2. Experimental
2.1. Apparatus
The GF AAS measurements of the metals were performed with a Varian AA240Z (Mulgrave, Australia) electrothermal atomic absorption spectrometer equipped with a Varian GTA 120 graphite furnace and a Zeeman-effect background corrector. The injection of the samples was performed by a Varian PSD 120 auto sampler and codified hollowcathode lamps for copper, iron and lead were employed in all experiments. Integrated absorbance measurements were performed by using partitioned graphite tubes (coated with pyrolytic graphite), also supplied by Varian (part no. 63-100012-00). Argon (99.99% purity, supplied by Linde Gases, Macaé, Brazil) was used as protective gas. Operational conditions used for the measurements of all elements under study are shown in
Table 1.