The first work I did on spark discharges was using the "Spark-in-Spray, a device envisioned by Howard Malmstadt at the University of Illinois, and developed in working detail in the Ph.D. thesis of Al Schalge between 1956 and 1959. A picture is shown below:
In this device, a Beckman® total consumption burner is modified so that the outer flame jacket is removed and the inner nebulizer is used to spray a liquid into the spark gap formed between two carbon electrodes. An oscillatory, high-voltage spark source is used to pass a discharge between the two electrodes about every two milliseconds, while the nebulizer is spraying. The result is as shown above, and in magnified form below.
When I used built the above device in 1961, and used it on a Bausch and Lomb® large Littrow quartz spectrograph with photographic plate detection, excellent spectra were obtained with detection limits typically running to one part-per-million or so for almost all of the transition metals.
I became fascinated with the chemistry of standard solution preparation, the electrical aspects of the spark discharge, the spectrographic process, and the whole business of trying to understand the line-to-background ratios. This, of course, all preceded the commercialization of the ICP. But, it was one aspect of spark discharges that kept me in business doing spectrochemical research until 1982, when I left the federally-controlled game of large university research funding for a more civilized career in undergraduate teaching at St. Olaf College. But, even though I am now retired, I am still fascinated by this device. With better detectors and simpler, electronic spark sources and positionally-stabilized sparks, who knows where this could go if re-developed today. It was way ahead of its time back then.