CS244869B1 - Method of static wetting of capillaries with a stationary phase solution - Google Patents

Abstract

The essence of the method is that the capillary is filled with a solution of the stationary phase in a low-boiling solvent and the whole is maintained at a temperature higher than the boiling point of the solution.

Description

The invention relates to a method of static wetting of capillaries with a stationary phase solution without using vacuum.

One crucial step in the preparation of high performance capillary columns for gas or liquid chromatography is to apply a thin homogeneous film of the stationary phase to the inner surface of the capillary, i.e. wetting the capillary with a stationary phase solution.

Three methods of wetting are known. Dynamic, pressure static according to Iik and Mistrjukov and classical static according to Bouch and Verzel. All are used, the most reproducible results are classic static wetting.

In this method, the capillary is filled with a solution of the stationary phase in a volatile solvent and one end of the capillary is sealed in a gas-tight manner so that even the smallest gas bubble is not left inside the capillary.

A vacuum is applied to the open end and a stationary phase film is drawn on the capillary wall by sucking off the solvent vapors. The advantage of this method is the high reproducibility and knowledge of the amount of stationary phase that is applied to the column wall.

Disadvantages include the already mentioned need for a gas-tight closure without the smallest gas bubble. Furthermore, this method is time-consuming. The wetting of the 1 m capillary using dichloromethane as solvent takes about 1 hour.

In addition, it is necessary to thermostat the solution capillary and maintain an approximately constant vacuum value throughout the wetting. These disadvantages are eliminated by the method of static wetting of capillaries with a stationary phase solution, which is based on the fact that the capillary is filled with a stationary phase solution in a low boiling solvent and is kept at a temperature above the boiling point of the solvent.

The method according to the invention makes it possible to accelerate the entire process of wetting the capillaries and to simplify the necessary equipment.

BRIEF DESCRIPTION OF THE DRAWINGS The invention illustrates an exemplary embodiment of the accompanying drawing, in which the apparatus required for filling and wetting capillaries with liquefied propane-butane is illustrated.

In the drawing, a reservoir 6 with a solution 6 of the stationary phase into which the end of the capillary 6 is mounted is shown. The gasket is provided by the sealing disc 4 and the union nut 4.

At the other end of the capillary tube 6, a needle valve 6 is mounted and the overflowing solution is collected in the container 6.

The process is carried out as follows. The required amount of stationary phase is weighed into the reservoir and the reservoir is closed by the sealing disc 3 and the union nut. The required amount of propane-butane is injected into the reservoir 6 by piercing the sealing disc 6 and the resulting solution is shaken.

The free end of the capillary 5 is then inserted into solution 2. The connected needle valve 6 at the other end of the capillary 6 opens and the solution 8 flows into the capillary 6. Excess solution flows through the needle valve 6 into the container 6.

Once the capillary 8 is washed with the solution, the valve 8 is closed and the other end of the capillary is withdrawn from the reservoir 8. The capillary 6 is placed under the beaker and allowed to lie until the entire length of the solution has evaporated. The needle valve 6 is then disconnected and the capillary column is complete.

Claims (1)

A method of static wetting of capillaries with a stationary phase solution, characterized in that the hood is filled with a stationary phase solution in a low boiling solvent and is kept at a temperature higher than the boiling point of the solvent.