“…Barker and Jenkins (I), who first reported the use of a square-wave polarograph, predicted a sensitivity to reducible species as low as 2 X 10-8M. Since then Ferrett, Milner, and Smales have used this technique to analyze for less than 1 ppm lead in cocoa (2), Niki, Sirai, and Kyoya have measured 2 X 10~7M lead and cadmium in phosphoric acid (3), Goode and Campbell (4) have analyzed uranium metal for less than 5 ppm each of copper, lead, cadmium, and zinc and Kashiki and Oshima determined 0.01 ppm free sulfur in petroleum (5). Square-wave polarography in combination with anodic (5) M. Kashiki and S. Oshima, Bull.…”