New interface for coupling flow-injection and capillary electrophoresis

A new interface for coupling flow injection analysis (FIA) and capillary electrophoresis (CE) has been developed. An FIA system is connected to a flow-through channel of the interface. One end of a capillary is positioned in a flow-through channel inside the interface together with a platinum electrode. The other end and a second platinum electrode are immersed in a liquid reservoir situated outside the interface. A constant high voltage is applied across the capillary. A sample plug injected in the FIA part of the system is carried by an electrolyte stream towards the interface and when it passes by the first capillary end, a minor fraction of the sample is introduced into the capillary and gets separated. A UV spectrophotometric detector is placed close to the second capillary end. The FIA-CE interface enables multiple injections so that a high sampling throughput can be achieved (up to 150 samples per hour). The interface was tested by running a standard mixture of nine common anions. The repeatability was approximately 2% (r.s.d.). Rapid, qualitative screening of samples can be performed. Real samples such as tap and rain water were also analyzed. The new interface allows mechanized sample handling prior to the CE separation step.