摘要
Ultratrace amounts of cobalt at parts-per-trilllon (ppt) levels were extracted Into m-xylene from aqueous solution as nitrosonaphthol chelates, and colorimetric determination of the m-xylene phase was carried out with photoacoustic spectroscopy (PAS). Coexistent metals and excessive reagents were completely eliminated by acidic and alkaline washings of the m-xylene phase, and the background level became constant and low enough for ultrasensitive PAS determination. Concentrations of foreign heavy metals, such as Iron, nickel, chromium, and copper, 10 times more than cobalt caused no Interference. The determination limit was obtained as 0.64 ppt based on twice the standard deviation. The reagent 2-nitroso-1-naphthol was more suitable than 1-nltroso-2-naphthol from the viewpoint of stability. © 1986, American Chemical Society. All rights reserved.