Abstract
Flow-injection manifolds are described which allow the preconcentration
of lead for flame atomic absorption determinations, using
columns contained within the sample loop of an injection valve. An
interface was designed which allowed the valves and pump in the
system to be controlled by an autosampler which enabled precise
timing of preconcentration and elution steps. The effects of sample
flow rate, buffer pH and buffer type for preconcentration and
eluent concentration and flow rate were investigated in order to
obtain optimum performance of the system. A 50-times improvement
in detection limits over conventional sample introduction was
obtained for a sample volume of approximately 12 ml, preconcentrated for
150 s. The injection of eluent, as opposed to the use of a
continuously flowing eluent stream, enabled this reagent to be
conserved.