This is a superloop for applying large volumes of sample in an FPLC System using 50ml syringes.

Use

1. Fill one 50ml syringe with the sample (up to 60ml fit)
2. Place it in the superloop and rotate the syringe so that it is held in place by its lugs
3. Place the second empty (buffer) syringe in the loop and extend its plunger util it meets the plunger of the sample syringe.
4. Put on the Clamp and screw it into place with 4x M3 SHCS
5. Attach a capillary to the Luer Lock connector of the sample syringe and to the sample loop port on the FPLC system (the port going to the column) and make sure not to introduce air
6. Also attach a capillary to the empty syringe and the sample loop port of the FPLC (the port coming from the pump)
7. Run the pump until the pressure rises to the intended operating pressure (see note about volumes)

Preparation & Assembly

1. Print using material of choice but with thick walls (e.g. 1.8-2.4mm) and good infill (e.g. 20% gyroid) as described in the notes
2. Attach both halves of the superloop base via its dovetails connectors
3. Insert threaded inserts for M3 into the respective holes

Hardware needed

1. 4x M3 screws
2. 4x M3 threaded inserts
3. 2x 50ml Luer Lock syringes (see Note)
4. Capillaries (e.g. 1/16")
5. Luer-Lock to capillary adaptor (we used a Luer Lock to 10-32 UNF conical adaptor and 10-32 UNF 1/16" fingertight fittings)
6. Capillary adaptors to the FPLC system (we used 10-32 UNF conical fingertight fittings)

Notes

Printing

This assembly has to withstand the pressure of the FPLC system. Therefore it is advisable to print it for increases rigidity (i.e. thick walls and higher infill). We used normal PLA with 4 perimeters (2.4mm) walls and 20% gyroid infill and it holds well. We tested the device up to a pressure of 0.5MPa.

Syringes

This was designed to be used with Ecolab Ecoject 50ml Luer Lock syringes. It should be compatible with other 50ml syringes like BD Plastipak and B.Braun Omnifix. It is however not compatible with B.Brauin 50ml Perfursor syringes. I have attached the Fusion Model and a STEP file for anyone who wants to make changes and adapt it for other syringes should it not fit.

Sample volumes

Depending on how much air is in the empty (buffer) syringe the volume dispensed from the sample syringe is reduced by the volume of buffer needed to pressurise the empty (buffer) syringe. For this reason it is advisable to pre-fill the buffer syringe with liquid if less than the maximum sample volume is used. Still, air bubbles in the buffer syringe will take up some volume before sample is ejected from the sample syringe.

We program the correct sample volume that was loaded in the sample syringe in the FPLC run program and then at the beginning of the injection step hold the program so that the pump continues to pump liquid without counting the volume until the pressure rises to the operating pressure. Then we continue the program..

If more than 50-60ml of sample need to be applied we program the higher sample volume in the FPLC program and run the device until the empty sample syringe causes an overpressure error and pauses the device. We then swap syringes and continue.

This design is based on an idea by Hüseyin Besir: https://www.laborjournal.de/rubric/tricks/tricks/trick175.php

If you find this helpful, you can cite this mode als follows:

Pfisterer, M. (2024). FPLC Superloop using 50ml Syringes (Version 1.x). NIH 3D. https://doi.org/10.60705/3DPX/21635.1