Hermetically-sealed miniaturized discharge ionization detector

A discharge ionization detector 1 comprises a ceramic detector body 34, a detector cavity 3, a first discharge electrode 8 and a second discharge electrode 40, wherein an electric discharge runs between the two, and a signal electrode 18 which attracts ionised molecules. The detector also comprises an inlet interface 4 through which a carrier gas 2 enters the detector 1, an analyte inlet 19 through which the analyte to be detected enters the detector cavity 3, and an outlet 11 through which the analyte and discharge gas exit the detector body 34. The apparatus is hermetically sealed by vacuum brazing the components to the detector body 34, and by use of a purge gas pathway 7, that prevents air leaks from entering the detector body. The detection volume may be between 5 and 100 micro-litres.