Filterless Systems with Precipitate Dissolution

A schematic diagram of the simplest version of such systems used with a flame AAS detector is shown in Fig. 7.5 [21]. The system is composed of two independently controlled pumps and a 4 5 channel rotary injection valve, identical to that used for on-line column preconcentration (cf. Fig 4.11). The system has been used successfully for coprecipitation applications with organic precipitants, where relatively large amounts of precipitates were formed using a carrier. 

Recently the system has been adapted with minor modifications to on-line preconcentration by coprecipitation for an ETAAS system (Fig. 7.6) [23]. Owing to the discontinuous nature of the operation in ETAAS, the term on-line is used in the sense that 

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Fig.7 Schematic diagram of a FI filterless on-line precipitation system with precipitate dissolution using a knoned reactor (KR) as precipitate collector, a. sample loading (precipitate collection) sequence b, precipitate dissolution sequence. Pi. P2. peristaltic pumps V. 4 5 channel injector valve PR. precipitant S. sample R. buffer reagent (optional) DS, dissolution solvent KR, knoned reactor precipitate collector and W, waste [21].

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