A single or multiple layer curved Electrospray sample introduction means has been configured in an Atmospheric Pressure Ion (API) source interfaced to a mass analyzer. Sample solutions introduced through curved or bent sample introduction Electrospray (ES) probes configured in an API source are sprayed from the ES probe tip at an angle which differs from centerline of the ES probe body. Single or multiple curved ES probes can be configured in an Atmospheric Pressure Ion source interfaced to mass analyzers. Curved ES probes can also be configured in an API source which includes Atmospheric Pressure Chemical ionization.