Ultrasensitive determination of cobalt and nickel by atomic fluorescence spectrometry using APDC enhanced chemical vapor generation

Abstract

Ammonium pyrrolidine dithiocarbamate (APDC) was used to enhance the chemical vapor generation (CVG) efficiency of nickel and cobalt. Volatile nickel and cobalt species were effectively generated through reduction of acidified analyte solution with 2% potassium tetrahydroborate (KBH4) solution in the presence of 0.02% (m/v) APDC. Thus, a new CVG-atomic fluorescence spectrometric (AFS) method was developed for determination of ultratrace nickel and cobalt. Influencing parameters were evaluated in detail, including the complexing reagents, the concentrations of APDC, nitric acid and KBH4, flow rates of carrier gas and shield gas, lengths of the reaction tube and the transfer tube, as well as interferences. Under the optimized conditions, the limits of detection (LOD) were 1ngmL−1 and 6ngmL−1 for nickel and cobalt, respectively. The calibration curves were linear in the range of 10 to 300ngmL−1 and 50 to 1200ngmL−1 for nickel and cobalt, respectively. The potential application of this method was validated by the accurate determination of nickel in three certified reference materials. It was also applied to determination of cobalt in water samples and Vitamin B12 with good recoveries of spiked samples.