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A new flow injection (FI) system for the determination of Pb(II) at trace level with a preconcentration step and spectrophotometric detection is proposed. It is based on preconcentration of lead ions on chitosan and dithizone-lead complex formation in aqueous medium (pH 9). The chemicals and FIA variables influencing the performance of the system were optimized and applied to the determination of lead in natural, well, and drinking water samples. It is a simple, highly sensitive, and low cost alternative methodology. The method provided a linear rage between 25 and 250mugl(-1), a detection limit of 5.0ngml(-1) and a sample throughput of 15h(-1). The obtained results of spiked samples are in good agreement between the proposed method and ICP-AES.

Patagonia, due to its geographic position and the dominance of westerly winds, is a key area that contributes to the supply of nutrients to the Southern Ocean, both through mineral dust and through the periodic deposits of volcanic ash. Here we evaluate the characteristics of Fe dissolved (into soluble and colloidal species) from volcanic ash for three recent southern Andes volcanic eruptions having contrasting features and chemical compositions. Contact between cloud waters (wet deposition) and end-members of andesitic (Hudson volcano) and rhyolitic (Chaitén volcano) materials was simulated. Results indicate higher Fe release and faster liberation rates in the andesitic material. Fe release during particle-seawater interaction (dry deposition) has higher rates in rhyolitic-type ashes. Rhyolitic ashes under acidic conditions release Fe in higher amounts and at a slower rate, while in those samples containing mostly glass shards, Fe release was lower and faster. The 2011 Puyehue eruption was observed by a dust monitoring station. Puyehue-type eruptions can contribute soluble Fe to the ocean via dry or wet deposition, nearly reaching the limit required for phytoplankton growth. In contrast, the input of Fe after processing by an acidic eruption plume could raise the amount of dissolved Fe in surface ocean waters several times, above the threshold required to initiate phytoplankton blooms. A single eruption like the Puyehue one represents more than half of the yearly Fe flux contributed by dust.

A novel flow injection analysis (FIA) method with Rayleigh light scattering (RLS) detection was developed for the determination of total protein concentrations. This method is based on the weak intensity of RLS of bromothymol blue (BB) (3',3"-dibromothymolsulfonephthalein) which can be enhanced by the addition of protein in weakly acidic solution. A common spectrofluorimeter was used as a detector. It was proved that the application of this method to quantify the total proteins in real samples by using bovine serum albumin was possible. The RLS signal was detected at lambda(ex)= lambda(em)=572 nm. The linear range was 7.0-70.0 microg mL(-1), the detection limit was 3.75 microg mL(-1), the reproducibility was 5.5% (n=7), and the sample throughput was 26 h(-1).

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