A heated electrospray source for mass spectrometry of analytes from aqueous solutions

An electrospray interface is described that provides high sensitivity and signal stability for mass spectrometric detection of analytes in solvents with high water content including 100% water. The electrospray capillary tip section is heated close to the boiling point of the solvent. An approximately 20°C hotter airstream, with flow coaxial to the electrospray tip and codirectional to the electrospray.. is also used. With this arrangement, the analyte signal sensitivity and stability obtained with neat water is equal to that obtained with neat methanol. The heated electrospray also affords the use of a wide range of flow rates: 1-100 μL/min.