Capillary electrophoresis technique

A sample injector comprising:

• a vacuum source;
• a source of samples;
• a vacuum chamber adapted to receive a vacuum from the vacuum source;
• a liquid-filled capillary tube separating means having first and second ends;
• said vacuum chamber communicating with said liquid-filled capillary tube separating means;
• means for causing said vacuum chamber to communicate with the first end of the liquid-filled capillary tube separating means wherein sample is pulled at a slow rate into the second end of the liquid-filled capillary tube separating means for separating;
• pressure measuring means adapted to measure the pressure in said vacuum chamber and generate a signal indicative thereof;
• said pressure measuring means being adapted to control the transfer of sample;
• said pressure measuring means including an integrator for integrating a signal representing the pressure in the vacuum chamber wherein the amount of sample introduced into said second end of the separation means may be determined.

A method of controlling the amount of sample introduced into a separating means by means of a vacuum controlled sample injector comprising the steps of:

• creating vacuum pressure in a vacuum chamber in contact with a first end of the separating means;
• aspirating sample into a second end of the separating means;
• generating a signal representative of the vacuum pressure in said vacuum chamber;
• integrating the vacuum pressure in said vacuum chamber wherein an indication is provided of the amount of sample introduced;
• and
• using said indication to control the amount of sample.