Determination of copper species in atmospheric waters

Abstract

The total copper concentration was determined in rainwater and roof runoff collected in Plymouth, UK between Sept-Oct 2013. The concentration was measured using inductively coupled plasma mass spectrometry and found to be 2.19 ± 0.456 and 3.18 ± 0.506 μg L-1 for rainwater and roof runoff, respectively. These were found to coincide with other published rainwater Cu concentrations. The method itself showed poor accuracy, with a 77.6% recovery for Cu. A method for the determination of Cu(I) by ultraviolet-visible spectrophotometry using bathocuproine was also evaluated. A series of Cu(I)Br calibration standards between concentrations of 0.05 and 0.5 mM were used to assess the absorbance of the [Cu(BCP)2]+ complex at a various pH ranges. Ethylenediamine was used to mask inferences caused by Cu(II). The [Cu(BCP)2]+ complex was observed to be most stable as a pH >8.0, resulting in the highest absorbance throughout the pH ranges. Opened and closed systems were used to evaluate the oxidation of Cu(I) in the presence of air. The open system saw a small decrease in absorbance, inferring the oxidation rate of Cu(I) was not rapid, with only a partial Cu(I) oxidation. The limit of detection for Cu(I) using this method was found to be 1.11 x 10-4 M, concluding that the method was unsuitable for quantifying Cu(I) in atmospheric waters.