ABSTRACT
Flow injection on-line sorption preconcentration and separation in a knotted reactor (KR) was coupled to cold vapor atomic fluorescence spectrometry for the determination of trace mercury in mineral water. Mercury was preconcentrated by on-line formation of mercury diethyldithiocarbamate complex (Hg-DDTC) and absorption of the resulting neutral complex on the inner walls of a knotted reactor. A 20%(V/V) HNO3 solution heated by electromagnetic induction heating technique was used as eluent to remove the absorbed Hg-DDTC from the KR, and then the vapor mercury generated by mixing the resulting solution and KBH4 was determined on-line by cold vapor atomic fluorescence spectrometry. The 20% HNO3 was employed as both the efficient eluent and the required acidic medium for subsequent mercury vapor generation in our work. Using 20% HNO3 instead of conventional organic solvent as eluent, the proposed method is simple, easy operational and environmentally friendly. Under the optimal experimental conditions, the sample throughput was approximatively 30/h with an enhancement factor of 35. The detection limit of mercury was 2.0 ng/L. The precision(RSD, n=11) was 2.2% at the 0.1 μg/L Hg2+ level.