Metastable ionisation and emission detector, and related methods

A system for chromatographically analyzing a sample, the system comprising:

• a metastable species source, the metastable species source comprising:
• a plasma chamber having an inlet and an outlet, the inlet being configured to receive a gas stream;
• a plasma discharge mechanism configured to produce a plasma from the gas stream circulating in the plasma chamber, the plasma comprising at least metastable species and electrically-charged species;
• and
• a conduit in fluid communication with the outlet of the plasma chamber and adapted to receive the gas from the plasma chamber, the conduit comprising an electrically-conductive region configured to trap the electrically-charged species and allow circulation of the metastable species;
• a measurement chamber configured to:
• receive the sample from a chromatography method, the sample comprising an analyte and a non-analyte;
• and
• receive the metastable species after circulation of the gas from the plasma chamber in the conduit, wherein an interaction between the metastable species and the sample produces an excited or ionized analyte, without exciting or ionizing the non-analyte;
• and
• a detector configured to obtain a sample chromatogram from the excited or ionized analyte.