Use of flow injection and sequential injection analysis schemes for the determination of trace-level concentrations of metals in complex matrices by ETAAS and ICPMS

Despite their excellent analytical chemical capacities for determination of low levels of metal species, electrothermal atomic absorption spectrometry and inductively coupled plasma mass spectrometry often require suitable pretreatment (separation and preconcentration) of the sample material to facilitate the desired sensitivity and selectivity of measurement. Such pretreatment schemes are advantageously performed in flow injection (FI) or sequential injection (SI) manifolds, where all unit operations can be effected on-line and under enclosed and strictly controlled conditions. Various separation/preconcentration procedures are feasible, such as liquid-liquid extraction (possibly including back extraction), (co)precipitation with collection in knotted coils, adsorption on hydrophilic or hydrophobic reactors, hydride generation, or the use of ionexchange/chelating packed columns. After describing the particulars and characteristics of FI and SI, we present, via selected examples, various separation/preconcentration FI/Sl schemes for the determination of trace levels of metals, with particular emphasis on the use of the novel extension of FI/SI, that is, the so-called lab-on-valve concept.