

Flat Top with a writable surface. The brim is made from thinner plastic to reduce the thumb pressure required when opening.


Super Clear polypropylene with clear graduation marks molded into the tube.

Writable Space

Writable marking space provided opposite the graduation marks.

Cat. No. Item Unit Case
PK-15C-500 PROKEEP low protein binding tube 1.5 mL bulk pack 500 tubes / bag 20 bags
PK-20C-500 PROKEEP low protein binding tube 2.0 mL bulk pack 500 tubes / bag 20 bags

Made from virgin polypropylene (autoclavable)
Centrifuge force:
PK-15C-500 / 20,000 x G (water 1.0 mL, 15 minutes)
PK-20C-500 / 7,000 x G (water 1.5 mL, 15 minutes)


PROKEEP's Low Protein binding performance

Protein and peptide loss when using plastic containers is caused by 2 factors.
(1) Solution residue that has not been collected by pipetting and centrifuge operation.
(2) Protein and peptide bonded to the containers
Many conventional container manufacturers have focused their development on either one of the above, but at Watson we have successfully addressed both factors.
Watson's PROKEEP containers are incomparable at in terms of achieving a low residue signal. PROKEEP's residue Signal is approximately 1 / 20 mill, which is 1 / 850 residue amount of other company's hydrophilic products in factor (1). No occurrence of peptide signal loss during 2 weeks-storage in factor (2).

(1) Residue Amount: Drawing 1
Test Method:

FITC-BSA solution (1 μg / mL) was put in a microtube and left for 1 hour at room temperature. The fluorescence of the surface of the tube was measured and digitized after removal of the solution, and then the residual protein mass was analyzed. This method evaluates the residual amount on the surface of the tube.


The residue amount on PROKEEP low protein binding tube is extremely small, which is 1 / 20 mill of the protein added. Tubes with hydrophilic surface treatment exhibited higher residue amount due to characteristic of the treatment.

(2) Binding of Protein and peptide to the tube: Drawing 2
Test Method:

A solution(0.1%TFA, 10 μL) equivalent to 500 fmol / μL peptide mix contained in Bruker Daltonics's Peptide calibration standard(#206195) was put in a tube and kept at 4℃ for 2 weeks. Then, the peptide in the tube was collected and analized by mass spectrometer(Bruker Daltonics's Ultraflex tof/ tof).


In the case of PROKEEPs low protein binding tube, all the peaks were detected after the 2 weeks. Our competitor's low binding tubes showed a part of the peaks were undetectable and peptide loss by binding was observed (Drawing 2B).

(3) Crystallization on MALDI Target Plate
Test Method:

In the crystalyzation process on a target plate, which is the indispensable process of MALDI type mass spectrometer analysis, a sample collected from another company's hydrophilic treated tube exhibited a disturbance in crystalization and it was difficult to conduct an accurate measurement, and elution of resin content was suspected(Dwg. 3). PROKEEPs low protein binding tube showed equivalent performance to the tube recommended by Bruker Daltonics.

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Microfabrication of plastic