Determination of copper in seawater by using a sequential injection system incorporating a sample pretreatment module coupled to electrothermal atomic absorption spectrometry

An automated sequential injection system incorporating a sample pretreatment module was developed for the separation and preconcentration of ultra-trace copper in seawater without dilution. Cu-pyrrolidine dithiocarbamate (PDC) chelate was retained in a polytetrafluoroethylene ( PTFE) beads packed column in the module, which was afterwards eluted with a small amount of methanol and the eluate was quantified by using electrothermal atomic absorption spectrometry (ETAAS). An enrichment factor of 20, a limit detection of 0.015 mu g/L, along with a sampling frequency of 26/h were obtained with a sampling volume of 1.0 mL within the concentration range of 0.05 - 1.00 mu g/L, achieving a precision of 1.8% RSD at the 0.50 mu g/L level (n=7). The system was validated by analyzing a certified reference material of seawater, NASS-5, and further demonstrated by spiking recoveries in a coastal seawater sample employing various dilution factors.