Determination of Trace Amounts of Mercury, Lead, and Cadmium in Steel and Iron Orel

Trace amounts of mercury in steel and iron ore were determined by direct vaporization from solid sample and reduction vaporization from digested sample solution with cold-vapor atomic absorption spectrometry. The direct method has been applied to the determination of mercury in iron ore in the level of ng/g with satisfactory precision equal to the reduction method. However, mercury in steel could not be detected by the both methods. Trace amounts of mercury in steel, lead, and cadmium in the level of ng/g in steel have been determined by inductively coupled plasma-mass spectrometry (ICP-MS) after cation exchange chromatographic separation. The sample was decomposed with nitric acid and separated from iron matrix in 1 M hydrofluoric acid solution, using the cation exchange resin that were packed in a mini-column. The elements adsorbed on the resin were eluted by 6 M hydrochloric acid solution and determined by ICP-MS simultaneously. The lower limits of detection based on 3a of blank values were 2 ng/g for mercury, 9 ng/g for lead, and 0.5 ng/g for cadmium in steel.