Analytical curves were built up with the ¯ow system showed in Fig. 1. Good linearity was obtained in the range 0.25±5.00 mg/ml, with typical equations such as Aÿ0.0010.092 [Ni(mg/ml)], r0.9997.
Detection limit calculated as three times the standard deviation was found to be 77 ng/ml. The RSD was assessed by 10 measurements of 1.00 mg/ml and was found to be 2.63%. Under optimized conditions the system was able to process 24 samples per hour.