Determination of nickel, cobalt and manganese in serum by graphite-furnace AAS after treatment at high concentration of ammonia

Trace amounts of nickel, cobalt and manganese in serum were determined by graphite-furnace AAS after a treatment with a high concentration (7.5 M) of ammonia solution. Serum was diluted with ammonia water 2 similar to 4 times because the content of these elements in serum was very low and close to the detection limit. This diluted solution was injected with hydrogen peroxide into a graphite furnace. A surfactant was unnecessary because the viscosity of the sample solution was reduced by the treatment with ammonia water. The temperature of the graphite furnace used to make the sample oxidize and to dry it was kept at 80 similar to 110 degrees C for 180 s. As a results, the Charateristic Mass (pg/0.0044 Abs) became smaller than that of the recommended method. Ni, Co and Mn concentrations in seronorm (TM) reference human serum were estimated to be 5.49, 1.09 and 10.1 mu g/1 with % RSD values of 1.1, 1.6 and 5.3, respectively. These values agreed well with the certified values of Ni, Co and Mn.