We report a procedure for the online monitoring of aluminium in drinking water by flow injection analysis. The reaction used is the formation of a complex with morin. Under the working conditions, this can be accomplished in an ethanol-rich hydroalcoholic medium, which modifies the fluorescent characteristics of the complex, allowing the determination of aluminium concentrations higher than 3.1 microgl(-1), with a linear application range between 2 and 250 microgl(-1), an R.S.D. of 2.3% (n=10, 120 microgl(-1)) and a sampling frequency of 90 h(-1). The method can thus be considered one of the most sensitive and fastest for the continuous determination of aluminium. In the presence of anionic surfactants, the sensitivity of the determination is increased. In this form, aluminium is detected at concentrations higher than 2.8 microgl(-1), with a linear application range of 2-50 microgl(-1). The procedure was applied to the analysis of aluminium in drinking, river, and underground water. Under the proposed working conditions, only Fe(III), fluoride and phosphates interfere. The interference of Fe(III) can be avoided with hydroxylamine and that of phosphates and polyphosphates by acid digestion of the samples.

The use of ozonation for the purification of drinking water can lead to the formation of bromate. The US Environmental Protection Agency and the European Directive for human drinking water has lowered the regulatory level for bromate down to 10 microg l(-1), such that methods must be developed for monitoring the formation of bromate, particularly in on-site situations. In the present work we report a fluorometric method for the determination of bromate based on the reaction with carbostyril-124, a compound that shows fluorescence mainly at pH values above 4 and, when bromated, generates a non-fluorescent product. The reaction can thus be used as an indirect method for determination of the ion. The proposed method, which uses the flow injection (FI) technique, allows online application and kinetic control of the variables affecting the process, together with shorter reaction times, and it provides maximum sensitivity and selectivity. Under optimum conditions, it is possible to determine the analyte within the 4-200 microg l(-1) range, with a limit of detection of 0.9 microg l(-1) and a relative standard deviation (n=12, [BrO3-]=5 and 30 microg l(-1)) of 3.2% and 2.6% respectively. The determination rate was ten samples per hour.

This paper report a straightforward approach for the synthesis of CdSe quantum dots (CdSe QDs) in aqueous solution. This method, performed in homogeneous phase, affords optimal sizes and high quantum yields for each application desired. It is ana la carteprocedure for the synthesis of nanoparticles aimed at their later application. By controlling the experimental conditions, CdSe QDs of sizes ranging between 2 and 6 nm can be obtained. The best results were achieved in an ice-bath thermostated at 4°C, using mercaptoacetic acid as dispersant. Under these conditions, a slow growth of quantum nanocrystals was generated and this was controlled kinetically by the hydrolysis ofSeSO32-to generateSe2-  in situ, one of the forming species of the nanocrystal. The organic dispersant mercaptoacetate covalently binds to the Cd2+ion, modifying the diffusion rate of the cation, and plays a key role in the stabilization of CdSe QDs. In optimum conditions, when kept in their own solution CdSe QDs remain dispersed over 4 months. The NPs obtained under optimal conditions show high fluorescence, which is a great advantage as regards their applications. The quantum efficiency is also high, owing to the formation under certain conditions of ananoshellof Cd(OH)2, values of 60% being reached.

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A novel flow injection-gas-diffusion (GD-FI) system has been developed for the on-line analysis of ammonium ion in waters with fluorimetric detection, using an acceptor solution containing the Eosin-Bluish (EB) acid-base indicator. This, together with optimization of the process of gas transfer through the membrane, increases the sensitivity of the method to a considerable extent. Under optimum conditions, it is possible to determine the analyte within the 0.02-1.5 mg l(-1) range, with a limit of detection of 5 microg l(-1) and relative standard deviations (n = 12, [NH (4) (+) ] = 50 microg l(-1) and 0.05 microg l(-1)) of 3.4% and 3.0% respectively. The determination rate was 15 samples per hour.