Determination of Copper in Seawater 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-PDC (pyrrolidine dithiocarbamate) chelate was retained in a PTFE-beads-packed column in the module, which was later eluted with a small amount of methanol, and the eluate was quantified using electrothermal atomic absorption spectrometry (ETAAS). An enrichment factor of 20, a limit detection of 0.015 μg l−1, and a sampling frequency of 26 per hour were obtained with a sampling volume of 1.0 ml within the concentration range of 0.05–1.00 μg l−1, achieving a precision of 1.8% RSD (n = 7) at the level of 0.50 μg l−1. The system was validated by analyzing a certified reference material of seawater, NASS-5, and was further demonstrated by spiking recoveries in a coastal seawater sample employing various dilution factors.