2. Experimental
2.1. Instrumentation
A Perkin-Elmer Model 4100 atomic absorption spectrometer was used in the flame FI mode with a Perkin-Elmer Model AS 91 autosampler. A copper hollow cathode lamp, operated at 15 mA, was used at a wavelength of 324.8 nm with a spectral band-pass of 0.7 nm. Acetylene and air flow-rates were 2.5 and 8.0 l min−1, respectively. The free uptake rate of the nebulizer was adjusted to 6.0 ml min−1. Peak profiles and other statistical data, such as peak area, peak height and precision were displayed on the monitor
screen, and were printed on an Epson LQ-870 printer. Peak area values were used for quantitation and for evaluating dilution factors. The read time (integration time) for peak area evaluation was 20 s with a time constant of 0.7 s.