Abstract: An apparatus for use as an ion source for mass analysis includes a nebulizing device, a vaporizing device, a chamber, an ion sampling structure, and an ionizing device. The vaporizing device includes a vaporizing interior that terminates at a vaporizing device outlet. The chamber fluidly communicates with the vaporizing device outlet. The ion sampling structure has an ion sampling inlet fluidly communicating with the chamber and spaced from the vaporizing device outlet. The ionizing device includes first and second electrodes positioned to produce an electrical discharge therebetween a location closer to the vaporizing device outlet than to the ion sampling inlet.