Gas-diffusion Preconcentration Systems

Fig. 7a FI manifold of gas-diffusion preconcentration system using multifunctional valve with time-based sampling (valve in injection position). Experimental conditions are for the preconcentration of ammonia. S. sample C, carrier (water) R], reagent for generation of volatile species (base) R2, acceptor reagent stream (buffered acid-base indicator) V.

Hara et al.[34] used an on-line gas-diffusion preconcentration system for the determination of ammonium ions in distilled and natural water samples with an ion-selective electrode detector. The preconcentration was achieved by maintaining a time-based large sample flow of about 10 ml min against a low acceptor buffer flow of only 0.3 ml min" A detection limit of 30-3 fig 1 was reported. 

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