A straight line passing through the origin was obtained for the
calibration graph at kmax. Beer’s law is obeyed in the concentration
range of 20–450 ng mL1 in the original solution (Table 1), whiles
the optimum concentration range for accurate determination, as
investigated from the Ringbom plot, is 50–430 ng mL1 in the presence
of p-dichlorobenzene. In its absence, Beer’s law is obeyed in
the concentration range of 200–9000 ng mL1 (Table 1), while
the optimum concentration range for accurate determination, as
investigated from the Ringbom plot, is 500–8700 ng mL1.