Flow injection chemiluminescence determination of femtogram-level cobalt in egg yolk, fish tissue and human serum

Femtogram-level cobalt was determined based on its significantly catalyzed effect on luminol-dissolved oxygen chemiluminescence (CL) reaction in the flow system. The increment of CL signal was proportional to the concentration of cobalt, giving linear range from 10 fg ml−1 to 50 pg ml−1 (r2 = 0.9992) with a detection limit 4 fg ml−1 (3σ). At a flow rate of 2.0 ml min−1, a typical analytical procedure for cobalt, including sampling and washing, could be performed in 0.5 min with a relative standard deviation of less than 3.0%. The proposed method has been successfully applied for the determination of cobalt in egg yolk, fish tissue and human serum, agreed well with radioimmunoassay.