The FAAS analytical signal increased proportionally with
increasing pre-concentration time, which means that retention
efficiency was constant. The experimental pre-concentration
factor, calculated as the ratio of the slopes of the calibration
graphs obtained with and without pre-concentration, was
evaluated as 15.7. Sample volumes greater than 3.4 ml can be
used and thus higher pre-concentration factors can be achieved;
for a sample volume of 10 ml, a pre-concentration factor of 47
was achieved. As the sample volume used in the method was 3.4
ml and the injected eluent volume was 213 ml, the theoretical
pre-concentration factor should be 16, which demonstrates the
good performance and the minimum dispersion of the FI
system.