A microfluidic chip formed with multiple fluid channels terminating at a
common electrospray ionization tip for mass spectrometric analysis. The
fluid channels may be formed within a substrate plate that are in fluid
communication with corresponding reservoirs. The electrospray tip can be
formed along a defined portion of the substrate plate, wherein the
electrospray tip includes an open-tip region at which the fluid channels
converge. A top laminate plate may substantially enclose most portions of
the fluid channels formed in the bottom polymer plate except for the
open-tip region. Another aspect of the invention provides methods for
conducting mass spectrometric analysis of multiple samples flowing through
individual fluid channels in a single microfluidic chip that is formed
with a convergent electrospray tip. The convergent electrospray tip
includes an open or exposed distal pointed tip region.
