Long pathlength absorbance spectroscopy: trace copper analysis using a 4.4 m liquid core waveguide

Procedures are described for measurement of dissolved copper with long pathlength Teflon AF-2400 liquid core waveguides. Using a 4.4 m waveguide, absorbance versus concentration is linear for copper concentrations between 1 and 160 nM. The molar absorbance of copper complexed with bathocuproine disulfonate is nearly identical for pathlengths between 1 cm and 4.4 m. Our 4.4 m waveguide system provided a 0.4 nM detection limit with no sample preconcentration. The methods developed in this study have been used to determine copper concentrations in natural seawater, river water, and commercial drinking water.