Miniature ion source of fixed geometry

A mass spectrometer comprising:

• an atmospheric pressure interface comprising a gas cone having an inlet aperture, wherein said gas cone has a first longitudinal axis arranged along an x-axis;
• an Electrospray ion source comprising a first capillary tube having an outlet and having a second longitudinal axis and a second capillary tube which surrounds said first capillary tube;
• a desolvation gas supply tube;
• an analyte liquid supply arranged and adapted to supply an analyte liquid via said first capillary tube so that said liquid exits said outlet of said first capillary tube;
• and
• a nebuliser gas supply arranged and adapted to supply a nebuliser gas via said second capillary tube;
• wherein an outlet of said first capillary tube is arranged at a distance x mm along said x-axis as measured from the centre of said gas cone inlet aperture, a distance y mm along a y-axis as measured from the centre of said gas cone inlet aperture and a distance z mm along a z-axis as measured from the centre of said gas cone inlet aperture;
• wherein said x-axis, said y-axis and said z-axis are mutually orthogonal;
• wherein:
• said desolvation gas supply tube surrounds said second capillary tube;
• and wherein said mass spectrometer further comprises:
• a desolvation gas supply arranged and adapted to supply a desolvation gas via said desolvation gas supply tube;
• a heater arranged and adapted to heat said desolvation gas;
• and
• a cone gas supply arranged and adapted to supply a cone gas to said gas cone.

A method of mass spectrometry comprising:

• providing an atmospheric pressure interface comprising a gas cone having an inlet aperture, wherein said gas cone has a first longitudinal axis arranged along an x-axis;
• providing an Electrospray ion source comprising a first capillary tube having an outlet and having a second longitudinal axis and a second capillary tube which surrounds said first capillary tube;
• supplying an analyte liquid via said first capillary tube so that said liquid exits said outlet of said first capillary tube;
• and
• supplying a nebuliser gas via said second capillary tube;
• wherein an outlet of said first capillary tube is arranged at a distance x mm along said x-axis as measured from the centre of said gas cone inlet aperture, a distance y mm along a y-axis as measured from the centre of said gas cone inlet aperture and a distance z mm along a z-axis as measured from the centre of said gas cone inlet aperture;
• and
• wherein said x-axis, said y-axis and said z-axis are mutually orthogonal;
• wherein said method further comprises:
• providing a desolvation gas supply tube which surrounds said second capillary tube;
• supplying a desolvation gas via said desolvation gas supply tube;
• heating said desolvation gas;
• and
• supplying a cone gas to said gas cone.