Liquid junction apparatus for electrospray ionization

The invention relates to a liquid junction apparatus for electrospray ionization in a mass spectrometer comprising an electrospray emitter, a capillary conduit assembly for conducting liquid to be electrosprayed, and a union comprising an electrically conductive material, in which the electrospray emitter and the capillary conduit assembly are accommodated in a bottom-sealing butt joint featuring low dead volume while retaining at least one of them pluggable and withdrawable. The liquid junction apparatus facilitates energizing the transmitted liquid to a predetermined voltage level at the liquid junction upstream of an actual emitter tip where electrospraying occurs, while retaining at least one of an electrospray emitter and a capillary conduit assembly pluggable into and withdrawable from a union that comprises a conductive material.