Zink (1) described a new method for handling solution samples in spectrochemical analysis. This method was based upon a suggestion by Eichhoff (2) in which he proposed the use of a "capillary" electrode to bring the solution to the analytical gap. The method was modified by changing some of the design features of the capillary electrode and adding a Teflon cup. Attempts to obtain spectra of various oil samples by this method failed; this appeared to be due to the size of the axial canal, and the eventual flaming of the oil sample which seriously disrupted the excitation process.
Raymond J. McGowan, "Spectrochemical Analysis of Oils Using "Vacuum Cup" Electrode," Appl. Spectrosc. 15, 179-180 (1961)