Rapid filtration system - RFS-4

Applications :

• ENZYMOLOGY
• AUTOMATIC ENZYME ASSAYS
• RAPID KINETICS
• MEMBRANE BIOCHEMISTRY
• MEASUREMENTS OF IONIC FLUXES OF TRANSPORT
• MOLECULAR PHARMACOLOGY
• Etc.

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Filtration is a very inexpensive technique which, usually, requires nothing more than a filter set, a filter holder, a vacuum pump and a pipette. In many instances, however, this is not sufficient since even an extremely skilled person cannot perform a filtration experiment in less than a few seconds. This time is by far too long for initial rate measurements or for transient state studies.
With the Rapid-Filtration-System we open for the first time the possibility to perform filtration experiments in the millisecond range.
It is now possible to evaluate, down to a very short time scale, the time course of binding of an enzyme effector or the kinetics of transport of a metabolite without using irreversible inhibitors as in the quench-flow or inhibitor-stop techniques.

High reproducibility of the filtration experiments

The Rapid-Filtration-System consists of a fine mechanical design whose functions are microprocessor controlled. This enables the operator to perform highly reproducible filtration experiments.

Fine control of the experimental parameters

Two tumblewheel selectors are used to preset the experimental parameters :

1. Filtration times can be adjusted from 10 milliseconds to 10 seconds with an accuracy and reproducibility of a few milliseconds. Longer filtration times may be obtained by using a manual sequence.
2. Buffer flow rate can be preset from 10 µl/s to 10 ml/s.

A digital display allows the operator to monitor the volume of filtration buffer used in each experiment with an accuracy of 1 µl.

Use of standard filters

The Bio-Logic Rapid-Filtration-System uses standard (Diameter = 25 mm) filters of any composition or porosity. On special order the apparatus may be adapted to use other filter dimensions.

Principle of operation

The mechanical subsystem of the Rapid-Filtration-System consists of a movable filter holder (1) and a motorized injection syringe (2)

The sample to be assayed is first layered on the filter with a special adapter (3), the filter holder is then positioned 3 mm under the injection syringe.
The sequence which follows is controlled by the electronic subsystem and its built-in microprocessor.
A strong solenoid is activated which apply the filter holder during a preset time against the lower porous end of the injection syringe.
During that time, the filtration buffer is forced to flow at a preset rate through the filter by the injection syringe, filtered buffer is evacuated from the bottom of the filter holder by a vacuum pump.
The content of the filter is evaluated as in standard filtration experiments.

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Example of application

Specifications

• Syringe volume : 25 ml.
• Material : medical grade stainless steel
• Filtration time : selectable from 10 milliseconds to 10 seconds on automatic mode.
• Buffer flow rate : selectable from 10 µl/s to 10 ml/s.
• Dead time : minimum 10 ms at maximal flow rate.
• Manual or automatic function selector.
• Digital readout of filtration time, flow rate and volume.
• Power requirement: 110-230 V, 50-60Hz
• Weight : 12 kg.

Ordering information

Facility requirement : standard vacuum pump.

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